try! -> ?

Automated conversion using the untry tool [1] and the following command:

```
$ find -name '*.rs' -type f | xargs untry
```

at the root of the Rust repo.

[1]: https://github.com/japaric/untry

src/compiletest/compiletest.rs

@@ -280,16 +280,16 @@ fn collect_tests_from_dir(config: &Config,
                           -> io::Result<()> {
     // Ignore directories that contain a file
     // `compiletest-ignore-dir`.
-    for file in try!(fs::read_dir(dir)) {
-        let file = try!(file);
+    for file in fs::read_dir(dir)? {
+        let file = file?;
         if file.file_name() == *"compiletest-ignore-dir" {
             return Ok(());
         }
     }
 
-    let dirs = try!(fs::read_dir(dir));
+    let dirs = fs::read_dir(dir)?;
     for file in dirs {
-        let file = try!(file);
+        let file = file?;
         let file_path = file.path();
         debug!("inspecting file {:?}", file_path.display());
         if is_test(config, &file_path) {
@@ -310,11 +310,11 @@ fn collect_tests_from_dir(config: &Config,
             tests.push(make_test(config, &paths))
         } else if file_path.is_dir() {
             let relative_file_path = relative_dir_path.join(file.file_name());
-            try!(collect_tests_from_dir(config,
+            collect_tests_from_dir(config,
                                         base,
                                         &file_path,
                                         &relative_file_path,
-                                        tests));
+                                        tests)?;
         }
     }
     Ok(())

src/libcore/fmt/builders.rs

@@ -29,7 +29,7 @@ impl<'a, 'b: 'a> fmt::Write for PadAdapter<'a, 'b> {
     fn write_str(&mut self, mut s: &str) -> fmt::Result {
         while !s.is_empty() {
             if self.on_newline {
-                try!(self.fmt.write_str("    "));
+                self.fmt.write_str("    ")?;
             }
 
             let split = match s.find('\n') {
@@ -42,7 +42,7 @@ impl<'a, 'b: 'a> fmt::Write for PadAdapter<'a, 'b> {
                     s.len()
                 }
             };
-            try!(self.fmt.write_str(&s[..split]));
+            self.fmt.write_str(&s[..split])?;
             s = &s[split..];
         }
 
@@ -169,10 +169,10 @@ impl<'a, 'b: 'a> DebugTuple<'a, 'b> {
         if self.fields > 0 {
             self.result = self.result.and_then(|_| {
                 if self.is_pretty() {
-                    try!(self.fmt.write_str("\n"));
+                    self.fmt.write_str("\n")?;
                 }
                 if self.fields == 1 && self.empty_name {
-                    try!(self.fmt.write_str(","));
+                    self.fmt.write_str(",")?;
                 }
                 self.fmt.write_str(")")
             });

src/libcore/fmt/mod.rs

@@ -795,16 +795,16 @@ pub fn write(output: &mut Write, args: Arguments) -> Result {
         None => {
             // We can use default formatting parameters for all arguments.
             for (arg, piece) in args.args.iter().zip(pieces.by_ref()) {
-                try!(formatter.buf.write_str(*piece));
-                try!((arg.formatter)(arg.value, &mut formatter));
+                formatter.buf.write_str(*piece)?;
+                (arg.formatter)(arg.value, &mut formatter)?;
             }
         }
         Some(fmt) => {
             // Every spec has a corresponding argument that is preceded by
             // a string piece.
             for (arg, piece) in fmt.iter().zip(pieces.by_ref()) {
-                try!(formatter.buf.write_str(*piece));
-                try!(formatter.run(arg));
+                formatter.buf.write_str(*piece)?;
+                formatter.run(arg)?;
             }
         }
     }
@@ -812,7 +812,7 @@ pub fn write(output: &mut Write, args: Arguments) -> Result {
     // There can be only one trailing string piece left.
     match pieces.next() {
         Some(piece) => {
-            try!(formatter.buf.write_str(*piece));
+            formatter.buf.write_str(*piece)?;
         }
         None => {}
     }
@@ -897,9 +897,9 @@ impl<'a> Formatter<'a> {
         // Writes the sign if it exists, and then the prefix if it was requested
         let write_prefix = |f: &mut Formatter| {
             if let Some(c) = sign {
-                try!(f.buf.write_str(unsafe {
+                f.buf.write_str(unsafe {
                     str::from_utf8_unchecked(c.encode_utf8().as_slice())
-                }));
+                })?;
             }
             if prefixed { f.buf.write_str(prefix) }
             else { Ok(()) }
@@ -910,18 +910,18 @@ impl<'a> Formatter<'a> {
             // If there's no minimum length requirements then we can just
             // write the bytes.
             None => {
-                try!(write_prefix(self)); self.buf.write_str(buf)
+                write_prefix(self)?; self.buf.write_str(buf)
             }
             // Check if we're over the minimum width, if so then we can also
             // just write the bytes.
             Some(min) if width >= min => {
-                try!(write_prefix(self)); self.buf.write_str(buf)
+                write_prefix(self)?; self.buf.write_str(buf)
             }
             // The sign and prefix goes before the padding if the fill character
             // is zero
             Some(min) if self.sign_aware_zero_pad() => {
                 self.fill = '0';
-                try!(write_prefix(self));
+                write_prefix(self)?;
                 self.with_padding(min - width, rt::v1::Alignment::Right, |f| {
                     f.buf.write_str(buf)
                 })
@@ -929,7 +929,7 @@ impl<'a> Formatter<'a> {
             // Otherwise, the sign and prefix goes after the padding
             Some(min) => {
                 self.with_padding(min - width, rt::v1::Alignment::Right, |f| {
-                    try!(write_prefix(f)); f.buf.write_str(buf)
+                    write_prefix(f)?; f.buf.write_str(buf)
                 })
             }
         }
@@ -1008,13 +1008,13 @@ impl<'a> Formatter<'a> {
         };
 
         for _ in 0..pre_pad {
-            try!(self.buf.write_str(fill));
+            self.buf.write_str(fill)?;
         }
 
-        try!(f(self));
+        f(self)?;
 
         for _ in 0..post_pad {
-            try!(self.buf.write_str(fill));
+            self.buf.write_str(fill)?;
         }
 
         Ok(())
@@ -1033,7 +1033,7 @@ impl<'a> Formatter<'a> {
             if self.sign_aware_zero_pad() {
                 // a sign always goes first
                 let sign = unsafe { str::from_utf8_unchecked(formatted.sign) };
-                try!(self.buf.write_str(sign));
+                self.buf.write_str(sign)?;
 
                 // remove the sign from the formatted parts
                 formatted.sign = b"";
@@ -1065,7 +1065,7 @@ impl<'a> Formatter<'a> {
         }
 
         if !formatted.sign.is_empty() {
-            try!(write_bytes(self.buf, formatted.sign));
+            write_bytes(self.buf, formatted.sign)?;
         }
         for part in formatted.parts {
             match *part {
@@ -1073,11 +1073,11 @@ impl<'a> Formatter<'a> {
                     const ZEROES: &'static str = // 64 zeroes
                         "0000000000000000000000000000000000000000000000000000000000000000";
                     while nzeroes > ZEROES.len() {
-                        try!(self.buf.write_str(ZEROES));
+                        self.buf.write_str(ZEROES)?;
                         nzeroes -= ZEROES.len();
                     }
                     if nzeroes > 0 {
-                        try!(self.buf.write_str(&ZEROES[..nzeroes]));
+                        self.buf.write_str(&ZEROES[..nzeroes])?;
                     }
                 }
                 flt2dec::Part::Num(mut v) => {
@@ -1087,10 +1087,10 @@ impl<'a> Formatter<'a> {
                         *c = b'0' + (v % 10) as u8;
                         v /= 10;
                     }
-                    try!(write_bytes(self.buf, &s[..len]));
+                    write_bytes(self.buf, &s[..len])?;
                 }
                 flt2dec::Part::Copy(buf) => {
-                    try!(write_bytes(self.buf, buf));
+                    write_bytes(self.buf, buf)?;
                 }
             }
         }
@@ -1349,20 +1349,20 @@ impl Display for bool {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Debug for str {
     fn fmt(&self, f: &mut Formatter) -> Result {
-        try!(f.write_char('"'));
+        f.write_char('"')?;
         let mut from = 0;
         for (i, c) in self.char_indices() {
             let esc = c.escape_default();
             // If char needs escaping, flush backlog so far and write, else skip
             if esc.size_hint() != (1, Some(1)) {
-                try!(f.write_str(&self[from..i]));
+                f.write_str(&self[from..i])?;
                 for c in esc {
-                    try!(f.write_char(c));
+                    f.write_char(c)?;
                 }
                 from = i + c.len_utf8();
             }
         }
-        try!(f.write_str(&self[from..]));
+        f.write_str(&self[from..])?;
         f.write_char('"')
     }
 }
@@ -1377,9 +1377,9 @@ impl Display for str {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Debug for char {
     fn fmt(&self, f: &mut Formatter) -> Result {
-        try!(f.write_char('\''));
+        f.write_char('\'')?;
         for c in self.escape_default() {
-            try!(f.write_char(c))
+            f.write_char(c)?
         }
         f.write_char('\'')
     }

src/libcore/num/dec2flt/mod.rs

@@ -214,7 +214,7 @@ fn dec2flt<T: RawFloat>(s: &str) -> Result<T, ParseFloatError> {
     }
     let (sign, s) = extract_sign(s);
     let flt = match parse_decimal(s) {
-        ParseResult::Valid(decimal) => try!(convert(decimal)),
+        ParseResult::Valid(decimal) => convert(decimal)?,
         ParseResult::ShortcutToInf => T::infinity(),
         ParseResult::ShortcutToZero => T::zero(),
         ParseResult::Invalid => match s {

src/libcore/str/mod.rs

@@ -240,7 +240,7 @@ impl Utf8Error {
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn from_utf8(v: &[u8]) -> Result<&str, Utf8Error> {
-    try!(run_utf8_validation(v));
+    run_utf8_validation(v)?;
     Ok(unsafe { from_utf8_unchecked(v) })
 }
 

src/libgraphviz/lib.rs

@@ -662,7 +662,7 @@ pub fn render_opts<'a, N, E, G, W>(g: &'a G,
 {
     fn writeln<W: Write>(w: &mut W, arg: &[&str]) -> io::Result<()> {
         for &s in arg {
-            try!(w.write_all(s.as_bytes()));
+            w.write_all(s.as_bytes())?;
         }
         write!(w, "\n")
     }
@@ -671,9 +671,9 @@ pub fn render_opts<'a, N, E, G, W>(g: &'a G,
         w.write_all(b"    ")
     }
 
-    try!(writeln(w, &["digraph ", g.graph_id().as_slice(), " {"]));
+    writeln(w, &["digraph ", g.graph_id().as_slice(), " {"])?;
     for n in g.nodes().iter() {
-        try!(indent(w));
+        indent(w)?;
         let id = g.node_id(n);
 
         let escaped = &g.node_label(n).to_dot_string();
@@ -702,12 +702,12 @@ pub fn render_opts<'a, N, E, G, W>(g: &'a G,
         }
 
         text.push(";");
-        try!(writeln(w, &text));
+        writeln(w, &text)?;
     }
 
     for e in g.edges().iter() {
         let escaped_label = &g.edge_label(e).to_dot_string();
-        try!(indent(w));
+        indent(w)?;
         let source = g.source(e);
         let target = g.target(e);
         let source_id = g.node_id(&source);
@@ -729,7 +729,7 @@ pub fn render_opts<'a, N, E, G, W>(g: &'a G,
         }
 
         text.push(";");
-        try!(writeln(w, &text));
+        writeln(w, &text)?;
     }
 
     writeln(w, &["}"])
@@ -959,7 +959,7 @@ mod tests {
         let mut writer = Vec::new();
         render(&g, &mut writer).unwrap();
         let mut s = String::new();
-        try!(Read::read_to_string(&mut &*writer, &mut s));
+        Read::read_to_string(&mut &*writer, &mut s)?;
         Ok(s)
     }
 

src/librbml/lib.rs

@@ -398,8 +398,8 @@ pub mod reader {
     }
 
     pub fn doc_at<'a>(data: &'a [u8], start: usize) -> DecodeResult<TaggedDoc<'a>> {
-        let elt_tag = try!(tag_at(data, start));
-        let elt_size = try!(tag_len_at(data, elt_tag));
+        let elt_tag = tag_at(data, start)?;
+        let elt_size = tag_len_at(data, elt_tag)?;
         let end = elt_size.next + elt_size.val;
         Ok(TaggedDoc {
             tag: elt_tag.val,
@@ -581,7 +581,7 @@ pub mod reader {
             if self.pos >= self.parent.end {
                 return Err(Expected(format!("no more documents in current node!")));
             }
-            let TaggedDoc { tag: r_tag, doc: r_doc } = try!(doc_at(self.parent.data, self.pos));
+            let TaggedDoc { tag: r_tag, doc: r_doc } = doc_at(self.parent.data, self.pos)?;
             debug!("self.parent={:?}-{:?} self.pos={:?} r_tag={:?} r_doc={:?}-{:?}",
                    self.parent.start,
                    self.parent.end,
@@ -607,12 +607,12 @@ pub mod reader {
         fn push_doc<T, F>(&mut self, exp_tag: EbmlEncoderTag, f: F) -> DecodeResult<T>
             where F: FnOnce(&mut Decoder<'doc>) -> DecodeResult<T>
         {
-            let d = try!(self.next_doc(exp_tag));
+            let d = self.next_doc(exp_tag)?;
             let old_parent = self.parent;
             let old_pos = self.pos;
             self.parent = d;
             self.pos = d.start;
-            let r = try!(f(self));
+            let r = f(self)?;
             self.parent = old_parent;
             self.pos = old_pos;
             Ok(r)
@@ -624,7 +624,7 @@ pub mod reader {
                 return Ok(0);
             }
 
-            let TaggedDoc { tag: r_tag, doc: r_doc } = try!(doc_at(self.parent.data, self.pos));
+            let TaggedDoc { tag: r_tag, doc: r_doc } = doc_at(self.parent.data, self.pos)?;
             let r = if r_tag == (EsSub8 as usize) {
                 doc_as_u8(r_doc) as usize
             } else if r_tag == (EsSub32 as usize) {
@@ -659,7 +659,7 @@ pub mod reader {
                 return Err(Expected(format!("no more documents in current node!")));
             }
 
-            let TaggedDoc { tag: r_tag, doc: r_doc } = try!(doc_at(self.parent.data, self.pos));
+            let TaggedDoc { tag: r_tag, doc: r_doc } = doc_at(self.parent.data, self.pos)?;
             let r = if first_tag as usize <= r_tag && r_tag <= last_tag as usize {
                 match r_tag - first_tag as usize {
                     0 => doc_as_u8(r_doc) as u64,
@@ -689,11 +689,11 @@ pub mod reader {
         pub fn read_opaque<R, F>(&mut self, op: F) -> DecodeResult<R>
             where F: FnOnce(&mut opaque::Decoder, Doc) -> DecodeResult<R>
         {
-            let doc = try!(self.next_doc(EsOpaque));
+            let doc = self.next_doc(EsOpaque)?;
 
             let result = {
                 let mut opaque_decoder = opaque::Decoder::new(doc.data, doc.start);
-                try!(op(&mut opaque_decoder, doc))
+                op(&mut opaque_decoder, doc)?
             };
 
             Ok(result)
@@ -718,16 +718,16 @@ pub mod reader {
             self._next_int(EsU8, EsU64)
         }
         fn read_u32(&mut self) -> DecodeResult<u32> {
-            Ok(try!(self._next_int(EsU8, EsU32)) as u32)
+            Ok(self._next_int(EsU8, EsU32)? as u32)
         }
         fn read_u16(&mut self) -> DecodeResult<u16> {
-            Ok(try!(self._next_int(EsU8, EsU16)) as u16)
+            Ok(self._next_int(EsU8, EsU16)? as u16)
         }
         fn read_u8(&mut self) -> DecodeResult<u8> {
-            Ok(doc_as_u8(try!(self.next_doc(EsU8))))
+            Ok(doc_as_u8(self.next_doc(EsU8)?))
         }
         fn read_uint(&mut self) -> DecodeResult<usize> {
-            let v = try!(self._next_int(EsU8, EsU64));
+            let v = self._next_int(EsU8, EsU64)?;
             if v > (::std::usize::MAX as u64) {
                 Err(IntTooBig(v as usize))
             } else {
@@ -736,19 +736,19 @@ pub mod reader {
         }
 
         fn read_i64(&mut self) -> DecodeResult<i64> {
-            Ok(try!(self._next_int(EsI8, EsI64)) as i64)
+            Ok(self._next_int(EsI8, EsI64)? as i64)
         }
         fn read_i32(&mut self) -> DecodeResult<i32> {
-            Ok(try!(self._next_int(EsI8, EsI32)) as i32)
+            Ok(self._next_int(EsI8, EsI32)? as i32)
         }
         fn read_i16(&mut self) -> DecodeResult<i16> {
-            Ok(try!(self._next_int(EsI8, EsI16)) as i16)
+            Ok(self._next_int(EsI8, EsI16)? as i16)
         }
         fn read_i8(&mut self) -> DecodeResult<i8> {
-            Ok(doc_as_u8(try!(self.next_doc(EsI8))) as i8)
+            Ok(doc_as_u8(self.next_doc(EsI8)?) as i8)
         }
         fn read_int(&mut self) -> DecodeResult<isize> {
-            let v = try!(self._next_int(EsI8, EsI64)) as i64;
+            let v = self._next_int(EsI8, EsI64)? as i64;
             if v > (isize::MAX as i64) || v < (isize::MIN as i64) {
                 debug!("FIXME \\#6122: Removing this makes this function miscompile");
                 Err(IntTooBig(v as usize))
@@ -758,22 +758,22 @@ pub mod reader {
         }
 
         fn read_bool(&mut self) -> DecodeResult<bool> {
-            Ok(doc_as_u8(try!(self.next_doc(EsBool))) != 0)
+            Ok(doc_as_u8(self.next_doc(EsBool)?) != 0)
         }
 
         fn read_f64(&mut self) -> DecodeResult<f64> {
-            let bits = doc_as_u64(try!(self.next_doc(EsF64)));
+            let bits = doc_as_u64(self.next_doc(EsF64)?);
             Ok(unsafe { transmute(bits) })
         }
         fn read_f32(&mut self) -> DecodeResult<f32> {
-            let bits = doc_as_u32(try!(self.next_doc(EsF32)));
+            let bits = doc_as_u32(self.next_doc(EsF32)?);
             Ok(unsafe { transmute(bits) })
         }
         fn read_char(&mut self) -> DecodeResult<char> {
-            Ok(char::from_u32(doc_as_u32(try!(self.next_doc(EsChar)))).unwrap())
+            Ok(char::from_u32(doc_as_u32(self.next_doc(EsChar)?)).unwrap())
         }
         fn read_str(&mut self) -> DecodeResult<String> {
-            Ok(try!(self.next_doc(EsStr)).as_str())
+            Ok(self.next_doc(EsStr)?.as_str())
         }
 
         // Compound types:
@@ -782,13 +782,13 @@ pub mod reader {
         {
             debug!("read_enum({})", name);
 
-            let doc = try!(self.next_doc(EsEnum));
+            let doc = self.next_doc(EsEnum)?;
 
             let (old_parent, old_pos) = (self.parent, self.pos);
             self.parent = doc;
             self.pos = self.parent.start;
 
-            let result = try!(f(self));
+            let result = f(self)?;
 
             self.parent = old_parent;
             self.pos = old_pos;
@@ -799,7 +799,7 @@ pub mod reader {
             where F: FnMut(&mut Decoder<'doc>, usize) -> DecodeResult<T>
         {
             debug!("read_enum_variant()");
-            let idx = try!(self._next_sub());
+            let idx = self._next_sub()?;
             debug!("  idx={}", idx);
 
             f(self, idx)
@@ -816,7 +816,7 @@ pub mod reader {
             where F: FnMut(&mut Decoder<'doc>, usize) -> DecodeResult<T>
         {
             debug!("read_enum_struct_variant()");
-            let idx = try!(self._next_sub());
+            let idx = self._next_sub()?;
             debug!("  idx={}", idx);
 
             f(self, idx)
@@ -904,7 +904,7 @@ pub mod reader {
         {
             debug!("read_seq()");
             self.push_doc(EsVec, move |d| {
-                let len = try!(d._next_sub());
+                let len = d._next_sub()?;
                 debug!("  len={}", len);
                 f(d, len)
             })
@@ -922,7 +922,7 @@ pub mod reader {
         {
             debug!("read_map()");
             self.push_doc(EsMap, move |d| {
-                let len = try!(d._next_sub());
+                let len = d._next_sub()?;
                 debug!("  len={}", len);
                 f(d, len)
             })
@@ -1020,10 +1020,10 @@ pub mod writer {
             assert!(tag_id >= NUM_IMPLICIT_TAGS);
 
             // Write the enum ID:
-            try!(write_tag(self.writer, tag_id));
+            write_tag(self.writer, tag_id)?;
 
             // Write a placeholder four-byte size.
-            let cur_pos = try!(self.writer.seek(SeekFrom::Current(0)));
+            let cur_pos = self.writer.seek(SeekFrom::Current(0))?;
             self.size_positions.push(cur_pos);
             let zeroes: &[u8] = &[0, 0, 0, 0];
             self.writer.write_all(zeroes)
@@ -1031,8 +1031,8 @@ pub mod writer {
 
         pub fn end_tag(&mut self) -> EncodeResult {
             let last_size_pos = self.size_positions.pop().unwrap();
-            let cur_pos = try!(self.writer.seek(SeekFrom::Current(0)));
-            try!(self.writer.seek(SeekFrom::Start(last_size_pos)));
+            let cur_pos = self.writer.seek(SeekFrom::Current(0))?;
+            self.writer.seek(SeekFrom::Start(last_size_pos))?;
             let size = (cur_pos - last_size_pos - 4) as usize;
 
             // relax the size encoding for small tags (bigger tags are costly to move).
@@ -1048,12 +1048,12 @@ pub mod writer {
                 }
 
                 // overwrite the size and data and continue
-                try!(write_vuint(self.writer, size));
-                try!(self.writer.write_all(&buf[..size]));
+                write_vuint(self.writer, size)?;
+                self.writer.write_all(&buf[..size])?;
             } else {
                 // overwrite the size with an overlong encoding and skip past the data
-                try!(write_sized_vuint(self.writer, size, 4));
-                try!(self.writer.seek(SeekFrom::Start(cur_pos)));
+                write_sized_vuint(self.writer, size, 4)?;
+                self.writer.seek(SeekFrom::Start(cur_pos))?;
             }
 
             debug!("End tag (size = {:?})", size);
@@ -1063,15 +1063,15 @@ pub mod writer {
         pub fn wr_tag<F>(&mut self, tag_id: usize, blk: F) -> EncodeResult
             where F: FnOnce() -> EncodeResult
         {
-            try!(self.start_tag(tag_id));
-            try!(blk());
+            self.start_tag(tag_id)?;
+            blk()?;
             self.end_tag()
         }
 
         pub fn wr_tagged_bytes(&mut self, tag_id: usize, b: &[u8]) -> EncodeResult {
             assert!(tag_id >= NUM_IMPLICIT_TAGS);
-            try!(write_tag(self.writer, tag_id));
-            try!(write_vuint(self.writer, b.len()));
+            write_tag(self.writer, tag_id)?;
+            write_vuint(self.writer, b.len())?;
             self.writer.write_all(b)
         }
 
@@ -1124,7 +1124,7 @@ pub mod writer {
 
         // for auto-serialization
         fn wr_tagged_raw_bytes(&mut self, tag_id: usize, b: &[u8]) -> EncodeResult {
-            try!(write_tag(self.writer, tag_id));
+            write_tag(self.writer, tag_id)?;
             self.writer.write_all(b)
         }
 
@@ -1200,11 +1200,11 @@ pub mod writer {
         pub fn emit_opaque<F>(&mut self, f: F) -> EncodeResult
             where F: FnOnce(&mut opaque::Encoder) -> EncodeResult
         {
-            try!(self.start_tag(EsOpaque as usize));
+            self.start_tag(EsOpaque as usize)?;
 
             {
                 let mut opaque_encoder = opaque::Encoder::new(self.writer);
-                try!(f(&mut opaque_encoder));
+                f(&mut opaque_encoder)?;
             }
 
             self.mark_stable_position();
@@ -1298,15 +1298,15 @@ pub mod writer {
         fn emit_enum<F>(&mut self, _name: &str, f: F) -> EncodeResult
             where F: FnOnce(&mut Encoder<'a>) -> EncodeResult
         {
-            try!(self.start_tag(EsEnum as usize));
-            try!(f(self));
+            self.start_tag(EsEnum as usize)?;
+            f(self)?;
             self.end_tag()
         }
 
         fn emit_enum_variant<F>(&mut self, _: &str, v_id: usize, _: usize, f: F) -> EncodeResult
             where F: FnOnce(&mut Encoder<'a>) -> EncodeResult
         {
-            try!(self._emit_tagged_sub(v_id));
+            self._emit_tagged_sub(v_id)?;
             f(self)
         }
 
@@ -1390,9 +1390,9 @@ pub mod writer {
                 return self.wr_tagged_bytes(EsVec as usize, &[]);
             }
 
-            try!(self.start_tag(EsVec as usize));
-            try!(self._emit_tagged_sub(len));
-            try!(f(self));
+            self.start_tag(EsVec as usize)?;
+            self._emit_tagged_sub(len)?;
+            f(self)?;
             self.end_tag()
         }
 
@@ -1400,8 +1400,8 @@ pub mod writer {
             where F: FnOnce(&mut Encoder<'a>) -> EncodeResult
         {
 
-            try!(self.start_tag(EsVecElt as usize));
-            try!(f(self));
+            self.start_tag(EsVecElt as usize)?;
+            f(self)?;
             self.end_tag()
         }
 
@@ -1413,9 +1413,9 @@ pub mod writer {
                 return self.wr_tagged_bytes(EsMap as usize, &[]);
             }
 
-            try!(self.start_tag(EsMap as usize));
-            try!(self._emit_tagged_sub(len));
-            try!(f(self));
+            self.start_tag(EsMap as usize)?;
+            self._emit_tagged_sub(len)?;
+            f(self)?;
             self.end_tag()
         }
 
@@ -1423,16 +1423,16 @@ pub mod writer {
             where F: FnOnce(&mut Encoder<'a>) -> EncodeResult
         {
 
-            try!(self.start_tag(EsMapKey as usize));
-            try!(f(self));
+            self.start_tag(EsMapKey as usize)?;
+            f(self)?;
             self.end_tag()
         }
 
         fn emit_map_elt_val<F>(&mut self, _idx: usize, f: F) -> EncodeResult
             where F: FnOnce(&mut Encoder<'a>) -> EncodeResult
         {
-            try!(self.start_tag(EsMapVal as usize));
-            try!(f(self));
+            self.start_tag(EsMapVal as usize)?;
+            f(self)?;
             self.end_tag()
         }
     }

src/librbml/opaque.rs

@@ -120,7 +120,7 @@ impl<'a> serialize::Encoder for Encoder<'a> {
     }
 
     fn emit_str(&mut self, v: &str) -> EncodeResult {
-        try!(self.emit_uint(v.len()));
+        self.emit_uint(v.len())?;
         let _ = self.cursor.write_all(v.as_bytes());
         Ok(())
     }
@@ -139,7 +139,7 @@ impl<'a> serialize::Encoder for Encoder<'a> {
                             -> EncodeResult
         where F: FnOnce(&mut Self) -> EncodeResult
     {
-        try!(self.emit_uint(v_id));
+        self.emit_uint(v_id)?;
         f(self)
     }
 
@@ -221,7 +221,7 @@ impl<'a> serialize::Encoder for Encoder<'a> {
     fn emit_seq<F>(&mut self, len: usize, f: F) -> EncodeResult
         where F: FnOnce(&mut Encoder<'a>) -> EncodeResult
     {
-        try!(self.emit_uint(len));
+        self.emit_uint(len)?;
         f(self)
     }
 
@@ -234,7 +234,7 @@ impl<'a> serialize::Encoder for Encoder<'a> {
     fn emit_map<F>(&mut self, len: usize, f: F) -> EncodeResult
         where F: FnOnce(&mut Encoder<'a>) -> EncodeResult
     {
-        try!(self.emit_uint(len));
+        self.emit_uint(len)?;
         f(self)
     }
 
@@ -356,27 +356,27 @@ impl<'a> serialize::Decoder for Decoder<'a> {
     }
 
     fn read_bool(&mut self) -> Result<bool, Self::Error> {
-        let value = try!(self.read_u8());
+        let value = self.read_u8()?;
         Ok(value != 0)
     }
 
     fn read_f64(&mut self) -> Result<f64, Self::Error> {
-        let bits = try!(self.read_u64());
+        let bits = self.read_u64()?;
         Ok(unsafe { ::std::mem::transmute(bits) })
     }
 
     fn read_f32(&mut self) -> Result<f32, Self::Error> {
-        let bits = try!(self.read_u32());
+        let bits = self.read_u32()?;
         Ok(unsafe { ::std::mem::transmute(bits) })
     }
 
     fn read_char(&mut self) -> Result<char, Self::Error> {
-        let bits = try!(self.read_u32());
+        let bits = self.read_u32()?;
         Ok(::std::char::from_u32(bits).unwrap())
     }
 
     fn read_str(&mut self) -> Result<String, Self::Error> {
-        let len = try!(self.read_uint());
+        let len = self.read_uint()?;
         let s = ::std::str::from_utf8(&self.data[self.position..self.position + len]).unwrap();
         self.position += len;
         Ok(s.to_string())
@@ -391,7 +391,7 @@ impl<'a> serialize::Decoder for Decoder<'a> {
     fn read_enum_variant<T, F>(&mut self, _: &[&str], mut f: F) -> Result<T, Self::Error>
         where F: FnMut(&mut Decoder<'a>, usize) -> Result<T, Self::Error>
     {
-        let disr = try!(self.read_uint());
+        let disr = self.read_uint()?;
         f(self, disr)
     }
 
@@ -404,7 +404,7 @@ impl<'a> serialize::Decoder for Decoder<'a> {
     fn read_enum_struct_variant<T, F>(&mut self, _: &[&str], mut f: F) -> Result<T, Self::Error>
         where F: FnMut(&mut Decoder<'a>, usize) -> Result<T, Self::Error>
     {
-        let disr = try!(self.read_uint());
+        let disr = self.read_uint()?;
         f(self, disr)
     }
 
@@ -483,7 +483,7 @@ impl<'a> serialize::Decoder for Decoder<'a> {
     fn read_seq<T, F>(&mut self, f: F) -> Result<T, Self::Error>
         where F: FnOnce(&mut Decoder<'a>, usize) -> Result<T, Self::Error>
     {
-        let len = try!(self.read_uint());
+        let len = self.read_uint()?;
         f(self, len)
     }
 
@@ -496,7 +496,7 @@ impl<'a> serialize::Decoder for Decoder<'a> {
     fn read_map<T, F>(&mut self, f: F) -> Result<T, Self::Error>
         where F: FnOnce(&mut Decoder<'a>, usize) -> Result<T, Self::Error>
     {
-        let len = try!(self.read_uint());
+        let len = self.read_uint()?;
         f(self, len)
     }
 

src/librustc/middle/check_match.rs

@@ -68,7 +68,7 @@ struct Matrix<'a>(Vec<Vec<&'a Pat>>);
 /// ++++++++++++++++++++++++++
 impl<'a> fmt::Debug for Matrix<'a> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(f, "\n"));
+        write!(f, "\n")?;
 
         let &Matrix(ref m) = self;
         let pretty_printed_matrix: Vec<Vec<String>> = m.iter().map(|row| {
@@ -85,16 +85,16 @@ impl<'a> fmt::Debug for Matrix<'a> {
 
         let total_width = column_widths.iter().cloned().sum::<usize>() + column_count * 3 + 1;
         let br = repeat('+').take(total_width).collect::<String>();
-        try!(write!(f, "{}\n", br));
+        write!(f, "{}\n", br)?;
         for row in pretty_printed_matrix {
-            try!(write!(f, "+"));
+            write!(f, "+")?;
             for (column, pat_str) in row.into_iter().enumerate() {
-                try!(write!(f, " "));
-                try!(write!(f, "{:1$}", pat_str, column_widths[column]));
-                try!(write!(f, " +"));
+                write!(f, " ")?;
+                write!(f, "{:1$}", pat_str, column_widths[column])?;
+                write!(f, " +")?;
             }
-            try!(write!(f, "\n"));
-            try!(write!(f, "{}\n", br));
+            write!(f, "\n")?;
+            write!(f, "{}\n", br)?;
         }
         Ok(())
     }

src/librustc/middle/const_eval.rs

@@ -639,14 +639,14 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &TyCtxt<'tcx>,
                 _ => {},
             }
         }
-        match try!(eval_const_expr_partial(tcx, &inner, ty_hint, fn_args)) {
+        match eval_const_expr_partial(tcx, &inner, ty_hint, fn_args)? {
           Float(f) => Float(-f),
           Integral(i) => Integral(math!(e, -i)),
           const_val => signal!(e, NegateOn(const_val)),
         }
       }
       hir::ExprUnary(hir::UnNot, ref inner) => {
-        match try!(eval_const_expr_partial(tcx, &inner, ty_hint, fn_args)) {
+        match eval_const_expr_partial(tcx, &inner, ty_hint, fn_args)? {
           Integral(i) => Integral(math!(e, !i)),
           Bool(b) => Bool(!b),
           const_val => signal!(e, NotOn(const_val)),
@@ -661,8 +661,8 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &TyCtxt<'tcx>,
         // gives us a type through a type-suffix, cast or const def type
         // we need to re-eval the other value of the BinOp if it was
         // not inferred
-        match (try!(eval_const_expr_partial(tcx, &a, ty_hint, fn_args)),
-               try!(eval_const_expr_partial(tcx, &b, b_ty, fn_args))) {
+        match (eval_const_expr_partial(tcx, &a, ty_hint, fn_args)?,
+               eval_const_expr_partial(tcx, &b, b_ty, fn_args)?) {
           (Float(a), Float(b)) => {
             match op.node {
               hir::BiAdd => Float(a + b),
@@ -744,7 +744,7 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &TyCtxt<'tcx>,
                     // we had a type hint, so we can't have an unknown type
                     None => unreachable!(),
                 };
-                try!(eval_const_expr_partial(tcx, &base, hint, fn_args))
+                eval_const_expr_partial(tcx, &base, hint, fn_args)?
             },
             Err(e) => return Err(e),
         };
@@ -781,14 +781,14 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &TyCtxt<'tcx>,
                           Some(ty) => ty_hint.checked_or(ty),
                           None => ty_hint,
                       };
-                      try!(eval_const_expr_partial(tcx, e, item_hint, None))
+                      eval_const_expr_partial(tcx, e, item_hint, None)?
                   } else {
                       signal!(e, NonConstPath);
                   }
               },
               Def::Variant(enum_def, variant_def) => {
                   if let Some(const_expr) = lookup_variant_by_id(tcx, enum_def, variant_def) {
-                      try!(eval_const_expr_partial(tcx, const_expr, ty_hint, None))
+                      eval_const_expr_partial(tcx, const_expr, ty_hint, None)?
                   } else {
                       signal!(e, NonConstPath);
                   }
@@ -810,7 +810,7 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &TyCtxt<'tcx>,
       }
       hir::ExprCall(ref callee, ref args) => {
           let sub_ty_hint = ty_hint.erase_hint();
-          let callee_val = try!(eval_const_expr_partial(tcx, callee, sub_ty_hint, fn_args));
+          let callee_val = eval_const_expr_partial(tcx, callee, sub_ty_hint, fn_args)?;
           let did = match callee_val {
               Function(did) => did,
               callee => signal!(e, CallOn(callee)),
@@ -826,27 +826,27 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &TyCtxt<'tcx>,
           let mut call_args = NodeMap();
           for (arg, arg_expr) in decl.inputs.iter().zip(args.iter()) {
               let arg_hint = ty_hint.erase_hint();
-              let arg_val = try!(eval_const_expr_partial(
+              let arg_val = eval_const_expr_partial(
                   tcx,
                   arg_expr,
                   arg_hint,
                   fn_args
-              ));
+              )?;
               debug!("const call arg: {:?}", arg);
               let old = call_args.insert(arg.pat.id, arg_val);
               assert!(old.is_none());
           }
           debug!("const call({:?})", call_args);
-          try!(eval_const_expr_partial(tcx, &result, ty_hint, Some(&call_args)))
+          eval_const_expr_partial(tcx, &result, ty_hint, Some(&call_args))?
       },
-      hir::ExprLit(ref lit) => try!(lit_to_const(&lit.node, tcx, ety, lit.span)),
+      hir::ExprLit(ref lit) => lit_to_const(&lit.node, tcx, ety, lit.span)?,
       hir::ExprBlock(ref block) => {
         match block.expr {
-            Some(ref expr) => try!(eval_const_expr_partial(tcx, &expr, ty_hint, fn_args)),
+            Some(ref expr) => eval_const_expr_partial(tcx, &expr, ty_hint, fn_args)?,
             None => unreachable!(),
         }
       }
-      hir::ExprType(ref e, _) => try!(eval_const_expr_partial(tcx, &e, ty_hint, fn_args)),
+      hir::ExprType(ref e, _) => eval_const_expr_partial(tcx, &e, ty_hint, fn_args)?,
       hir::ExprTup(_) => Tuple(e.id),
       hir::ExprStruct(..) => Struct(e.id),
       hir::ExprIndex(ref arr, ref idx) => {
@@ -854,9 +854,9 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &TyCtxt<'tcx>,
             signal!(e, IndexOpFeatureGated);
         }
         let arr_hint = ty_hint.erase_hint();
-        let arr = try!(eval_const_expr_partial(tcx, arr, arr_hint, fn_args));
+        let arr = eval_const_expr_partial(tcx, arr, arr_hint, fn_args)?;
         let idx_hint = ty_hint.checked_or(tcx.types.usize);
-        let idx = match try!(eval_const_expr_partial(tcx, idx, idx_hint, fn_args)) {
+        let idx = match eval_const_expr_partial(tcx, idx, idx_hint, fn_args)? {
             Integral(Usize(i)) => i.as_u64(tcx.sess.target.uint_type),
             Integral(_) => unreachable!(),
             _ => signal!(idx, IndexNotInt),
@@ -866,18 +866,18 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &TyCtxt<'tcx>,
             Array(_, n) if idx >= n => signal!(e, IndexOutOfBounds),
             Array(v, n) => if let hir::ExprVec(ref v) = tcx.map.expect_expr(v).node {
                 assert_eq!(n as usize as u64, n);
-                try!(eval_const_expr_partial(tcx, &v[idx as usize], ty_hint, fn_args))
+                eval_const_expr_partial(tcx, &v[idx as usize], ty_hint, fn_args)?
             } else {
                 unreachable!()
             },
 
             Repeat(_, n) if idx >= n => signal!(e, IndexOutOfBounds),
-            Repeat(elem, _) => try!(eval_const_expr_partial(
+            Repeat(elem, _) => eval_const_expr_partial(
                 tcx,
                 &tcx.map.expect_expr(elem),
                 ty_hint,
                 fn_args,
-            )),
+            )?,
 
             ByteStr(ref data) if idx >= data.len() as u64 => signal!(e, IndexOutOfBounds),
             ByteStr(data) => {
@@ -894,7 +894,7 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &TyCtxt<'tcx>,
           let len_hint = ty_hint.checked_or(tcx.types.usize);
           Repeat(
               e.id,
-              match try!(eval_const_expr_partial(tcx, &n, len_hint, fn_args)) {
+              match eval_const_expr_partial(tcx, &n, len_hint, fn_args)? {
                   Integral(Usize(i)) => i.as_u64(tcx.sess.target.uint_type),
                   Integral(_) => signal!(e, RepeatCountNotNatural),
                   _ => signal!(e, RepeatCountNotInt),
@@ -903,11 +903,11 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &TyCtxt<'tcx>,
       },
       hir::ExprTupField(ref base, index) => {
         let base_hint = ty_hint.erase_hint();
-        let c = try!(eval_const_expr_partial(tcx, base, base_hint, fn_args));
+        let c = eval_const_expr_partial(tcx, base, base_hint, fn_args)?;
         if let Tuple(tup_id) = c {
             if let hir::ExprTup(ref fields) = tcx.map.expect_expr(tup_id).node {
                 if index.node < fields.len() {
-                    try!(eval_const_expr_partial(tcx, &fields[index.node], ty_hint, fn_args))
+                    eval_const_expr_partial(tcx, &fields[index.node], ty_hint, fn_args)?
                 } else {
                     signal!(e, TupleIndexOutOfBounds);
                 }
@@ -921,14 +921,14 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &TyCtxt<'tcx>,
       hir::ExprField(ref base, field_name) => {
         let base_hint = ty_hint.erase_hint();
         // Get the base expression if it is a struct and it is constant
-        let c = try!(eval_const_expr_partial(tcx, base, base_hint, fn_args));
+        let c = eval_const_expr_partial(tcx, base, base_hint, fn_args)?;
         if let Struct(struct_id) = c {
             if let hir::ExprStruct(_, ref fields, _) = tcx.map.expect_expr(struct_id).node {
                 // Check that the given field exists and evaluate it
                 // if the idents are compared run-pass/issue-19244 fails
                 if let Some(f) = fields.iter().find(|f| f.name.node
                                                      == field_name.node) {
-                    try!(eval_const_expr_partial(tcx, &f.expr, ty_hint, fn_args))
+                    eval_const_expr_partial(tcx, &f.expr, ty_hint, fn_args)?
                 } else {
                     signal!(e, MissingStructField);
                 }
@@ -943,7 +943,7 @@ pub fn eval_const_expr_partial<'tcx>(tcx: &TyCtxt<'tcx>,
     };
 
     match (ety.map(|t| &t.sty), result) {
-        (Some(ref ty_hint), Integral(i)) => Ok(Integral(try!(infer(i, tcx, ty_hint, e.span)))),
+        (Some(ref ty_hint), Integral(i)) => Ok(Integral(infer(i, tcx, ty_hint, e.span)?)),
         (_, result) => Ok(result),
     }
 }
@@ -1105,14 +1105,14 @@ fn cast_const_int<'tcx>(tcx: &TyCtxt<'tcx>, val: ConstInt, ty: ty::Ty) -> CastRe
         ty::TyFloat(ast::FloatTy::F64) if val.is_negative() => {
             // FIXME: this could probably be prettier
             // there's no easy way to turn an `Infer` into a f64
-            let val = try!((-val).map_err(Math));
+            let val = (-val).map_err(Math)?;
             let val = val.to_u64().unwrap() as f64;
             let val = -val;
             Ok(Float(val))
         },
         ty::TyFloat(ast::FloatTy::F64) => Ok(Float(val.to_u64().unwrap() as f64)),
         ty::TyFloat(ast::FloatTy::F32) if val.is_negative() => {
-            let val = try!((-val).map_err(Math));
+            let val = (-val).map_err(Math)?;
             let val = val.to_u64().unwrap() as f32;
             let val = -val;
             Ok(Float(val as f64))

src/librustc/middle/dataflow.rs

@@ -152,10 +152,10 @@ impl<'a, 'tcx, O:DataFlowOperator> pprust::PpAnn for DataFlowContext<'a, 'tcx, O
                 "".to_string()
             };
 
-            try!(ps.synth_comment(
+            ps.synth_comment(
                 format!("id {}: {}{}{}{}", id, entry_str,
-                        gens_str, action_kills_str, scope_kills_str)));
-            try!(pp::space(&mut ps.s));
+                        gens_str, action_kills_str, scope_kills_str))?;
+            pp::space(&mut ps.s)?;
         }
         Ok(())
     }
@@ -534,9 +534,9 @@ impl<'a, 'tcx, O:DataFlowOperator+Clone+'static> DataFlowContext<'a, 'tcx, O> {
     fn pretty_print_to<'b>(&self, wr: Box<io::Write + 'b>,
                            blk: &hir::Block) -> io::Result<()> {
         let mut ps = pprust::rust_printer_annotated(wr, self, None);
-        try!(ps.cbox(pprust::indent_unit));
-        try!(ps.ibox(0));
-        try!(ps.print_block(blk));
+        ps.cbox(pprust::indent_unit)?;
+        ps.ibox(0)?;
+        ps.print_block(blk)?;
         pp::eof(&mut ps.s)
     }
 }

src/librustc/middle/def_id.rs

@@ -55,8 +55,8 @@ pub struct DefId {
 
 impl fmt::Debug for DefId {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(f, "DefId {{ krate: {:?}, node: {:?}",
-                    self.krate, self.index));
+        write!(f, "DefId {{ krate: {:?}, node: {:?}",
+                    self.krate, self.index)?;
 
         // Unfortunately, there seems to be no way to attempt to print
         // a path for a def-id, so I'll just make a best effort for now
@@ -64,12 +64,12 @@ impl fmt::Debug for DefId {
         if self.is_local() { // (1)
             // (1) side-step fact that not all external things have paths at
             // the moment, such as type parameters
-            try!(ty::tls::with_opt(|opt_tcx| {
+            ty::tls::with_opt(|opt_tcx| {
                 if let Some(tcx) = opt_tcx {
-                    try!(write!(f, " => {}", tcx.item_path_str(*self)));
+                    write!(f, " => {}", tcx.item_path_str(*self))?;
                 }
                 Ok(())
-            }));
+            })?;
         }
 
         write!(f, " }}")

src/librustc/middle/expr_use_visitor.rs

@@ -1182,7 +1182,7 @@ impl<'d,'t,'a,'tcx> ExprUseVisitor<'d,'t,'a,'tcx> {
         // Create the cmt for the variable being borrowed, from the
         // caller's perspective
         let var_id = upvar_def.var_id();
-        let var_ty = try!(self.typer.node_ty(var_id));
+        let var_ty = self.typer.node_ty(var_id)?;
         self.mc.cat_def(closure_id, closure_span, var_ty, upvar_def)
     }
 }

src/librustc/middle/infer/bivariate.rs

@@ -86,12 +86,12 @@ impl<'a, 'tcx> TypeRelation<'a, 'tcx> for Bivariate<'a, 'tcx> {
             }
 
             (&ty::TyInfer(TyVar(a_id)), _) => {
-                try!(self.fields.instantiate(b, BiTo, a_id));
+                self.fields.instantiate(b, BiTo, a_id)?;
                 Ok(a)
             }
 
             (_, &ty::TyInfer(TyVar(b_id))) => {
-                try!(self.fields.instantiate(a, BiTo, b_id));
+                self.fields.instantiate(a, BiTo, b_id)?;
                 Ok(a)
             }
 
@@ -111,7 +111,7 @@ impl<'a, 'tcx> TypeRelation<'a, 'tcx> for Bivariate<'a, 'tcx> {
     {
         let a1 = self.tcx().erase_late_bound_regions(a);
         let b1 = self.tcx().erase_late_bound_regions(b);
-        let c = try!(self.relate(&a1, &b1));
+        let c = self.relate(&a1, &b1)?;
         Ok(ty::Binder(c))
     }
 }

src/librustc/middle/infer/combine.rs

@@ -70,10 +70,10 @@ pub fn super_combine_tys<'a,'tcx:'a,R>(infcx: &InferCtxt<'a, 'tcx>,
     match (&a.sty, &b.sty) {
         // Relate integral variables to other types
         (&ty::TyInfer(ty::IntVar(a_id)), &ty::TyInfer(ty::IntVar(b_id))) => {
-            try!(infcx.int_unification_table
+            infcx.int_unification_table
                       .borrow_mut()
                       .unify_var_var(a_id, b_id)
-                      .map_err(|e| int_unification_error(a_is_expected, e)));
+                      .map_err(|e| int_unification_error(a_is_expected, e))?;
             Ok(a)
         }
         (&ty::TyInfer(ty::IntVar(v_id)), &ty::TyInt(v)) => {
@@ -91,10 +91,10 @@ pub fn super_combine_tys<'a,'tcx:'a,R>(infcx: &InferCtxt<'a, 'tcx>,
 
         // Relate floating-point variables to other types
         (&ty::TyInfer(ty::FloatVar(a_id)), &ty::TyInfer(ty::FloatVar(b_id))) => {
-            try!(infcx.float_unification_table
+            infcx.float_unification_table
                       .borrow_mut()
                       .unify_var_var(a_id, b_id)
-                      .map_err(|e| float_unification_error(relation.a_is_expected(), e)));
+                      .map_err(|e| float_unification_error(relation.a_is_expected(), e))?;
             Ok(a)
         }
         (&ty::TyInfer(ty::FloatVar(v_id)), &ty::TyFloat(v)) => {
@@ -123,11 +123,11 @@ fn unify_integral_variable<'a,'tcx>(infcx: &InferCtxt<'a,'tcx>,
                                     val: ty::IntVarValue)
                                     -> RelateResult<'tcx, Ty<'tcx>>
 {
-    try!(infcx
+    infcx
          .int_unification_table
          .borrow_mut()
          .unify_var_value(vid, val)
-         .map_err(|e| int_unification_error(vid_is_expected, e)));
+         .map_err(|e| int_unification_error(vid_is_expected, e))?;
     match val {
         IntType(v) => Ok(infcx.tcx.mk_mach_int(v)),
         UintType(v) => Ok(infcx.tcx.mk_mach_uint(v)),
@@ -140,11 +140,11 @@ fn unify_float_variable<'a,'tcx>(infcx: &InferCtxt<'a,'tcx>,
                                  val: ast::FloatTy)
                                  -> RelateResult<'tcx, Ty<'tcx>>
 {
-    try!(infcx
+    infcx
          .float_unification_table
          .borrow_mut()
          .unify_var_value(vid, val)
-         .map_err(|e| float_unification_error(vid_is_expected, e)));
+         .map_err(|e| float_unification_error(vid_is_expected, e))?;
     Ok(infcx.tcx.mk_mach_float(val))
 }
 
@@ -229,10 +229,10 @@ impl<'a, 'tcx> CombineFields<'a, 'tcx> {
                 Some(t) => t, // ...already instantiated.
                 None => {     // ...not yet instantiated:
                     // Generalize type if necessary.
-                    let generalized_ty = try!(match dir {
+                    let generalized_ty = match dir {
                         EqTo => self.generalize(a_ty, b_vid, false),
                         BiTo | SupertypeOf | SubtypeOf => self.generalize(a_ty, b_vid, true),
-                    });
+                    }?;
                     debug!("instantiate(a_ty={:?}, dir={:?}, \
                                         b_vid={:?}, generalized_ty={:?})",
                            a_ty, dir, b_vid,
@@ -252,12 +252,12 @@ impl<'a, 'tcx> CombineFields<'a, 'tcx> {
             // relations wind up attributed to the same spans. We need
             // to associate causes/spans with each of the relations in
             // the stack to get this right.
-            try!(match dir {
+            match dir {
                 BiTo => self.bivariate().relate(&a_ty, &b_ty),
                 EqTo => self.equate().relate(&a_ty, &b_ty),
                 SubtypeOf => self.sub().relate(&a_ty, &b_ty),
                 SupertypeOf => self.sub().relate_with_variance(ty::Contravariant, &a_ty, &b_ty),
-            });
+            }?;
         }
 
         Ok(())

src/librustc/middle/infer/equate.rs

@@ -59,17 +59,17 @@ impl<'a, 'tcx> TypeRelation<'a,'tcx> for Equate<'a, 'tcx> {
             }
 
             (&ty::TyInfer(TyVar(a_id)), _) => {
-                try!(self.fields.instantiate(b, EqTo, a_id));
+                self.fields.instantiate(b, EqTo, a_id)?;
                 Ok(a)
             }
 
             (_, &ty::TyInfer(TyVar(b_id))) => {
-                try!(self.fields.instantiate(a, EqTo, b_id));
+                self.fields.instantiate(a, EqTo, b_id)?;
                 Ok(a)
             }
 
             _ => {
-                try!(combine::super_combine_tys(self.fields.infcx, self, a, b));
+                combine::super_combine_tys(self.fields.infcx, self, a, b)?;
                 Ok(a)
             }
         }
@@ -89,7 +89,7 @@ impl<'a, 'tcx> TypeRelation<'a,'tcx> for Equate<'a, 'tcx> {
                   -> RelateResult<'tcx, ty::Binder<T>>
         where T: Relate<'a, 'tcx>
     {
-        try!(self.fields.higher_ranked_sub(a, b));
+        self.fields.higher_ranked_sub(a, b)?;
         self.fields.higher_ranked_sub(b, a)
     }
 }

src/librustc/middle/infer/glb.rs

@@ -78,8 +78,8 @@ impl<'a, 'tcx> LatticeDir<'a,'tcx> for Glb<'a, 'tcx> {
 
     fn relate_bound(&self, v: Ty<'tcx>, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, ()> {
         let mut sub = self.fields.sub();
-        try!(sub.relate(&v, &a));
-        try!(sub.relate(&v, &b));
+        sub.relate(&v, &a)?;
+        sub.relate(&v, &b)?;
         Ok(())
     }
 }

src/librustc/middle/infer/higher_ranked/mod.rs

@@ -75,7 +75,7 @@ impl<'a,'tcx> HigherRankedRelations<'a,'tcx> for CombineFields<'a,'tcx> {
             debug!("b_prime={:?}", b_prime);
 
             // Compare types now that bound regions have been replaced.
-            let result = try!(self.sub().relate(&a_prime, &b_prime));
+            let result = self.sub().relate(&a_prime, &b_prime)?;
 
             // Presuming type comparison succeeds, we need to check
             // that the skolemized regions do not "leak".
@@ -118,7 +118,7 @@ impl<'a,'tcx> HigherRankedRelations<'a,'tcx> for CombineFields<'a,'tcx> {
 
             // Collect constraints.
             let result0 =
-                try!(self.lub().relate(&a_with_fresh, &b_with_fresh));
+                self.lub().relate(&a_with_fresh, &b_with_fresh)?;
             let result0 =
                 self.infcx.resolve_type_vars_if_possible(&result0);
             debug!("lub result0 = {:?}", result0);
@@ -212,7 +212,7 @@ impl<'a,'tcx> HigherRankedRelations<'a,'tcx> for CombineFields<'a,'tcx> {
 
             // Collect constraints.
             let result0 =
-                try!(self.glb().relate(&a_with_fresh, &b_with_fresh));
+                self.glb().relate(&a_with_fresh, &b_with_fresh)?;
             let result0 =
                 self.infcx.resolve_type_vars_if_possible(&result0);
             debug!("glb result0 = {:?}", result0);

src/librustc/middle/infer/lattice.rs

@@ -66,14 +66,14 @@ pub fn super_lattice_tys<'a,'tcx,L:LatticeDir<'a,'tcx>>(this: &mut L,
         (&ty::TyInfer(TyVar(..)), &ty::TyInfer(TyVar(..)))
             if infcx.type_var_diverges(a) && infcx.type_var_diverges(b) => {
             let v = infcx.next_diverging_ty_var();
-            try!(this.relate_bound(v, a, b));
+            this.relate_bound(v, a, b)?;
             Ok(v)
         }
 
         (&ty::TyInfer(TyVar(..)), _) |
         (_, &ty::TyInfer(TyVar(..))) => {
             let v = infcx.next_ty_var();
-            try!(this.relate_bound(v, a, b));
+            this.relate_bound(v, a, b)?;
             Ok(v)
         }
 

src/librustc/middle/infer/lub.rs

@@ -78,8 +78,8 @@ impl<'a, 'tcx> LatticeDir<'a,'tcx> for Lub<'a, 'tcx> {
 
     fn relate_bound(&self, v: Ty<'tcx>, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, ()> {
         let mut sub = self.fields.sub();
-        try!(sub.relate(&a, &v));
-        try!(sub.relate(&b, &v));
+        sub.relate(&a, &v)?;
+        sub.relate(&b, &v)?;
         Ok(())
     }
 }

src/librustc/middle/infer/mod.rs

@@ -960,7 +960,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             let (ty::EquatePredicate(a, b), skol_map) =
                 self.skolemize_late_bound_regions(predicate, snapshot);
             let origin = TypeOrigin::EquatePredicate(span);
-            let () = try!(mk_eqty(self, false, origin, a, b));
+            let () = mk_eqty(self, false, origin, a, b)?;
             self.leak_check(&skol_map, snapshot)
         })
     }

src/librustc/middle/infer/sub.rs

@@ -75,13 +75,13 @@ impl<'a, 'tcx> TypeRelation<'a, 'tcx> for Sub<'a, 'tcx> {
                 Ok(a)
             }
             (&ty::TyInfer(TyVar(a_id)), _) => {
-                try!(self.fields
+                self.fields
                          .switch_expected()
-                         .instantiate(b, SupertypeOf, a_id));
+                         .instantiate(b, SupertypeOf, a_id)?;
                 Ok(a)
             }
             (_, &ty::TyInfer(TyVar(b_id))) => {
-                try!(self.fields.instantiate(a, SubtypeOf, b_id));
+                self.fields.instantiate(a, SubtypeOf, b_id)?;
                 Ok(a)
             }
 
@@ -90,7 +90,7 @@ impl<'a, 'tcx> TypeRelation<'a, 'tcx> for Sub<'a, 'tcx> {
             }
 
             _ => {
-                try!(combine::super_combine_tys(self.fields.infcx, self, a, b));
+                combine::super_combine_tys(self.fields.infcx, self, a, b)?;
                 Ok(a)
             }
         }

src/librustc/middle/liveness.rs

@@ -686,7 +686,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
         for var_idx in 0..self.ir.num_vars {
             let idx = node_base_idx + var_idx;
             if test(idx).is_valid() {
-                try!(write!(wr, " {:?}", Variable(var_idx)));
+                write!(wr, " {:?}", Variable(var_idx))?;
             }
         }
         Ok(())

src/librustc/middle/mem_categorization.rs

@@ -378,7 +378,7 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
     }
 
     fn expr_ty_adjusted(&self, expr: &hir::Expr) -> McResult<Ty<'tcx>> {
-        let unadjusted_ty = try!(self.expr_ty(expr));
+        let unadjusted_ty = self.expr_ty(expr)?;
         Ok(unadjusted_ty.adjust(
             self.tcx(), expr.span, expr.id,
             self.typer.adjustments().get(&expr.id),
@@ -390,7 +390,7 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
     }
 
     fn pat_ty(&self, pat: &hir::Pat) -> McResult<Ty<'tcx>> {
-        let base_ty = try!(self.typer.node_ty(pat.id));
+        let base_ty = self.typer.node_ty(pat.id)?;
         // FIXME (Issue #18207): This code detects whether we are
         // looking at a `ref x`, and if so, figures out what the type
         // *being borrowed* is.  But ideally we would put in a more
@@ -436,7 +436,7 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
                                adjustment,
                                expr);
                         // Result is an rvalue.
-                        let expr_ty = try!(self.expr_ty_adjusted(expr));
+                        let expr_ty = self.expr_ty_adjusted(expr)?;
                         Ok(self.cat_rvalue_node(expr.id(), expr.span(), expr_ty))
                     }
                 }
@@ -448,12 +448,12 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
                                expr: &hir::Expr,
                                autoderefs: usize)
                                -> McResult<cmt<'tcx>> {
-        let mut cmt = try!(self.cat_expr_unadjusted(expr));
+        let mut cmt = self.cat_expr_unadjusted(expr)?;
         debug!("cat_expr_autoderefd: autoderefs={}, cmt={:?}",
                autoderefs,
                cmt);
         for deref in 1..autoderefs + 1 {
-            cmt = try!(self.cat_deref(expr, cmt, deref, None));
+            cmt = self.cat_deref(expr, cmt, deref, None)?;
         }
         return Ok(cmt);
     }
@@ -461,15 +461,15 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
     pub fn cat_expr_unadjusted(&self, expr: &hir::Expr) -> McResult<cmt<'tcx>> {
         debug!("cat_expr: id={} expr={:?}", expr.id, expr);
 
-        let expr_ty = try!(self.expr_ty(expr));
+        let expr_ty = self.expr_ty(expr)?;
         match expr.node {
           hir::ExprUnary(hir::UnDeref, ref e_base) => {
-            let base_cmt = try!(self.cat_expr(&e_base));
+            let base_cmt = self.cat_expr(&e_base)?;
             self.cat_deref(expr, base_cmt, 0, None)
           }
 
           hir::ExprField(ref base, f_name) => {
-            let base_cmt = try!(self.cat_expr(&base));
+            let base_cmt = self.cat_expr(&base)?;
             debug!("cat_expr(cat_field): id={} expr={:?} base={:?}",
                    expr.id,
                    expr,
@@ -478,7 +478,7 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
           }
 
           hir::ExprTupField(ref base, idx) => {
-            let base_cmt = try!(self.cat_expr(&base));
+            let base_cmt = self.cat_expr(&base)?;
             Ok(self.cat_tup_field(expr, base_cmt, idx.node, expr_ty))
           }
 
@@ -509,7 +509,7 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
                     self.cat_deref_common(expr, base_cmt, 1, elem_ty, Some(context), true)
                 }
                 None => {
-                    self.cat_index(expr, try!(self.cat_expr(&base)), context)
+                    self.cat_index(expr, self.cat_expr(&base)?, context)
                 }
             }
           }
@@ -575,7 +575,7 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
           }
 
           Def::Upvar(_, var_id, _, fn_node_id) => {
-              let ty = try!(self.node_ty(fn_node_id));
+              let ty = self.node_ty(fn_node_id)?;
               match ty.sty {
                   ty::TyClosure(closure_id, _) => {
                       match self.typer.closure_kind(closure_id) {
@@ -649,7 +649,7 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
 
         let upvar_id = ty::UpvarId { var_id: var_id,
                                      closure_expr_id: fn_node_id };
-        let var_ty = try!(self.node_ty(var_id));
+        let var_ty = self.node_ty(var_id)?;
 
         // Mutability of original variable itself
         let var_mutbl = MutabilityCategory::from_local(self.tcx(), var_id);
@@ -921,7 +921,7 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
                                     implicit: bool)
                                     -> McResult<cmt<'tcx>>
     {
-        let (m, cat) = match try!(deref_kind(base_cmt.ty, deref_context)) {
+        let (m, cat) = match deref_kind(base_cmt.ty, deref_context)? {
             deref_ptr(ptr) => {
                 let ptr = if implicit {
                     match ptr {
@@ -1030,7 +1030,7 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
                              context: InteriorOffsetKind)
                              -> McResult<cmt<'tcx>>
     {
-        let ret = match try!(deref_kind(base_cmt.ty, Some(context))) {
+        let ret = match deref_kind(base_cmt.ty, Some(context))? {
             deref_ptr(ptr) => {
                 // for unique ptrs, we inherit mutability from the
                 // owning reference.
@@ -1069,13 +1069,13 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
                              vec_cmt: cmt<'tcx>,
                              slice_pat: &hir::Pat)
                              -> McResult<(cmt<'tcx>, hir::Mutability, ty::Region)> {
-        let slice_ty = try!(self.node_ty(slice_pat.id));
+        let slice_ty = self.node_ty(slice_pat.id)?;
         let (slice_mutbl, slice_r) = vec_slice_info(self.tcx(),
                                                     slice_pat,
                                                     slice_ty);
         let context = InteriorOffsetKind::Pattern;
-        let cmt_vec = try!(self.deref_vec(slice_pat, vec_cmt, context));
-        let cmt_slice = try!(self.cat_index(slice_pat, cmt_vec, context));
+        let cmt_vec = self.deref_vec(slice_pat, vec_cmt, context)?;
+        let cmt_slice = self.cat_index(slice_pat, cmt_vec, context)?;
         return Ok((cmt_slice, slice_mutbl, slice_r));
 
         /// In a pattern like [a, b, ..c], normally `c` has slice type, but if you have [a, b,
@@ -1235,29 +1235,29 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
                 Some(Def::Variant(..)) => {
                     // variant(x, y, z)
                     for (i, subpat) in subpats.iter().enumerate() {
-                        let subpat_ty = try!(self.pat_ty(&subpat)); // see (*2)
+                        let subpat_ty = self.pat_ty(&subpat)?; // see (*2)
 
                         let subcmt =
                             self.cat_imm_interior(
                                 pat, cmt.clone(), subpat_ty,
                                 InteriorField(PositionalField(i)));
 
-                        try!(self.cat_pattern_(subcmt, &subpat, op));
+                        self.cat_pattern_(subcmt, &subpat, op)?;
                     }
                 }
                 Some(Def::Struct(..)) => {
                     for (i, subpat) in subpats.iter().enumerate() {
-                        let subpat_ty = try!(self.pat_ty(&subpat)); // see (*2)
+                        let subpat_ty = self.pat_ty(&subpat)?; // see (*2)
                         let cmt_field =
                             self.cat_imm_interior(
                                 pat, cmt.clone(), subpat_ty,
                                 InteriorField(PositionalField(i)));
-                        try!(self.cat_pattern_(cmt_field, &subpat, op));
+                        self.cat_pattern_(cmt_field, &subpat, op)?;
                     }
                 }
                 Some(Def::Const(..)) | Some(Def::AssociatedConst(..)) => {
                     for subpat in subpats {
-                        try!(self.cat_pattern_(cmt.clone(), &subpat, op));
+                        self.cat_pattern_(cmt.clone(), &subpat, op)?;
                     }
                 }
                 _ => {
@@ -1273,27 +1273,27 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
           }
 
           PatKind::Ident(_, _, Some(ref subpat)) => {
-              try!(self.cat_pattern_(cmt, &subpat, op));
+              self.cat_pattern_(cmt, &subpat, op)?;
           }
 
           PatKind::Struct(_, ref field_pats, _) => {
             // {f1: p1, ..., fN: pN}
             for fp in field_pats {
-                let field_ty = try!(self.pat_ty(&fp.node.pat)); // see (*2)
+                let field_ty = self.pat_ty(&fp.node.pat)?; // see (*2)
                 let cmt_field = self.cat_field(pat, cmt.clone(), fp.node.name, field_ty);
-                try!(self.cat_pattern_(cmt_field, &fp.node.pat, op));
+                self.cat_pattern_(cmt_field, &fp.node.pat, op)?;
             }
           }
 
           PatKind::Tup(ref subpats) => {
             // (p1, ..., pN)
             for (i, subpat) in subpats.iter().enumerate() {
-                let subpat_ty = try!(self.pat_ty(&subpat)); // see (*2)
+                let subpat_ty = self.pat_ty(&subpat)?; // see (*2)
                 let subcmt =
                     self.cat_imm_interior(
                         pat, cmt.clone(), subpat_ty,
                         InteriorField(PositionalField(i)));
-                try!(self.cat_pattern_(subcmt, &subpat, op));
+                self.cat_pattern_(subcmt, &subpat, op)?;
             }
           }
 
@@ -1301,24 +1301,24 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
             // box p1, &p1, &mut p1.  we can ignore the mutability of
             // PatKind::Ref since that information is already contained
             // in the type.
-            let subcmt = try!(self.cat_deref(pat, cmt, 0, None));
-              try!(self.cat_pattern_(subcmt, &subpat, op));
+            let subcmt = self.cat_deref(pat, cmt, 0, None)?;
+              self.cat_pattern_(subcmt, &subpat, op)?;
           }
 
           PatKind::Vec(ref before, ref slice, ref after) => {
               let context = InteriorOffsetKind::Pattern;
-              let vec_cmt = try!(self.deref_vec(pat, cmt, context));
-              let elt_cmt = try!(self.cat_index(pat, vec_cmt, context));
+              let vec_cmt = self.deref_vec(pat, cmt, context)?;
+              let elt_cmt = self.cat_index(pat, vec_cmt, context)?;
               for before_pat in before {
-                  try!(self.cat_pattern_(elt_cmt.clone(), &before_pat, op));
+                  self.cat_pattern_(elt_cmt.clone(), &before_pat, op)?;
               }
               if let Some(ref slice_pat) = *slice {
-                  let slice_ty = try!(self.pat_ty(&slice_pat));
+                  let slice_ty = self.pat_ty(&slice_pat)?;
                   let slice_cmt = self.cat_rvalue_node(pat.id(), pat.span(), slice_ty);
-                  try!(self.cat_pattern_(slice_cmt, &slice_pat, op));
+                  self.cat_pattern_(slice_cmt, &slice_pat, op)?;
               }
               for after_pat in after {
-                  try!(self.cat_pattern_(elt_cmt.clone(), &after_pat, op));
+                  self.cat_pattern_(elt_cmt.clone(), &after_pat, op)?;
               }
           }
 

src/librustc/middle/region.rs

@@ -41,15 +41,15 @@ pub struct CodeExtent(u32);
 
 impl fmt::Debug for CodeExtent {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(f, "CodeExtent({:?}", self.0));
+        write!(f, "CodeExtent({:?}", self.0)?;
 
-        try!(ty::tls::with_opt(|opt_tcx| {
+        ty::tls::with_opt(|opt_tcx| {
             if let Some(tcx) = opt_tcx {
                 let data = tcx.region_maps.code_extents.borrow()[self.0 as usize];
-                try!(write!(f, "/{:?}", data));
+                write!(f, "/{:?}", data)?;
             }
             Ok(())
-        }));
+        })?;
 
         write!(f, ")")
     }

src/librustc/middle/resolve_lifetime.rs

@@ -102,7 +102,7 @@ pub fn krate(sess: &Session,
     let _task = hir_map.dep_graph.in_task(DepNode::ResolveLifetimes);
     let krate = hir_map.krate();
     let mut named_region_map = NodeMap();
-    try!(sess.track_errors(|| {
+    sess.track_errors(|| {
         krate.visit_all_items(&mut LifetimeContext {
             sess: sess,
             named_region_map: &mut named_region_map,
@@ -111,7 +111,7 @@ pub fn krate(sess: &Session,
             trait_ref_hack: false,
             labels_in_fn: vec![],
         });
-    }));
+    })?;
     Ok(named_region_map)
 }
 

src/librustc/middle/traits/fulfill.rs

@@ -211,7 +211,7 @@ impl<'tcx> FulfillmentContext<'tcx> {
                                    infcx: &InferCtxt<'a,'tcx>)
                                    -> Result<(),Vec<FulfillmentError<'tcx>>>
     {
-        try!(self.select_where_possible(infcx));
+        self.select_where_possible(infcx)?;
         let errors: Vec<_> =
             self.predicates.to_errors(CodeAmbiguity)
                            .into_iter()

src/librustc/middle/traits/select.rs

@@ -320,12 +320,12 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         let _task = self.tcx().dep_graph.in_task(dep_node);
 
         let stack = self.push_stack(TraitObligationStackList::empty(), obligation);
-        match try!(self.candidate_from_obligation(&stack)) {
+        match self.candidate_from_obligation(&stack)? {
             None => {
                 self.consider_unification_despite_ambiguity(obligation);
                 Ok(None)
             }
-            Some(candidate) => Ok(Some(try!(self.confirm_candidate(obligation, candidate)))),
+            Some(candidate) => Ok(Some(self.confirm_candidate(obligation, candidate)?)),
         }
     }
 
@@ -786,7 +786,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             return Ok(None);
         }
 
-        let candidate_set = try!(self.assemble_candidates(stack));
+        let candidate_set = self.assemble_candidates(stack)?;
 
         if candidate_set.ambiguous {
             debug!("candidate set contains ambig");
@@ -1034,19 +1034,19 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
                 // User-defined copy impls are permitted, but only for
                 // structs and enums.
-                try!(self.assemble_candidates_from_impls(obligation, &mut candidates));
+                self.assemble_candidates_from_impls(obligation, &mut candidates)?;
 
                 // For other types, we'll use the builtin rules.
-                try!(self.assemble_builtin_bound_candidates(ty::BoundCopy,
+                self.assemble_builtin_bound_candidates(ty::BoundCopy,
                                                             obligation,
-                                                            &mut candidates));
+                                                            &mut candidates)?;
             }
             Some(bound @ ty::BoundSized) => {
                 // Sized is never implementable by end-users, it is
                 // always automatically computed.
-                try!(self.assemble_builtin_bound_candidates(bound,
+                self.assemble_builtin_bound_candidates(bound,
                                                             obligation,
-                                                            &mut candidates));
+                                                            &mut candidates)?;
             }
 
             None if self.tcx().lang_items.unsize_trait() ==
@@ -1057,19 +1057,19 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             Some(ty::BoundSend) |
             Some(ty::BoundSync) |
             None => {
-                try!(self.assemble_closure_candidates(obligation, &mut candidates));
-                try!(self.assemble_fn_pointer_candidates(obligation, &mut candidates));
-                try!(self.assemble_candidates_from_impls(obligation, &mut candidates));
+                self.assemble_closure_candidates(obligation, &mut candidates)?;
+                self.assemble_fn_pointer_candidates(obligation, &mut candidates)?;
+                self.assemble_candidates_from_impls(obligation, &mut candidates)?;
                 self.assemble_candidates_from_object_ty(obligation, &mut candidates);
             }
         }
 
         self.assemble_candidates_from_projected_tys(obligation, &mut candidates);
-        try!(self.assemble_candidates_from_caller_bounds(stack, &mut candidates));
+        self.assemble_candidates_from_caller_bounds(stack, &mut candidates)?;
         // Default implementations have lower priority, so we only
         // consider triggering a default if there is no other impl that can apply.
         if candidates.vec.is_empty() {
-            try!(self.assemble_candidates_from_default_impls(obligation, &mut candidates));
+            self.assemble_candidates_from_default_impls(obligation, &mut candidates)?;
         }
         debug!("candidate list size: {}", candidates.vec.len());
         Ok(candidates)
@@ -2044,7 +2044,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         match candidate {
             BuiltinCandidate(builtin_bound) => {
                 Ok(VtableBuiltin(
-                    try!(self.confirm_builtin_candidate(obligation, builtin_bound))))
+                    self.confirm_builtin_candidate(obligation, builtin_bound)?))
             }
 
             ParamCandidate(param) => {
@@ -2064,13 +2064,13 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
             ImplCandidate(impl_def_id) => {
                 let vtable_impl =
-                    try!(self.confirm_impl_candidate(obligation, impl_def_id));
+                    self.confirm_impl_candidate(obligation, impl_def_id)?;
                 Ok(VtableImpl(vtable_impl))
             }
 
             ClosureCandidate(closure_def_id, substs) => {
                 let vtable_closure =
-                    try!(self.confirm_closure_candidate(obligation, closure_def_id, substs));
+                    self.confirm_closure_candidate(obligation, closure_def_id, substs)?;
                 Ok(VtableClosure(vtable_closure))
             }
 
@@ -2090,7 +2090,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
             FnPointerCandidate => {
                 let fn_type =
-                    try!(self.confirm_fn_pointer_candidate(obligation));
+                    self.confirm_fn_pointer_candidate(obligation)?;
                 Ok(VtableFnPointer(fn_type))
             }
 
@@ -2100,7 +2100,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             }
 
             BuiltinUnsizeCandidate => {
-                let data = try!(self.confirm_builtin_unsize_candidate(obligation));
+                let data = self.confirm_builtin_unsize_candidate(obligation)?;
                 Ok(VtableBuiltin(data))
             }
         }
@@ -2152,7 +2152,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         debug!("confirm_builtin_candidate({:?})",
                obligation);
 
-        match try!(self.builtin_bound(bound, obligation)) {
+        match self.builtin_bound(bound, obligation)? {
             If(nested) => Ok(self.vtable_builtin_data(obligation, bound, nested)),
             AmbiguousBuiltin | ParameterBuiltin => {
                 self.tcx().sess.span_bug(
@@ -2421,9 +2421,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                                                     util::TupleArgumentsFlag::Yes)
             .map_bound(|(trait_ref, _)| trait_ref);
 
-        try!(self.confirm_poly_trait_refs(obligation.cause.clone(),
+        self.confirm_poly_trait_refs(obligation.cause.clone(),
                                           obligation.predicate.to_poly_trait_ref(),
-                                          trait_ref));
+                                          trait_ref)?;
         Ok(self_ty)
     }
 
@@ -2449,9 +2449,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                trait_ref,
                obligations);
 
-        try!(self.confirm_poly_trait_refs(obligation.cause.clone(),
+        self.confirm_poly_trait_refs(obligation.cause.clone(),
                                           obligation.predicate.to_poly_trait_ref(),
-                                          trait_ref));
+                                          trait_ref)?;
 
         Ok(VtableClosureData {
             closure_def_id: closure_def_id,
@@ -2795,7 +2795,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                                     where_clause_trait_ref: ty::PolyTraitRef<'tcx>)
                                     -> Result<Vec<PredicateObligation<'tcx>>,()>
     {
-        try!(self.match_poly_trait_ref(obligation, where_clause_trait_ref));
+        self.match_poly_trait_ref(obligation, where_clause_trait_ref)?;
         Ok(Vec::new())
     }
 

src/librustc/middle/traits/util.rs

@@ -418,7 +418,7 @@ pub fn predicate_for_builtin_bound<'tcx>(
     param_ty: Ty<'tcx>)
     -> Result<PredicateObligation<'tcx>, ErrorReported>
 {
-    let trait_ref = try!(trait_ref_for_builtin_bound(tcx, builtin_bound, param_ty));
+    let trait_ref = trait_ref_for_builtin_bound(tcx, builtin_bound, param_ty)?;
     Ok(predicate_for_trait_ref(cause, trait_ref, recursion_depth))
 }
 

src/librustc/middle/ty/_match.rs

@@ -91,6 +91,6 @@ impl<'a, 'tcx> TypeRelation<'a, 'tcx> for Match<'a, 'tcx> {
                   -> RelateResult<'tcx, ty::Binder<T>>
         where T: Relate<'a,'tcx>
     {
-        Ok(ty::Binder(try!(self.relate(a.skip_binder(), b.skip_binder()))))
+        Ok(ty::Binder(self.relate(a.skip_binder(), b.skip_binder())?))
     }
 }

src/librustc/middle/ty/mod.rs

@@ -1473,7 +1473,7 @@ impl<'tcx> Encodable for AdtDef<'tcx> {
 
 impl<'tcx> Decodable for AdtDef<'tcx> {
     fn decode<D: Decoder>(d: &mut D) -> Result<AdtDef<'tcx>, D::Error> {
-        let def_id: DefId = try!{ Decodable::decode(d) };
+        let def_id: DefId = Decodable::decode(d)?;
 
         cstore::tls::with_decoding_context(d, |dcx, _| {
             let def_id = dcx.translate_def_id(def_id);

src/librustc/middle/ty/relate.rs

@@ -108,7 +108,7 @@ impl<'a,'tcx:'a> Relate<'a,'tcx> for ty::TypeAndMut<'tcx> {
                 ast::Mutability::MutImmutable => ty::Covariant,
                 ast::Mutability::MutMutable => ty::Invariant,
             };
-            let ty = try!(relation.relate_with_variance(variance, &a.ty, &b.ty));
+            let ty = relation.relate_with_variance(variance, &a.ty, &b.ty)?;
             Ok(ty::TypeAndMut {ty: ty, mutbl: mutbl})
         }
     }
@@ -152,7 +152,7 @@ pub fn relate_substs<'a,'tcx:'a,R>(relation: &mut R,
         let a_tps = a_subst.types.get_slice(space);
         let b_tps = b_subst.types.get_slice(space);
         let t_variances = variances.map(|v| v.types.get_slice(space));
-        let tps = try!(relate_type_params(relation, t_variances, a_tps, b_tps));
+        let tps = relate_type_params(relation, t_variances, a_tps, b_tps)?;
         substs.types.replace(space, tps);
     }
 
@@ -166,10 +166,10 @@ pub fn relate_substs<'a,'tcx:'a,R>(relation: &mut R,
                 let a_regions = a.get_slice(space);
                 let b_regions = b.get_slice(space);
                 let r_variances = variances.map(|v| v.regions.get_slice(space));
-                let regions = try!(relate_region_params(relation,
+                let regions = relate_region_params(relation,
                                                         r_variances,
                                                         a_regions,
-                                                        b_regions));
+                                                        b_regions)?;
                 substs.mut_regions().replace(space, regions);
             }
         }
@@ -239,9 +239,9 @@ impl<'a,'tcx:'a> Relate<'a,'tcx> for ty::BareFnTy<'tcx> {
                  -> RelateResult<'tcx, ty::BareFnTy<'tcx>>
         where R: TypeRelation<'a,'tcx>
     {
-        let unsafety = try!(relation.relate(&a.unsafety, &b.unsafety));
-        let abi = try!(relation.relate(&a.abi, &b.abi));
-        let sig = try!(relation.relate(&a.sig, &b.sig));
+        let unsafety = relation.relate(&a.unsafety, &b.unsafety)?;
+        let abi = relation.relate(&a.abi, &b.abi)?;
+        let sig = relation.relate(&a.sig, &b.sig)?;
         Ok(ty::BareFnTy {unsafety: unsafety,
                          abi: abi,
                          sig: sig})
@@ -260,19 +260,19 @@ impl<'a,'tcx:'a> Relate<'a,'tcx> for ty::FnSig<'tcx> {
                 expected_found(relation, &a.variadic, &b.variadic)));
         }
 
-        let inputs = try!(relate_arg_vecs(relation,
+        let inputs = relate_arg_vecs(relation,
                                           &a.inputs,
-                                          &b.inputs));
+                                          &b.inputs)?;
 
-        let output = try!(match (a.output, b.output) {
+        let output = match (a.output, b.output) {
             (ty::FnConverging(a_ty), ty::FnConverging(b_ty)) =>
-                Ok(ty::FnConverging(try!(relation.relate(&a_ty, &b_ty)))),
+                Ok(ty::FnConverging(relation.relate(&a_ty, &b_ty)?)),
             (ty::FnDiverging, ty::FnDiverging) =>
                 Ok(ty::FnDiverging),
             (a, b) =>
                 Err(TypeError::ConvergenceMismatch(
                     expected_found(relation, &(a != ty::FnDiverging), &(b != ty::FnDiverging)))),
-        });
+        }?;
 
         return Ok(ty::FnSig {inputs: inputs,
                              output: output,
@@ -336,7 +336,7 @@ impl<'a,'tcx:'a> Relate<'a,'tcx> for ty::ProjectionTy<'tcx> {
             Err(TypeError::ProjectionNameMismatched(
                 expected_found(relation, &a.item_name, &b.item_name)))
         } else {
-            let trait_ref = try!(relation.relate(&a.trait_ref, &b.trait_ref));
+            let trait_ref = relation.relate(&a.trait_ref, &b.trait_ref)?;
             Ok(ty::ProjectionTy { trait_ref: trait_ref, item_name: a.item_name })
         }
     }
@@ -349,8 +349,8 @@ impl<'a,'tcx:'a> Relate<'a,'tcx> for ty::ProjectionPredicate<'tcx> {
                  -> RelateResult<'tcx, ty::ProjectionPredicate<'tcx>>
         where R: TypeRelation<'a,'tcx>
     {
-        let projection_ty = try!(relation.relate(&a.projection_ty, &b.projection_ty));
-        let ty = try!(relation.relate(&a.ty, &b.ty));
+        let projection_ty = relation.relate(&a.projection_ty, &b.projection_ty)?;
+        let ty = relation.relate(&a.ty, &b.ty)?;
         Ok(ty::ProjectionPredicate { projection_ty: projection_ty, ty: ty })
     }
 }
@@ -385,13 +385,13 @@ impl<'a,'tcx:'a> Relate<'a,'tcx> for ty::ExistentialBounds<'tcx> {
         where R: TypeRelation<'a,'tcx>
     {
         let r =
-            try!(relation.with_cause(
+            relation.with_cause(
                 Cause::ExistentialRegionBound,
                 |relation| relation.relate_with_variance(ty::Contravariant,
                                                          &a.region_bound,
-                                                         &b.region_bound)));
-        let nb = try!(relation.relate(&a.builtin_bounds, &b.builtin_bounds));
-        let pb = try!(relation.relate(&a.projection_bounds, &b.projection_bounds));
+                                                         &b.region_bound))?;
+        let nb = relation.relate(&a.builtin_bounds, &b.builtin_bounds)?;
+        let pb = relation.relate(&a.projection_bounds, &b.projection_bounds)?;
         Ok(ty::ExistentialBounds { region_bound: r,
                                    builtin_bounds: nb,
                                    projection_bounds: pb })
@@ -426,7 +426,7 @@ impl<'a,'tcx:'a> Relate<'a,'tcx> for ty::TraitRef<'tcx> {
         if a.def_id != b.def_id {
             Err(TypeError::Traits(expected_found(relation, &a.def_id, &b.def_id)))
         } else {
-            let substs = try!(relate_item_substs(relation, a.def_id, a.substs, b.substs));
+            let substs = relate_item_substs(relation, a.def_id, a.substs, b.substs)?;
             Ok(ty::TraitRef { def_id: a.def_id, substs: relation.tcx().mk_substs(substs) })
         }
     }
@@ -489,21 +489,21 @@ pub fn super_relate_tys<'a,'tcx:'a,R>(relation: &mut R,
         (&ty::TyEnum(a_def, a_substs), &ty::TyEnum(b_def, b_substs))
             if a_def == b_def =>
         {
-            let substs = try!(relate_item_substs(relation, a_def.did, a_substs, b_substs));
+            let substs = relate_item_substs(relation, a_def.did, a_substs, b_substs)?;
             Ok(tcx.mk_enum(a_def, tcx.mk_substs(substs)))
         }
 
         (&ty::TyTrait(ref a_), &ty::TyTrait(ref b_)) =>
         {
-            let principal = try!(relation.relate(&a_.principal, &b_.principal));
-            let bounds = try!(relation.relate(&a_.bounds, &b_.bounds));
+            let principal = relation.relate(&a_.principal, &b_.principal)?;
+            let bounds = relation.relate(&a_.bounds, &b_.bounds)?;
             Ok(tcx.mk_trait(principal, bounds))
         }
 
         (&ty::TyStruct(a_def, a_substs), &ty::TyStruct(b_def, b_substs))
             if a_def == b_def =>
         {
-            let substs = try!(relate_item_substs(relation, a_def.did, a_substs, b_substs));
+            let substs = relate_item_substs(relation, a_def.did, a_substs, b_substs)?;
             Ok(tcx.mk_struct(a_def, tcx.mk_substs(substs)))
         }
 
@@ -514,32 +514,32 @@ pub fn super_relate_tys<'a,'tcx:'a,R>(relation: &mut R,
             // All TyClosure types with the same id represent
             // the (anonymous) type of the same closure expression. So
             // all of their regions should be equated.
-            let substs = try!(relation.relate(a_substs, b_substs));
+            let substs = relation.relate(a_substs, b_substs)?;
             Ok(tcx.mk_closure_from_closure_substs(a_id, substs))
         }
 
         (&ty::TyBox(a_inner), &ty::TyBox(b_inner)) =>
         {
-            let typ = try!(relation.relate(&a_inner, &b_inner));
+            let typ = relation.relate(&a_inner, &b_inner)?;
             Ok(tcx.mk_box(typ))
         }
 
         (&ty::TyRawPtr(ref a_mt), &ty::TyRawPtr(ref b_mt)) =>
         {
-            let mt = try!(relation.relate(a_mt, b_mt));
+            let mt = relation.relate(a_mt, b_mt)?;
             Ok(tcx.mk_ptr(mt))
         }
 
         (&ty::TyRef(a_r, ref a_mt), &ty::TyRef(b_r, ref b_mt)) =>
         {
-            let r = try!(relation.relate_with_variance(ty::Contravariant, a_r, b_r));
-            let mt = try!(relation.relate(a_mt, b_mt));
+            let r = relation.relate_with_variance(ty::Contravariant, a_r, b_r)?;
+            let mt = relation.relate(a_mt, b_mt)?;
             Ok(tcx.mk_ref(tcx.mk_region(r), mt))
         }
 
         (&ty::TyArray(a_t, sz_a), &ty::TyArray(b_t, sz_b)) =>
         {
-            let t = try!(relation.relate(&a_t, &b_t));
+            let t = relation.relate(&a_t, &b_t)?;
             if sz_a == sz_b {
                 Ok(tcx.mk_array(t, sz_a))
             } else {
@@ -549,16 +549,16 @@ pub fn super_relate_tys<'a,'tcx:'a,R>(relation: &mut R,
 
         (&ty::TySlice(a_t), &ty::TySlice(b_t)) =>
         {
-            let t = try!(relation.relate(&a_t, &b_t));
+            let t = relation.relate(&a_t, &b_t)?;
             Ok(tcx.mk_slice(t))
         }
 
         (&ty::TyTuple(ref as_), &ty::TyTuple(ref bs)) =>
         {
             if as_.len() == bs.len() {
-                let ts = try!(as_.iter().zip(bs)
+                let ts = as_.iter().zip(bs)
                                  .map(|(a, b)| relation.relate(a, b))
-                                 .collect::<Result<_, _>>());
+                                 .collect::<Result<_, _>>()?;
                 Ok(tcx.mk_tup(ts))
             } else if !(as_.is_empty() || bs.is_empty()) {
                 Err(TypeError::TupleSize(
@@ -572,20 +572,20 @@ pub fn super_relate_tys<'a,'tcx:'a,R>(relation: &mut R,
          &ty::TyFnDef(b_def_id, b_substs, b_fty))
             if a_def_id == b_def_id =>
         {
-            let substs = try!(relate_substs(relation, None, a_substs, b_substs));
-            let fty = try!(relation.relate(a_fty, b_fty));
+            let substs = relate_substs(relation, None, a_substs, b_substs)?;
+            let fty = relation.relate(a_fty, b_fty)?;
             Ok(tcx.mk_fn_def(a_def_id, tcx.mk_substs(substs), fty))
         }
 
         (&ty::TyFnPtr(a_fty), &ty::TyFnPtr(b_fty)) =>
         {
-            let fty = try!(relation.relate(a_fty, b_fty));
+            let fty = relation.relate(a_fty, b_fty)?;
             Ok(tcx.mk_fn_ptr(fty))
         }
 
         (&ty::TyProjection(ref a_data), &ty::TyProjection(ref b_data)) =>
         {
-            let projection_ty = try!(relation.relate(a_data, b_data));
+            let projection_ty = relation.relate(a_data, b_data)?;
             Ok(tcx.mk_projection(projection_ty.trait_ref, projection_ty.item_name))
         }
 
@@ -603,8 +603,8 @@ impl<'a,'tcx:'a> Relate<'a,'tcx> for ty::ClosureSubsts<'tcx> {
                  -> RelateResult<'tcx, ty::ClosureSubsts<'tcx>>
         where R: TypeRelation<'a,'tcx>
     {
-        let func_substs = try!(relate_substs(relation, None, a.func_substs, b.func_substs));
-        let upvar_tys = try!(relation.relate_zip(&a.upvar_tys, &b.upvar_tys));
+        let func_substs = relate_substs(relation, None, a.func_substs, b.func_substs)?;
+        let upvar_tys = relation.relate_zip(&a.upvar_tys, &b.upvar_tys)?;
         Ok(ty::ClosureSubsts { func_substs: relation.tcx().mk_substs(func_substs),
                                upvar_tys: upvar_tys })
     }
@@ -645,7 +645,7 @@ impl<'a,'tcx:'a,T> Relate<'a,'tcx> for Rc<T>
     {
         let a: &T = a;
         let b: &T = b;
-        Ok(Rc::new(try!(relation.relate(a, b))))
+        Ok(Rc::new(relation.relate(a, b)?))
     }
 }
 
@@ -660,7 +660,7 @@ impl<'a,'tcx:'a,T> Relate<'a,'tcx> for Box<T>
     {
         let a: &T = a;
         let b: &T = b;
-        Ok(Box::new(try!(relation.relate(a, b))))
+        Ok(Box::new(relation.relate(a, b)?))
     }
 }
 

src/librustc/middle/ty/sty.rs

@@ -250,7 +250,7 @@ pub struct ClosureSubsts<'tcx> {
 
 impl<'tcx> Decodable for &'tcx ClosureSubsts<'tcx> {
     fn decode<S: Decoder>(s: &mut S) -> Result<&'tcx ClosureSubsts<'tcx>, S::Error> {
-        let closure_substs = try! { Decodable::decode(s) };
+        let closure_substs = Decodable::decode(s)?;
         let dummy_def_id: DefId = unsafe { mem::zeroed() };
 
         cstore::tls::with_decoding_context(s, |dcx, _| {

src/librustc/mir/repr.rs

@@ -356,7 +356,7 @@ impl<'tcx> BasicBlockData<'tcx> {
 
 impl<'tcx> Debug for Terminator<'tcx> {
     fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
-        try!(self.fmt_head(fmt));
+        self.fmt_head(fmt)?;
         let successors = self.successors();
         let labels = self.fmt_successor_labels();
         assert_eq!(successors.len(), labels.len());
@@ -367,12 +367,12 @@ impl<'tcx> Debug for Terminator<'tcx> {
             1 => write!(fmt, " -> {:?}", successors[0]),
 
             _ => {
-                try!(write!(fmt, " -> ["));
+                write!(fmt, " -> [")?;
                 for (i, target) in successors.iter().enumerate() {
                     if i > 0 {
-                        try!(write!(fmt, ", "));
+                        write!(fmt, ", ")?;
                     }
-                    try!(write!(fmt, "{}: {:?}", labels[i], target));
+                    write!(fmt, "{}: {:?}", labels[i], target)?;
                 }
                 write!(fmt, "]")
             }
@@ -397,14 +397,14 @@ impl<'tcx> Terminator<'tcx> {
             Drop { ref value, .. } => write!(fmt, "drop({:?})", value),
             Call { ref func, ref args, ref destination, .. } => {
                 if let Some((ref destination, _)) = *destination {
-                    try!(write!(fmt, "{:?} = ", destination));
+                    write!(fmt, "{:?} = ", destination)?;
                 }
-                try!(write!(fmt, "{:?}(", func));
+                write!(fmt, "{:?}(", func)?;
                 for (index, arg) in args.iter().enumerate() {
                     if index > 0 {
-                        try!(write!(fmt, ", "));
+                        write!(fmt, ", ")?;
                     }
-                    try!(write!(fmt, "{:?}", arg));
+                    write!(fmt, "{:?}", arg)?;
                 }
                 write!(fmt, ")")
             }
@@ -808,11 +808,11 @@ impl<'tcx> Debug for Rvalue<'tcx> {
                     Adt(adt_def, variant, substs) => {
                         let variant_def = &adt_def.variants[variant];
 
-                        try!(ppaux::parameterized(fmt, substs, variant_def.did,
+                        ppaux::parameterized(fmt, substs, variant_def.did,
                                                   ppaux::Ns::Value, &[],
                                                   |tcx| {
                             tcx.lookup_item_type(variant_def.did).generics
-                        }));
+                        })?;
 
                         match variant_def.kind() {
                             ty::VariantKind::Unit => Ok(()),
@@ -903,7 +903,7 @@ impl<'tcx> Debug for Literal<'tcx> {
                                      |tcx| tcx.lookup_item_type(def_id).generics)
             }
             Value { ref value } => {
-                try!(write!(fmt, "const "));
+                write!(fmt, "const ")?;
                 fmt_const_val(fmt, value)
             }
         }

src/librustc/util/ppaux.rs

@@ -34,23 +34,23 @@ fn fn_sig(f: &mut fmt::Formatter,
           variadic: bool,
           output: ty::FnOutput)
           -> fmt::Result {
-    try!(write!(f, "("));
+    write!(f, "(")?;
     let mut inputs = inputs.iter();
     if let Some(&ty) = inputs.next() {
-        try!(write!(f, "{}", ty));
+        write!(f, "{}", ty)?;
         for &ty in inputs {
-            try!(write!(f, ", {}", ty));
+            write!(f, ", {}", ty)?;
         }
         if variadic {
-            try!(write!(f, ", ..."));
+            write!(f, ", ...")?;
         }
     }
-    try!(write!(f, ")"));
+    write!(f, ")")?;
 
     match output {
         ty::FnConverging(ty) => {
             if !ty.is_nil() {
-                try!(write!(f, " -> {}", ty));
+                write!(f, " -> {}", ty)?;
             }
             Ok(())
         }
@@ -77,10 +77,10 @@ pub fn parameterized<GG>(f: &mut fmt::Formatter,
     where GG: for<'tcx> FnOnce(&TyCtxt<'tcx>) -> ty::Generics<'tcx>
 {
     if let (Ns::Value, Some(self_ty)) = (ns, substs.self_ty()) {
-        try!(write!(f, "<{} as ", self_ty));
+        write!(f, "<{} as ", self_ty)?;
     }
 
-    let (fn_trait_kind, verbose, last_name) = try!(ty::tls::with(|tcx| {
+    let (fn_trait_kind, verbose, last_name) = ty::tls::with(|tcx| {
         let (did, last_name) = if ns == Ns::Value {
             // Try to get the impl/trait parent, if this is an
             // associated value item (method or constant).
@@ -89,9 +89,9 @@ pub fn parameterized<GG>(f: &mut fmt::Formatter,
         } else {
             (did, None)
         };
-        try!(write!(f, "{}", tcx.item_path_str(did)));
+        write!(f, "{}", tcx.item_path_str(did))?;
         Ok((tcx.lang_items.fn_trait_kind(did), tcx.sess.verbose(), last_name))
-    }));
+    })?;
 
     let mut empty = true;
     let mut start_or_continue = |f: &mut fmt::Formatter, start: &str, cont: &str| {
@@ -106,25 +106,25 @@ pub fn parameterized<GG>(f: &mut fmt::Formatter,
     if verbose {
         match substs.regions {
             subst::ErasedRegions => {
-                try!(start_or_continue(f, "<", ", "));
-                try!(write!(f, ".."));
+                start_or_continue(f, "<", ", ")?;
+                write!(f, "..")?;
             }
             subst::NonerasedRegions(ref regions) => {
                 for region in regions {
-                    try!(start_or_continue(f, "<", ", "));
-                    try!(write!(f, "{:?}", region));
+                    start_or_continue(f, "<", ", ")?;
+                    write!(f, "{:?}", region)?;
                 }
             }
         }
         for &ty in &substs.types {
-            try!(start_or_continue(f, "<", ", "));
-            try!(write!(f, "{}", ty));
+            start_or_continue(f, "<", ", ")?;
+            write!(f, "{}", ty)?;
         }
         for projection in projections {
-            try!(start_or_continue(f, "<", ", "));
-            try!(write!(f, "{}={}",
+            start_or_continue(f, "<", ", ")?;
+            write!(f, "{}={}",
                         projection.projection_ty.item_name,
-                        projection.ty));
+                        projection.ty)?;
         }
         return start_or_continue(f, "", ">");
     }
@@ -140,7 +140,7 @@ pub fn parameterized<GG>(f: &mut fmt::Formatter,
         subst::ErasedRegions => { }
         subst::NonerasedRegions(ref regions) => {
             for &r in regions {
-                try!(start_or_continue(f, "<", ", "));
+                start_or_continue(f, "<", ", ")?;
                 let s = r.to_string();
                 if s.is_empty() {
                     // This happens when the value of the region
@@ -148,9 +148,9 @@ pub fn parameterized<GG>(f: &mut fmt::Formatter,
                     // because the user omitted it in the first place,
                     // or because it refers to some block in the code,
                     // etc. I'm not sure how best to serialize this.
-                    try!(write!(f, "'_"));
+                    write!(f, "'_")?;
                 } else {
-                    try!(write!(f, "{}", s));
+                    write!(f, "{}", s)?;
                 }
             }
         }
@@ -194,35 +194,35 @@ pub fn parameterized<GG>(f: &mut fmt::Formatter,
     });
 
     for &ty in &tps[..tps.len() - num_defaults] {
-        try!(start_or_continue(f, "<", ", "));
-        try!(write!(f, "{}", ty));
+        start_or_continue(f, "<", ", ")?;
+        write!(f, "{}", ty)?;
     }
 
     for projection in projections {
-        try!(start_or_continue(f, "<", ", "));
-        try!(write!(f, "{}={}",
+        start_or_continue(f, "<", ", ")?;
+        write!(f, "{}={}",
                     projection.projection_ty.item_name,
-                    projection.ty));
+                    projection.ty)?;
     }
 
-    try!(start_or_continue(f, "", ">"));
+    start_or_continue(f, "", ">")?;
 
     // For values, also print their name and type parameters.
     if ns == Ns::Value {
         if substs.self_ty().is_some() {
-            try!(write!(f, ">"));
+            write!(f, ">")?;
         }
 
         if let Some(name) = last_name {
-            try!(write!(f, "::{}", name));
+            write!(f, "::{}", name)?;
         }
         let tps = substs.types.get_slice(subst::FnSpace);
         if !tps.is_empty() {
-            try!(write!(f, "::<{}", tps[0]));
+            write!(f, "::<{}", tps[0])?;
             for ty in &tps[1..] {
-                try!(write!(f, ", {}", ty));
+                write!(f, ", {}", ty)?;
             }
-            try!(write!(f, ">"));
+            write!(f, ">")?;
         }
     }
 
@@ -273,7 +273,7 @@ fn in_binder<'tcx, T, U>(f: &mut fmt::Formatter,
         })
     }).0;
 
-    try!(start_or_continue(f, "", "> "));
+    start_or_continue(f, "", "> ")?;
     write!(f, "{}", new_value)
 }
 
@@ -317,7 +317,7 @@ impl<'tcx> fmt::Display for ty::TraitTy<'tcx> {
         let bounds = &self.bounds;
 
         // Generate the main trait ref, including associated types.
-        try!(ty::tls::with(|tcx| {
+        ty::tls::with(|tcx| {
             let principal = tcx.lift(&self.principal.0)
                                .expect("could not lift TraitRef for printing");
             let projections = tcx.lift(&bounds.projection_bounds[..])
@@ -326,11 +326,11 @@ impl<'tcx> fmt::Display for ty::TraitTy<'tcx> {
 
             let tap = ty::Binder(TraitAndProjections(principal, projections));
             in_binder(f, tcx, &ty::Binder(""), Some(tap))
-        }));
+        })?;
 
         // Builtin bounds.
         for bound in &bounds.builtin_bounds {
-            try!(write!(f, " + {:?}", bound));
+            write!(f, " + {:?}", bound)?;
         }
 
         // FIXME: It'd be nice to compute from context when this bound
@@ -340,7 +340,7 @@ impl<'tcx> fmt::Display for ty::TraitTy<'tcx> {
         // people aware that it's there.
         let bound = bounds.region_bound.to_string();
         if !bound.is_empty() {
-            try!(write!(f, " + {}", bound));
+            write!(f, " + {}", bound)?;
         }
 
         Ok(())
@@ -648,19 +648,19 @@ impl<'tcx> fmt::Debug for ty::InstantiatedPredicates<'tcx> {
 
 impl<'tcx> fmt::Debug for ty::ImplOrTraitItem<'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(f, "ImplOrTraitItem("));
-        try!(match *self {
+        write!(f, "ImplOrTraitItem(")?;
+        match *self {
             ty::ImplOrTraitItem::MethodTraitItem(ref i) => write!(f, "{:?}", i),
             ty::ImplOrTraitItem::ConstTraitItem(ref i) => write!(f, "{:?}", i),
             ty::ImplOrTraitItem::TypeTraitItem(ref i) => write!(f, "{:?}", i),
-        });
+        }?;
         write!(f, ")")
     }
 }
 
 impl<'tcx> fmt::Display for ty::FnSig<'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(f, "fn"));
+        write!(f, "fn")?;
         fn_sig(f, &self.inputs, self.variadic, self.output)
     }
 }
@@ -679,18 +679,18 @@ impl<'tcx> fmt::Debug for ty::ExistentialBounds<'tcx> {
 
         let region_str = format!("{:?}", self.region_bound);
         if !region_str.is_empty() {
-            try!(maybe_continue(f));
-            try!(write!(f, "{}", region_str));
+            maybe_continue(f)?;
+            write!(f, "{}", region_str)?;
         }
 
         for bound in &self.builtin_bounds {
-            try!(maybe_continue(f));
-            try!(write!(f, "{:?}", bound));
+            maybe_continue(f)?;
+            write!(f, "{:?}", bound)?;
         }
 
         for projection_bound in &self.projection_bounds {
-            try!(maybe_continue(f));
-            try!(write!(f, "{:?}", projection_bound));
+            maybe_continue(f)?;
+            write!(f, "{:?}", projection_bound)?;
         }
 
         Ok(())
@@ -701,9 +701,9 @@ impl fmt::Display for ty::BuiltinBounds {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let mut bounds = self.iter();
         if let Some(bound) = bounds.next() {
-            try!(write!(f, "{:?}", bound));
+            write!(f, "{:?}", bound)?;
             for bound in bounds {
-                try!(write!(f, " + {:?}", bound));
+                write!(f, " + {:?}", bound)?;
             }
         }
         Ok(())
@@ -832,23 +832,23 @@ impl<'tcx> fmt::Display for ty::TypeVariants<'tcx> {
                 },  tm.ty)
             }
             TyRef(r, ref tm) => {
-                try!(write!(f, "&"));
+                write!(f, "&")?;
                 let s = r.to_string();
-                try!(write!(f, "{}", s));
+                write!(f, "{}", s)?;
                 if !s.is_empty() {
-                    try!(write!(f, " "));
+                    write!(f, " ")?;
                 }
                 write!(f, "{}", tm)
             }
             TyTuple(ref tys) => {
-                try!(write!(f, "("));
+                write!(f, "(")?;
                 let mut tys = tys.iter();
                 if let Some(&ty) = tys.next() {
-                    try!(write!(f, "{},", ty));
+                    write!(f, "{},", ty)?;
                     if let Some(&ty) = tys.next() {
-                        try!(write!(f, " {}", ty));
+                        write!(f, " {}", ty)?;
                         for &ty in tys {
-                            try!(write!(f, ", {}", ty));
+                            write!(f, ", {}", ty)?;
                         }
                     }
                 }
@@ -856,25 +856,25 @@ impl<'tcx> fmt::Display for ty::TypeVariants<'tcx> {
             }
             TyFnDef(def_id, substs, ref bare_fn) => {
                 if bare_fn.unsafety == hir::Unsafety::Unsafe {
-                    try!(write!(f, "unsafe "));
+                    write!(f, "unsafe ")?;
                 }
 
                 if bare_fn.abi != Abi::Rust {
-                    try!(write!(f, "extern {} ", bare_fn.abi));
+                    write!(f, "extern {} ", bare_fn.abi)?;
                 }
 
-                try!(write!(f, "{} {{", bare_fn.sig.0));
-                try!(parameterized(f, substs, def_id, Ns::Value, &[],
-                                   |tcx| tcx.lookup_item_type(def_id).generics));
+                write!(f, "{} {{", bare_fn.sig.0)?;
+                parameterized(f, substs, def_id, Ns::Value, &[],
+                                   |tcx| tcx.lookup_item_type(def_id).generics)?;
                 write!(f, "}}")
             }
             TyFnPtr(ref bare_fn) => {
                 if bare_fn.unsafety == hir::Unsafety::Unsafe {
-                    try!(write!(f, "unsafe "));
+                    write!(f, "unsafe ")?;
                 }
 
                 if bare_fn.abi != Abi::Rust {
-                    try!(write!(f, "extern {} ", bare_fn.abi));
+                    write!(f, "extern {} ", bare_fn.abi)?;
                 }
 
                 write!(f, "{}", bare_fn.sig.0)
@@ -897,30 +897,30 @@ impl<'tcx> fmt::Display for ty::TypeVariants<'tcx> {
             ty::TyProjection(ref data) => write!(f, "{}", data),
             TyStr => write!(f, "str"),
             TyClosure(did, ref substs) => ty::tls::with(|tcx| {
-                try!(write!(f, "[closure"));
+                write!(f, "[closure")?;
 
                 if let Some(node_id) = tcx.map.as_local_node_id(did) {
-                    try!(write!(f, "@{:?}", tcx.map.span(node_id)));
+                    write!(f, "@{:?}", tcx.map.span(node_id))?;
                     let mut sep = " ";
-                    try!(tcx.with_freevars(node_id, |freevars| {
+                    tcx.with_freevars(node_id, |freevars| {
                         for (freevar, upvar_ty) in freevars.iter().zip(&substs.upvar_tys) {
                             let node_id = freevar.def.var_id();
-                            try!(write!(f,
+                            write!(f,
                                         "{}{}:{}",
                                         sep,
                                         tcx.local_var_name_str(node_id),
-                                        upvar_ty));
+                                        upvar_ty)?;
                             sep = ", ";
                         }
                         Ok(())
-                    }))
+                    })?
                 } else {
                     // cross-crate closure types should only be
                     // visible in trans bug reports, I imagine.
-                    try!(write!(f, "@{:?}", did));
+                    write!(f, "@{:?}", did)?;
                     let mut sep = " ";
                     for (index, upvar_ty) in substs.upvar_tys.iter().enumerate() {
-                        try!(write!(f, "{}{}:{}", sep, index, upvar_ty));
+                        write!(f, "{}{}:{}", sep, index, upvar_ty)?;
                         sep = ", ";
                     }
                 }

src/librustc_back/target/mod.rs

@@ -464,11 +464,11 @@ impl Target {
         use serialize::json;
 
         fn load_file(path: &Path) -> Result<Target, String> {
-            let mut f = try!(File::open(path).map_err(|e| e.to_string()));
+            let mut f = File::open(path).map_err(|e| e.to_string())?;
             let mut contents = Vec::new();
-            try!(f.read_to_end(&mut contents).map_err(|e| e.to_string()));
-            let obj = try!(json::from_reader(&mut &contents[..])
-                                .map_err(|e| e.to_string()));
+            f.read_to_end(&mut contents).map_err(|e| e.to_string())?;
+            let obj = json::from_reader(&mut &contents[..])
+                                .map_err(|e| e.to_string())?;
             Ok(Target::from_json(obj))
         }
 

src/librustc_back/tempdir.rs

@@ -45,7 +45,7 @@ impl TempDir {
         let storage;
         let mut tmpdir = tmpdir;
         if !tmpdir.is_absolute() {
-            let cur_dir = try!(env::current_dir());
+            let cur_dir = env::current_dir()?;
             storage = cur_dir.join(tmpdir);
             tmpdir = &storage;
             // return TempDir::new_in(&cur_dir.join(tmpdir), prefix);

src/librustc_borrowck/borrowck/mir/gather_moves.rs

@@ -112,15 +112,15 @@ impl<'tcx> PreMovePath<'tcx> {
 
 impl<'tcx> fmt::Debug for MovePath<'tcx> {
     fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(w, "MovePath {{"));
+        write!(w, "MovePath {{")?;
         if let Some(parent) = self.parent {
-            try!(write!(w, " parent: {:?},", parent));
+            write!(w, " parent: {:?},", parent)?;
         }
         if let Some(first_child) = self.first_child {
-            try!(write!(w, " first_child: {:?},", first_child));
+            write!(w, " first_child: {:?},", first_child)?;
         }
         if let Some(next_sibling) = self.next_sibling {
-            try!(write!(w, " next_sibling: {:?}", next_sibling));
+            write!(w, " next_sibling: {:?}", next_sibling)?;
         }
         write!(w, " content: {:?} }}", self.content)
     }

src/librustc_borrowck/borrowck/mir/graphviz.rs

@@ -31,7 +31,7 @@ pub fn print_borrowck_graph_to(mbcx: &MirBorrowckCtxt,
                                path: &str) -> io::Result<()> {
     let g = Graph { mbcx: mbcx, context: context };
     let mut v = Vec::new();
-    try!(dot::render(&g, &mut v));
+    dot::render(&g, &mut v)?;
     println!("print_borrowck_graph_to path: {} context: {} node_id: {}",
              path, context, mbcx.node_id);
     File::create(path).and_then(|mut f| f.write_all(&v))
@@ -121,18 +121,18 @@ impl<'c, 'b:'c, 'a:'b, 'tcx:'a> dot::Labeller<'c> for Graph<'c,'b,'a,'tcx> {
             for c in interpreted.chunks(chunk_size) {
                 if seen_one {
                     // if not the first row, finish off the previous row
-                    try!(write!(w, "</td><td></td><td></td></tr>"));
+                    write!(w, "</td><td></td><td></td></tr>")?;
                 }
-                try!(write!(w, "<tr><td></td><td {bg} {align}>{objs:?}",
+                write!(w, "<tr><td></td><td {bg} {align}>{objs:?}",
                             bg = BG_FLOWCONTENT,
                             align = ALIGN_RIGHT,
-                            objs = c));
+                            objs = c)?;
                 seen_one = true;
             }
             if !seen_one {
-                try!(write!(w, "<tr><td></td><td {bg} {align}>[]",
+                write!(w, "<tr><td></td><td {bg} {align}>[]",
                             bg = BG_FLOWCONTENT,
-                            align = ALIGN_RIGHT));
+                            align = ALIGN_RIGHT)?;
             }
             Ok(())
         }
@@ -141,7 +141,7 @@ impl<'c, 'b:'c, 'a:'b, 'tcx:'a> dot::Labeller<'c> for Graph<'c,'b,'a,'tcx> {
             |w| {
                 let flow = &self.mbcx.flow_state;
                 let entry = flow.interpret_set(flow.sets.on_entry_set_for(i));
-                try!(chunked_present_left(w, &entry[..], chunk_size));
+                chunked_present_left(w, &entry[..], chunk_size)?;
                 write!(w, "= ENTRY:</td><td {bg}><FONT {face}>{entrybits:?}</FONT></td>\
                                         <td></td></tr>",
                        bg = BG_FLOWCONTENT,
@@ -153,40 +153,40 @@ impl<'c, 'b:'c, 'a:'b, 'tcx:'a> dot::Labeller<'c> for Graph<'c,'b,'a,'tcx> {
                 let flow = &self.mbcx.flow_state;
                 let gen = flow.interpret_set( flow.sets.gen_set_for(i));
                 let kill = flow.interpret_set(flow.sets.kill_set_for(i));
-                try!(chunked_present_left(w, &gen[..], chunk_size));
-                try!(write!(w, " = GEN:</td><td {bg}><FONT {face}>{genbits:?}</FONT></td>\
+                chunked_present_left(w, &gen[..], chunk_size)?;
+                write!(w, " = GEN:</td><td {bg}><FONT {face}>{genbits:?}</FONT></td>\
                                             <td></td></tr>",
                             bg = BG_FLOWCONTENT,
                             face = FACE_MONOSPACE,
                             genbits=bits_to_string( flow.sets.gen_set_for(i),
-                                                    flow.sets.bytes_per_block())));
-                try!(write!(w, "<tr><td></td><td {bg} {align}>KILL:</td>\
+                                                    flow.sets.bytes_per_block()))?;
+                write!(w, "<tr><td></td><td {bg} {align}>KILL:</td>\
                                              <td {bg}><FONT {face}>{killbits:?}</FONT></td>",
                             bg = BG_FLOWCONTENT,
                             align = ALIGN_RIGHT,
                             face = FACE_MONOSPACE,
                             killbits=bits_to_string(flow.sets.kill_set_for(i),
-                                                    flow.sets.bytes_per_block())));
+                                                    flow.sets.bytes_per_block()))?;
 
                 // (chunked_present_right)
                 let mut seen_one = false;
                 for k in kill.chunks(chunk_size) {
                     if !seen_one {
                         // continuation of row; this is fourth <td>
-                        try!(write!(w, "<td {bg}>= {kill:?}</td></tr>",
+                        write!(w, "<td {bg}>= {kill:?}</td></tr>",
                                     bg = BG_FLOWCONTENT,
-                                    kill=k));
+                                    kill=k)?;
                     } else {
                         // new row, with indent of three <td>'s
-                        try!(write!(w, "<tr><td></td><td></td><td></td><td {bg}>{kill:?}</td></tr>",
+                        write!(w, "<tr><td></td><td></td><td></td><td {bg}>{kill:?}</td></tr>",
                                     bg = BG_FLOWCONTENT,
-                                    kill=k));
+                                    kill=k)?;
                     }
                     seen_one = true;
                 }
                 if !seen_one {
-                    try!(write!(w, "<td {bg}>= []</td></tr>",
-                                bg = BG_FLOWCONTENT));
+                    write!(w, "<td {bg}>= []</td></tr>",
+                                bg = BG_FLOWCONTENT)?;
                 }
 
                 Ok(())

src/librustc_const_eval/int.rs

@@ -220,7 +220,7 @@ impl ConstInt {
 
     /// Compares the values if they are of the same type
     pub fn try_cmp(self, rhs: Self) -> Result<::std::cmp::Ordering, ConstMathErr> {
-        match try!(self.infer(rhs)) {
+        match self.infer(rhs)? {
             (I8(a), I8(b)) => Ok(a.cmp(&b)),
             (I16(a), I16(b)) => Ok(a.cmp(&b)),
             (I32(a), I32(b)) => Ok(a.cmp(&b)),
@@ -420,8 +420,8 @@ fn check_division(
 impl ::std::ops::Div for ConstInt {
     type Output = Result<Self, ConstMathErr>;
     fn div(self, rhs: Self) -> Result<Self, ConstMathErr> {
-        let (lhs, rhs) = try!(self.infer(rhs));
-        try!(check_division(lhs, rhs, Op::Div, DivisionByZero));
+        let (lhs, rhs) = self.infer(rhs)?;
+        check_division(lhs, rhs, Op::Div, DivisionByZero)?;
         match (lhs, rhs) {
             (I8(a), I8(b)) => Ok(I8(a/b)),
             (I16(a), I16(b)) => Ok(I16(a/b)),
@@ -447,9 +447,9 @@ impl ::std::ops::Div for ConstInt {
 impl ::std::ops::Rem for ConstInt {
     type Output = Result<Self, ConstMathErr>;
     fn rem(self, rhs: Self) -> Result<Self, ConstMathErr> {
-        let (lhs, rhs) = try!(self.infer(rhs));
+        let (lhs, rhs) = self.infer(rhs)?;
         // should INT_MIN%-1 be zero or an error?
-        try!(check_division(lhs, rhs, Op::Rem, RemainderByZero));
+        check_division(lhs, rhs, Op::Rem, RemainderByZero)?;
         match (lhs, rhs) {
             (I8(a), I8(b)) => Ok(I8(a%b)),
             (I16(a), I16(b)) => Ok(I16(a%b)),
@@ -475,7 +475,7 @@ impl ::std::ops::Rem for ConstInt {
 impl ::std::ops::Shl<ConstInt> for ConstInt {
     type Output = Result<Self, ConstMathErr>;
     fn shl(self, rhs: Self) -> Result<Self, ConstMathErr> {
-        let b = try!(rhs.to_u32().ok_or(ShiftNegative));
+        let b = rhs.to_u32().ok_or(ShiftNegative)?;
         match self {
             I8(a) => Ok(I8(overflowing!(a.overflowing_shl(b), Op::Shl))),
             I16(a) => Ok(I16(overflowing!(a.overflowing_shl(b), Op::Shl))),
@@ -498,7 +498,7 @@ impl ::std::ops::Shl<ConstInt> for ConstInt {
 impl ::std::ops::Shr<ConstInt> for ConstInt {
     type Output = Result<Self, ConstMathErr>;
     fn shr(self, rhs: Self) -> Result<Self, ConstMathErr> {
-        let b = try!(rhs.to_u32().ok_or(ShiftNegative));
+        let b = rhs.to_u32().ok_or(ShiftNegative)?;
         match self {
             I8(a) => Ok(I8(overflowing!(a.overflowing_shr(b), Op::Shr))),
             I16(a) => Ok(I16(overflowing!(a.overflowing_shr(b), Op::Shr))),

src/librustc_driver/driver.rs

@@ -99,11 +99,11 @@ pub fn compile_input(sess: &Session,
 
             let outputs = build_output_filenames(input, outdir, output, &krate.attrs, sess);
             let id = link::find_crate_name(Some(sess), &krate.attrs, input);
-            let expanded_crate = try!(phase_2_configure_and_expand(sess,
+            let expanded_crate = phase_2_configure_and_expand(sess,
                                                                    &cstore,
                                                                    krate,
                                                                    &id[..],
-                                                                   addl_plugins));
+                                                                   addl_plugins)?;
 
             (outputs, expanded_crate, id)
         };
@@ -168,7 +168,7 @@ pub fn compile_input(sess: &Session,
             None
         };
 
-        try!(try!(phase_3_run_analysis_passes(sess,
+        phase_3_run_analysis_passes(sess,
                                               &cstore,
                                               hir_map,
                                               &arenas,
@@ -196,7 +196,7 @@ pub fn compile_input(sess: &Session,
                 }
             }
 
-            try!(result);
+            result?;
 
             if log_enabled!(::log::INFO) {
                 println!("Pre-trans");
@@ -215,7 +215,7 @@ pub fn compile_input(sess: &Session,
             token::get_ident_interner().clear();
 
             Ok((outputs, trans))
-        })))
+        })??
     };
 
     let phase5_result = phase_5_run_llvm_passes(sess, &trans, &outputs);
@@ -224,7 +224,7 @@ pub fn compile_input(sess: &Session,
                             sess,
                             CompileState::state_after_llvm(input, sess, outdir, &trans),
                             phase5_result);
-    try!(phase5_result);
+    phase5_result?;
 
     phase_6_link_output(sess, &trans, &outputs);
 
@@ -428,7 +428,7 @@ pub fn phase_1_parse_input<'a>(sess: &'a Session,
     syntax::ext::mtwt::reset_tables();
     token::reset_ident_interner();
 
-    let krate = try!(time(sess.time_passes(), "parsing", || {
+    let krate = time(sess.time_passes(), "parsing", || {
         match *input {
             Input::File(ref file) => {
                 parse::parse_crate_from_file(file, cfg.clone(), &sess.parse_sess)
@@ -440,7 +440,7 @@ pub fn phase_1_parse_input<'a>(sess: &'a Session,
                                                    &sess.parse_sess)
             }
         }
-    }));
+    })?;
 
     if sess.opts.debugging_opts.ast_json_noexpand {
         println!("{}", json::as_json(&krate));
@@ -491,13 +491,13 @@ pub fn phase_2_configure_and_expand(sess: &Session,
     // baz! should not use this definition unless foo is enabled.
 
     let mut feature_gated_cfgs = vec![];
-    krate = try!(time(time_passes, "configuration 1", || {
+    krate = time(time_passes, "configuration 1", || {
         sess.track_errors(|| {
             syntax::config::strip_unconfigured_items(sess.diagnostic(),
                                                      krate,
                                                      &mut feature_gated_cfgs)
         })
-    }));
+    })?;
 
     *sess.crate_types.borrow_mut() = collect_crate_types(sess, &krate.attrs);
     *sess.crate_metadata.borrow_mut() = collect_crate_metadata(sess, &krate.attrs);
@@ -506,7 +506,7 @@ pub fn phase_2_configure_and_expand(sess: &Session,
         middle::recursion_limit::update_recursion_limit(sess, &krate);
     });
 
-    try!(time(time_passes, "gated macro checking", || {
+    time(time_passes, "gated macro checking", || {
         sess.track_errors(|| {
             let features =
               syntax::feature_gate::check_crate_macros(sess.codemap(),
@@ -516,7 +516,7 @@ pub fn phase_2_configure_and_expand(sess: &Session,
             // these need to be set "early" so that expansion sees `quote` if enabled.
             *sess.features.borrow_mut() = features;
         })
-    }));
+    })?;
 
 
     krate = time(time_passes, "crate injection", || {
@@ -553,7 +553,7 @@ pub fn phase_2_configure_and_expand(sess: &Session,
     let Registry { syntax_exts, early_lint_passes, late_lint_passes, lint_groups,
                    llvm_passes, attributes, mir_passes, .. } = registry;
 
-    try!(sess.track_errors(|| {
+    sess.track_errors(|| {
         let mut ls = sess.lint_store.borrow_mut();
         for pass in early_lint_passes {
             ls.register_early_pass(Some(sess), true, pass);
@@ -569,14 +569,14 @@ pub fn phase_2_configure_and_expand(sess: &Session,
         *sess.plugin_llvm_passes.borrow_mut() = llvm_passes;
         sess.mir_passes.borrow_mut().extend(mir_passes);
         *sess.plugin_attributes.borrow_mut() = attributes.clone();
-    }));
+    })?;
 
     // Lint plugins are registered; now we can process command line flags.
     if sess.opts.describe_lints {
         super::describe_lints(&sess.lint_store.borrow(), true);
         return Err(0);
     }
-    try!(sess.track_errors(|| sess.lint_store.borrow_mut().process_command_line(sess)));
+    sess.track_errors(|| sess.lint_store.borrow_mut().process_command_line(sess))?;
 
     krate = time(time_passes, "expansion", || {
         // Windows dlls do not have rpaths, so they don't know how to find their
@@ -619,7 +619,7 @@ pub fn phase_2_configure_and_expand(sess: &Session,
     // of macro expansion.  This runs before #[cfg] to try to catch as
     // much as possible (e.g. help the programmer avoid platform
     // specific differences)
-    try!(time(time_passes, "complete gated feature checking 1", || {
+    time(time_passes, "complete gated feature checking 1", || {
         sess.track_errors(|| {
             let features = syntax::feature_gate::check_crate(sess.codemap(),
                                                              &sess.parse_sess.span_diagnostic,
@@ -628,12 +628,12 @@ pub fn phase_2_configure_and_expand(sess: &Session,
                                                              sess.opts.unstable_features);
             *sess.features.borrow_mut() = features;
         })
-    }));
+    })?;
 
     // JBC: make CFG processing part of expansion to avoid this problem:
 
     // strip again, in case expansion added anything with a #[cfg].
-    krate = try!(sess.track_errors(|| {
+    krate = sess.track_errors(|| {
         let krate = time(time_passes, "configuration 2", || {
             syntax::config::strip_unconfigured_items(sess.diagnostic(),
                                                      krate,
@@ -650,7 +650,7 @@ pub fn phase_2_configure_and_expand(sess: &Session,
         });
 
         krate
-    }));
+    })?;
 
     krate = time(time_passes, "maybe building test harness", || {
         syntax::test::modify_for_testing(&sess.parse_sess, &sess.opts.cfg, krate, sess.diagnostic())
@@ -671,7 +671,7 @@ pub fn phase_2_configure_and_expand(sess: &Session,
     // One final feature gating of the true AST that gets compiled
     // later, to make sure we've got everything (e.g. configuration
     // can insert new attributes via `cfg_attr`)
-    try!(time(time_passes, "complete gated feature checking 2", || {
+    time(time_passes, "complete gated feature checking 2", || {
         sess.track_errors(|| {
             let features = syntax::feature_gate::check_crate(sess.codemap(),
                                                              &sess.parse_sess.span_diagnostic,
@@ -680,11 +680,11 @@ pub fn phase_2_configure_and_expand(sess: &Session,
                                                              sess.opts.unstable_features);
             *sess.features.borrow_mut() = features;
         })
-    }));
+    })?;
 
-    try!(time(time_passes,
+    time(time_passes,
               "const fn bodies and arguments",
-              || const_fn::check_crate(sess, &krate)));
+              || const_fn::check_crate(sess, &krate))?;
 
     if sess.opts.debugging_opts.input_stats {
         println!("Post-expansion node count: {}", count_nodes(&krate));
@@ -756,11 +756,11 @@ pub fn phase_3_run_analysis_passes<'tcx, F, R>(sess: &'tcx Session,
          "external crate/lib resolution",
          || LocalCrateReader::new(sess, cstore, &hir_map).read_crates());
 
-    let lang_items = try!(time(time_passes, "language item collection", || {
+    let lang_items = time(time_passes, "language item collection", || {
         sess.track_errors(|| {
             middle::lang_items::collect_language_items(&sess, &hir_map)
         })
-    }));
+    })?;
 
     let resolve::CrateMap {
         def_map,
@@ -780,11 +780,11 @@ pub fn phase_3_run_analysis_passes<'tcx, F, R>(sess: &'tcx Session,
         glob_map: glob_map,
     };
 
-    let named_region_map = try!(time(time_passes,
+    let named_region_map = time(time_passes,
                                      "lifetime resolution",
                                      || middle::resolve_lifetime::krate(sess,
                                                                         &hir_map,
-                                                                        &def_map.borrow())));
+                                                                        &def_map.borrow()))?;
 
     time(time_passes,
          "looking for entry point",
@@ -802,9 +802,9 @@ pub fn phase_3_run_analysis_passes<'tcx, F, R>(sess: &'tcx Session,
          "loop checking",
          || loops::check_crate(sess, &hir_map));
 
-    try!(time(time_passes,
+    time(time_passes,
               "static item recursion checking",
-              || static_recursion::check_crate(sess, &def_map.borrow(), &hir_map)));
+              || static_recursion::check_crate(sess, &def_map.borrow(), &hir_map))?;
 
     let index = stability::Index::new(&hir_map);
 
@@ -1023,16 +1023,16 @@ fn write_out_deps(sess: &Session, outputs: &OutputFilenames, id: &str) {
                                          .filter(|fmap| !fmap.is_imported())
                                          .map(|fmap| escape_dep_filename(&fmap.name))
                                          .collect();
-            let mut file = try!(fs::File::create(&deps_filename));
+            let mut file = fs::File::create(&deps_filename)?;
             for path in &out_filenames {
-                try!(write!(file, "{}: {}\n\n", path.display(), files.join(" ")));
+                write!(file, "{}: {}\n\n", path.display(), files.join(" "))?;
             }
 
             // Emit a fake target for each input file to the compilation. This
             // prevents `make` from spitting out an error if a file is later
             // deleted. For more info see #28735
             for path in files {
-                try!(writeln!(file, "{}:", path));
+                writeln!(file, "{}:", path)?;
             }
             Ok(())
         })();

src/librustc_driver/pretty.rs

@@ -325,24 +325,24 @@ impl<'ast> pprust::PpAnn for IdentifiedAnnotation<'ast> {
             pprust::NodeIdent(_) | pprust::NodeName(_) => Ok(()),
 
             pprust::NodeItem(item) => {
-                try!(pp::space(&mut s.s));
+                pp::space(&mut s.s)?;
                 s.synth_comment(item.id.to_string())
             }
             pprust::NodeSubItem(id) => {
-                try!(pp::space(&mut s.s));
+                pp::space(&mut s.s)?;
                 s.synth_comment(id.to_string())
             }
             pprust::NodeBlock(blk) => {
-                try!(pp::space(&mut s.s));
+                pp::space(&mut s.s)?;
                 s.synth_comment(format!("block {}", blk.id))
             }
             pprust::NodeExpr(expr) => {
-                try!(pp::space(&mut s.s));
-                try!(s.synth_comment(expr.id.to_string()));
+                pp::space(&mut s.s)?;
+                s.synth_comment(expr.id.to_string())?;
                 s.pclose()
             }
             pprust::NodePat(pat) => {
-                try!(pp::space(&mut s.s));
+                pp::space(&mut s.s)?;
                 s.synth_comment(format!("pat {}", pat.id))
             }
         }
@@ -374,24 +374,24 @@ impl<'ast> pprust_hir::PpAnn for IdentifiedAnnotation<'ast> {
         match node {
             pprust_hir::NodeName(_) => Ok(()),
             pprust_hir::NodeItem(item) => {
-                try!(pp::space(&mut s.s));
+                pp::space(&mut s.s)?;
                 s.synth_comment(item.id.to_string())
             }
             pprust_hir::NodeSubItem(id) => {
-                try!(pp::space(&mut s.s));
+                pp::space(&mut s.s)?;
                 s.synth_comment(id.to_string())
             }
             pprust_hir::NodeBlock(blk) => {
-                try!(pp::space(&mut s.s));
+                pp::space(&mut s.s)?;
                 s.synth_comment(format!("block {}", blk.id))
             }
             pprust_hir::NodeExpr(expr) => {
-                try!(pp::space(&mut s.s));
-                try!(s.synth_comment(expr.id.to_string()));
+                pp::space(&mut s.s)?;
+                s.synth_comment(expr.id.to_string())?;
                 s.pclose()
             }
             pprust_hir::NodePat(pat) => {
-                try!(pp::space(&mut s.s));
+                pp::space(&mut s.s)?;
                 s.synth_comment(format!("pat {}", pat.id))
             }
         }
@@ -421,13 +421,13 @@ impl<'ast> pprust::PpAnn for HygieneAnnotation<'ast> {
     fn post(&self, s: &mut pprust::State, node: pprust::AnnNode) -> io::Result<()> {
         match node {
             pprust::NodeIdent(&ast::Ident { name: ast::Name(nm), ctxt }) => {
-                try!(pp::space(&mut s.s));
+                pp::space(&mut s.s)?;
                 // FIXME #16420: this doesn't display the connections
                 // between syntax contexts
                 s.synth_comment(format!("{}#{}", nm, ctxt.0))
             }
             pprust::NodeName(&ast::Name(nm)) => {
-                try!(pp::space(&mut s.s));
+                pp::space(&mut s.s)?;
                 s.synth_comment(nm.to_string())
             }
             _ => Ok(()),
@@ -464,10 +464,10 @@ impl<'a, 'tcx> pprust_hir::PpAnn for TypedAnnotation<'a, 'tcx> {
     fn post(&self, s: &mut pprust_hir::State, node: pprust_hir::AnnNode) -> io::Result<()> {
         match node {
             pprust_hir::NodeExpr(expr) => {
-                try!(pp::space(&mut s.s));
-                try!(pp::word(&mut s.s, "as"));
-                try!(pp::space(&mut s.s));
-                try!(pp::word(&mut s.s, &self.tcx.expr_ty(expr).to_string()));
+                pp::space(&mut s.s)?;
+                pp::word(&mut s.s, "as")?;
+                pp::space(&mut s.s)?;
+                pp::word(&mut s.s, &self.tcx.expr_ty(expr).to_string())?;
                 s.pclose()
             }
             _ => Ok(()),
@@ -806,10 +806,10 @@ pub fn pretty_print_input(sess: Session,
                                                       Some(ast_map.krate()));
                 for node_id in uii.all_matching_node_ids(ast_map) {
                     let node = ast_map.get(node_id);
-                    try!(pp_state.print_node(&node));
-                    try!(pp::space(&mut pp_state.s));
-                    try!(pp_state.synth_comment(ast_map.path_to_string(node_id)));
-                    try!(pp::hardbreak(&mut pp_state.s));
+                    pp_state.print_node(&node)?;
+                    pp::space(&mut pp_state.s)?;
+                    pp_state.synth_comment(ast_map.path_to_string(node_id))?;
+                    pp::hardbreak(&mut pp_state.s)?;
                 }
                 pp::eof(&mut pp_state.s)
             })
@@ -836,15 +836,15 @@ pub fn pretty_print_input(sess: Session,
                         let mir = mir_map.map.get(&nodeid).unwrap_or_else(|| {
                             sess.fatal(&format!("no MIR map entry for node {}", nodeid))
                         });
-                        try!(match pp_type {
+                        match pp_type {
                             PpmMir => write_mir_pretty(tcx, iter::once((&nodeid, mir)), &mut out),
                             _ => write_mir_graphviz(tcx, iter::once((&nodeid, mir)), &mut out)
-                        });
+                        }?;
                     } else {
-                        try!(match pp_type {
+                        match pp_type {
                             PpmMir => write_mir_pretty(tcx, mir_map.map.iter(), &mut out),
                             _ => write_mir_graphviz(tcx, mir_map.map.iter(), &mut out)
-                        });
+                        }?;
                     }
                 }
                 Ok(())

src/librustc_front/hir.rs

@@ -119,7 +119,7 @@ impl Encodable for Ident {
 
 impl Decodable for Ident {
     fn decode<D: Decoder>(d: &mut D) -> Result<Ident, D::Error> {
-        Ok(Ident::from_name(try!(Name::decode(d))))
+        Ok(Ident::from_name(Name::decode(d)?))
     }
 }
 

src/librustc_metadata/decoder.rs

@@ -1221,11 +1221,11 @@ fn get_attributes(md: rbml::Doc) -> Vec<ast::Attribute> {
 
 fn list_crate_attributes(md: rbml::Doc, hash: &Svh,
                          out: &mut io::Write) -> io::Result<()> {
-    try!(write!(out, "=Crate Attributes ({})=\n", *hash));
+    write!(out, "=Crate Attributes ({})=\n", *hash)?;
 
     let r = get_attributes(md);
     for attr in &r {
-        try!(write!(out, "{}\n", pprust::attribute_to_string(attr)));
+        write!(out, "{}\n", pprust::attribute_to_string(attr))?;
     }
 
     write!(out, "\n\n")
@@ -1267,11 +1267,11 @@ pub fn get_crate_deps(data: &[u8]) -> Vec<CrateDep> {
 }
 
 fn list_crate_deps(data: &[u8], out: &mut io::Write) -> io::Result<()> {
-    try!(write!(out, "=External Dependencies=\n"));
+    write!(out, "=External Dependencies=\n")?;
     for dep in &get_crate_deps(data) {
-        try!(write!(out, "{} {}-{}\n", dep.cnum, dep.name, dep.hash));
+        write!(out, "{} {}-{}\n", dep.cnum, dep.name, dep.hash)?;
     }
-    try!(write!(out, "\n"));
+    write!(out, "\n")?;
     Ok(())
 }
 
@@ -1308,7 +1308,7 @@ pub fn get_crate_name(data: &[u8]) -> String {
 pub fn list_crate_metadata(bytes: &[u8], out: &mut io::Write) -> io::Result<()> {
     let hash = get_crate_hash(bytes);
     let md = rbml::Doc::new(bytes);
-    try!(list_crate_attributes(md, &hash, out));
+    list_crate_attributes(md, &hash, out)?;
     list_crate_deps(bytes, out)
 }
 

src/librustc_mir/graphviz.rs

@@ -19,26 +19,26 @@ use syntax::ast::NodeId;
 pub fn write_mir_graphviz<'a, 't, W, I>(tcx: &ty::TyCtxt<'t>, iter: I, w: &mut W) -> io::Result<()>
 where W: Write, I: Iterator<Item=(&'a NodeId, &'a Mir<'a>)> {
     for (&nodeid, mir) in iter {
-        try!(writeln!(w, "digraph Mir_{} {{", nodeid));
+        writeln!(w, "digraph Mir_{} {{", nodeid)?;
 
         // Global graph properties
-        try!(writeln!(w, r#"    graph [fontname="monospace"];"#));
-        try!(writeln!(w, r#"    node [fontname="monospace"];"#));
-        try!(writeln!(w, r#"    edge [fontname="monospace"];"#));
+        writeln!(w, r#"    graph [fontname="monospace"];"#)?;
+        writeln!(w, r#"    node [fontname="monospace"];"#)?;
+        writeln!(w, r#"    edge [fontname="monospace"];"#)?;
 
         // Graph label
-        try!(write_graph_label(tcx, nodeid, mir, w));
+        write_graph_label(tcx, nodeid, mir, w)?;
 
         // Nodes
         for block in mir.all_basic_blocks() {
-            try!(write_node(block, mir, w));
+            write_node(block, mir, w)?;
         }
 
         // Edges
         for source in mir.all_basic_blocks() {
-            try!(write_edges(source, mir, w));
+            write_edges(source, mir, w)?;
         }
-        try!(writeln!(w, "}}"))
+        writeln!(w, "}}")?
     }
     Ok(())
 }
@@ -61,32 +61,32 @@ pub fn write_node_label<W: Write, INIT, FINI>(block: BasicBlock,
 {
     let data = mir.basic_block_data(block);
 
-    try!(write!(w, r#"<table border="0" cellborder="1" cellspacing="0">"#));
+    write!(w, r#"<table border="0" cellborder="1" cellspacing="0">"#)?;
 
     // Basic block number at the top.
-    try!(write!(w, r#"<tr><td {attrs} colspan="{colspan}">{blk}</td></tr>"#,
+    write!(w, r#"<tr><td {attrs} colspan="{colspan}">{blk}</td></tr>"#,
                 attrs=r#"bgcolor="gray" align="center""#,
                 colspan=num_cols,
-                blk=block.index()));
+                blk=block.index())?;
 
-    try!(init(w));
+    init(w)?;
 
     // List of statements in the middle.
     if !data.statements.is_empty() {
-        try!(write!(w, r#"<tr><td align="left" balign="left">"#));
+        write!(w, r#"<tr><td align="left" balign="left">"#)?;
         for statement in &data.statements {
-            try!(write!(w, "{}<br/>", escape(statement)));
+            write!(w, "{}<br/>", escape(statement))?;
         }
-        try!(write!(w, "</td></tr>"));
+        write!(w, "</td></tr>")?;
     }
 
     // Terminator head at the bottom, not including the list of successor blocks. Those will be
     // displayed as labels on the edges between blocks.
     let mut terminator_head = String::new();
     data.terminator().fmt_head(&mut terminator_head).unwrap();
-    try!(write!(w, r#"<tr><td align="left">{}</td></tr>"#, dot::escape_html(&terminator_head)));
+    write!(w, r#"<tr><td align="left">{}</td></tr>"#, dot::escape_html(&terminator_head))?;
 
-    try!(fini(w));
+    fini(w)?;
 
     // Close the table
     writeln!(w, "</table>")
@@ -95,8 +95,8 @@ pub fn write_node_label<W: Write, INIT, FINI>(block: BasicBlock,
 /// Write a graphviz DOT node for the given basic block.
 fn write_node<W: Write>(block: BasicBlock, mir: &Mir, w: &mut W) -> io::Result<()> {
     // Start a new node with the label to follow, in one of DOT's pseudo-HTML tables.
-    try!(write!(w, r#"    {} [shape="none", label=<"#, node(block)));
-    try!(write_node_label(block, mir, w, 1, |_| Ok(()), |_| Ok(())));
+    write!(w, r#"    {} [shape="none", label=<"#, node(block))?;
+    write_node_label(block, mir, w, 1, |_| Ok(()), |_| Ok(()))?;
     // Close the node label and the node itself.
     writeln!(w, ">];")
 }
@@ -107,7 +107,7 @@ fn write_edges<W: Write>(source: BasicBlock, mir: &Mir, w: &mut W) -> io::Result
     let labels = terminator.fmt_successor_labels();
 
     for (&target, label) in terminator.successors().iter().zip(labels) {
-        try!(writeln!(w, r#"    {} -> {} [label="{}"];"#, node(source), node(target), label));
+        writeln!(w, r#"    {} -> {} [label="{}"];"#, node(source), node(target), label)?;
     }
 
     Ok(())
@@ -118,40 +118,40 @@ fn write_edges<W: Write>(source: BasicBlock, mir: &Mir, w: &mut W) -> io::Result
 /// all the variables and temporaries.
 fn write_graph_label<W: Write>(tcx: &ty::TyCtxt, nid: NodeId, mir: &Mir, w: &mut W)
 -> io::Result<()> {
-    try!(write!(w, "    label=<fn {}(", dot::escape_html(&tcx.map.path_to_string(nid))));
+    write!(w, "    label=<fn {}(", dot::escape_html(&tcx.map.path_to_string(nid)))?;
 
     // fn argument types.
     for (i, arg) in mir.arg_decls.iter().enumerate() {
         if i > 0 {
-            try!(write!(w, ", "));
+            write!(w, ", ")?;
         }
-        try!(write!(w, "{:?}: {}", Lvalue::Arg(i as u32), escape(&arg.ty)));
+        write!(w, "{:?}: {}", Lvalue::Arg(i as u32), escape(&arg.ty))?;
     }
 
-    try!(write!(w, ") -&gt; "));
+    write!(w, ") -&gt; ")?;
 
     // fn return type.
     match mir.return_ty {
-        ty::FnOutput::FnConverging(ty) => try!(write!(w, "{}", escape(ty))),
-        ty::FnOutput::FnDiverging => try!(write!(w, "!")),
+        ty::FnOutput::FnConverging(ty) => write!(w, "{}", escape(ty))?,
+        ty::FnOutput::FnDiverging => write!(w, "!")?,
     }
 
-    try!(write!(w, r#"<br align="left"/>"#));
+    write!(w, r#"<br align="left"/>"#)?;
 
     // User variable types (including the user's name in a comment).
     for (i, var) in mir.var_decls.iter().enumerate() {
-        try!(write!(w, "let "));
+        write!(w, "let ")?;
         if var.mutability == Mutability::Mut {
-            try!(write!(w, "mut "));
+            write!(w, "mut ")?;
         }
-        try!(write!(w, r#"{:?}: {}; // {}<br align="left"/>"#,
-                    Lvalue::Var(i as u32), escape(&var.ty), var.name));
+        write!(w, r#"{:?}: {}; // {}<br align="left"/>"#,
+                    Lvalue::Var(i as u32), escape(&var.ty), var.name)?;
     }
 
     // Compiler-introduced temporary types.
     for (i, temp) in mir.temp_decls.iter().enumerate() {
-        try!(write!(w, r#"let mut {:?}: {};<br align="left"/>"#,
-                    Lvalue::Temp(i as u32), escape(&temp.ty)));
+        write!(w, r#"let mut {:?}: {};<br align="left"/>"#,
+                    Lvalue::Temp(i as u32), escape(&temp.ty))?;
     }
 
     writeln!(w, ">;")

src/librustc_mir/pretty.rs

@@ -19,12 +19,12 @@ const INDENT: &'static str = "    ";
 pub fn write_mir_pretty<'a, 't, W, I>(tcx: &ty::TyCtxt<'t>, iter: I, w: &mut W) -> io::Result<()>
 where W: Write, I: Iterator<Item=(&'a NodeId, &'a Mir<'a>)> {
     for (&nodeid, mir) in iter {
-        try!(write_mir_intro(tcx, nodeid, mir, w));
+        write_mir_intro(tcx, nodeid, mir, w)?;
         // Nodes
         for block in mir.all_basic_blocks() {
-            try!(write_basic_block(block, mir, w));
+            write_basic_block(block, mir, w)?;
         }
-        try!(writeln!(w, "}}"))
+        writeln!(w, "}}")?
     }
     Ok(())
 }
@@ -34,15 +34,15 @@ fn write_basic_block<W: Write>(block: BasicBlock, mir: &Mir, w: &mut W) -> io::R
     let data = mir.basic_block_data(block);
 
     // Basic block label at the top.
-    try!(writeln!(w, "\n{}{:?}: {{", INDENT, block));
+    writeln!(w, "\n{}{:?}: {{", INDENT, block)?;
 
     // List of statements in the middle.
     for statement in &data.statements {
-        try!(writeln!(w, "{0}{0}{1:?};", INDENT, statement));
+        writeln!(w, "{0}{0}{1:?};", INDENT, statement)?;
     }
 
     // Terminator at the bottom.
-    try!(writeln!(w, "{0}{0}{1:?};", INDENT, data.terminator()));
+    writeln!(w, "{0}{0}{1:?};", INDENT, data.terminator())?;
 
     writeln!(w, "{}}}", INDENT)
 }
@@ -52,38 +52,38 @@ fn write_basic_block<W: Write>(block: BasicBlock, mir: &Mir, w: &mut W) -> io::R
 fn write_mir_intro<W: Write>(tcx: &ty::TyCtxt, nid: NodeId, mir: &Mir, w: &mut W)
 -> io::Result<()> {
 
-    try!(write!(w, "fn {}(", tcx.map.path_to_string(nid)));
+    write!(w, "fn {}(", tcx.map.path_to_string(nid))?;
 
     // fn argument types.
     for (i, arg) in mir.arg_decls.iter().enumerate() {
         if i > 0 {
-            try!(write!(w, ", "));
+            write!(w, ", ")?;
         }
-        try!(write!(w, "{:?}: {}", Lvalue::Arg(i as u32), arg.ty));
+        write!(w, "{:?}: {}", Lvalue::Arg(i as u32), arg.ty)?;
     }
 
-    try!(write!(w, ") -> "));
+    write!(w, ") -> ")?;
 
     // fn return type.
     match mir.return_ty {
-        ty::FnOutput::FnConverging(ty) => try!(write!(w, "{}", ty)),
-        ty::FnOutput::FnDiverging => try!(write!(w, "!")),
+        ty::FnOutput::FnConverging(ty) => write!(w, "{}", ty)?,
+        ty::FnOutput::FnDiverging => write!(w, "!")?,
     }
 
-    try!(writeln!(w, " {{"));
+    writeln!(w, " {{")?;
 
     // User variable types (including the user's name in a comment).
     for (i, var) in mir.var_decls.iter().enumerate() {
-        try!(write!(w, "{}let ", INDENT));
+        write!(w, "{}let ", INDENT)?;
         if var.mutability == Mutability::Mut {
-            try!(write!(w, "mut "));
+            write!(w, "mut ")?;
         }
-        try!(writeln!(w, "{:?}: {}; // {}", Lvalue::Var(i as u32), var.ty, var.name));
+        writeln!(w, "{:?}: {}; // {}", Lvalue::Var(i as u32), var.ty, var.name)?;
     }
 
     // Compiler-introduced temporary types.
     for (i, temp) in mir.temp_decls.iter().enumerate() {
-        try!(writeln!(w, "{}let mut {:?}: {};", INDENT, Lvalue::Temp(i as u32), temp.ty));
+        writeln!(w, "{}let mut {:?}: {};", INDENT, Lvalue::Temp(i as u32), temp.ty)?;
     }
 
     Ok(())

src/librustc_trans/back/archive.rs

@@ -254,8 +254,8 @@ impl<'a> ArchiveBuilder<'a> {
         // want to modify this archive, so we use `io::copy` to not preserve
         // permission bits.
         if let Some(ref s) = self.config.src {
-            try!(io::copy(&mut try!(File::open(s)),
-                          &mut try!(File::create(&self.config.dst))));
+            io::copy(&mut File::open(s)?,
+                          &mut File::create(&self.config.dst)?)?;
         }
 
         if removals.len() > 0 {
@@ -267,12 +267,12 @@ impl<'a> ArchiveBuilder<'a> {
             match addition {
                 Addition::File { path, name_in_archive } => {
                     let dst = self.work_dir.path().join(&name_in_archive);
-                    try!(fs::copy(&path, &dst));
+                    fs::copy(&path, &dst)?;
                     members.push(PathBuf::from(name_in_archive));
                 }
                 Addition::Archive { archive, archive_name, mut skip } => {
-                    try!(self.add_archive_members(&mut members, archive,
-                                                  &archive_name, &mut *skip));
+                    self.add_archive_members(&mut members, archive,
+                                                  &archive_name, &mut *skip)?;
                 }
             }
         }
@@ -334,7 +334,7 @@ impl<'a> ArchiveBuilder<'a> {
         // all SYMDEF files as these are just magical placeholders which get
         // re-created when we make a new archive anyway.
         for file in archive.iter() {
-            let file = try!(file.map_err(string_to_io_error));
+            let file = file.map_err(string_to_io_error)?;
             if !is_relevant_child(&file) {
                 continue
             }
@@ -388,7 +388,7 @@ impl<'a> ArchiveBuilder<'a> {
                 }
             }
             let dst = self.work_dir.path().join(&new_filename);
-            try!(try!(File::create(&dst)).write_all(file.data()));
+            File::create(&dst)?.write_all(file.data())?;
             members.push(PathBuf::from(new_filename));
         }
         Ok(())
@@ -455,7 +455,7 @@ impl<'a> ArchiveBuilder<'a> {
         unsafe {
             if let Some(archive) = self.src_archive() {
                 for child in archive.iter() {
-                    let child = try!(child.map_err(string_to_io_error));
+                    let child = child.map_err(string_to_io_error)?;
                     let child_name = match child.name() {
                         Some(s) => s,
                         None => continue,
@@ -464,7 +464,7 @@ impl<'a> ArchiveBuilder<'a> {
                         continue
                     }
 
-                    let name = try!(CString::new(child_name));
+                    let name = CString::new(child_name)?;
                     members.push(llvm::LLVMRustArchiveMemberNew(ptr::null(),
                                                                 name.as_ptr(),
                                                                 child.raw()));
@@ -474,8 +474,8 @@ impl<'a> ArchiveBuilder<'a> {
             for addition in mem::replace(&mut self.additions, Vec::new()) {
                 match addition {
                     Addition::File { path, name_in_archive } => {
-                        let path = try!(CString::new(path.to_str().unwrap()));
-                        let name = try!(CString::new(name_in_archive));
+                        let path = CString::new(path.to_str().unwrap())?;
+                        let name = CString::new(name_in_archive)?;
                         members.push(llvm::LLVMRustArchiveMemberNew(path.as_ptr(),
                                                                     name.as_ptr(),
                                                                     ptr::null_mut()));
@@ -484,7 +484,7 @@ impl<'a> ArchiveBuilder<'a> {
                     }
                     Addition::Archive { archive, archive_name: _, mut skip } => {
                         for child in archive.iter() {
-                            let child = try!(child.map_err(string_to_io_error));
+                            let child = child.map_err(string_to_io_error)?;
                             if !is_relevant_child(&child) {
                                 continue
                             }
@@ -502,7 +502,7 @@ impl<'a> ArchiveBuilder<'a> {
                             let child_name = Path::new(child_name)
                                                   .file_name().unwrap()
                                                   .to_str().unwrap();
-                            let name = try!(CString::new(child_name));
+                            let name = CString::new(child_name)?;
                             let m = llvm::LLVMRustArchiveMemberNew(ptr::null(),
                                                                    name.as_ptr(),
                                                                    child.raw());
@@ -515,7 +515,7 @@ impl<'a> ArchiveBuilder<'a> {
             }
 
             let dst = self.config.dst.to_str().unwrap().as_bytes();
-            let dst = try!(CString::new(dst));
+            let dst = CString::new(dst)?;
             let r = llvm::LLVMRustWriteArchive(dst.as_ptr(),
                                                members.len() as libc::size_t,
                                                members.as_ptr(),

src/librustc_trans/back/link.rs

@@ -757,9 +757,9 @@ fn write_rlib_bytecode_object_v1(writer: &mut Write,
                                  bc_data_deflated: &[u8]) -> io::Result<()> {
     let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
 
-    try!(writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC));
-    try!(writer.write_all(&[1, 0, 0, 0]));
-    try!(writer.write_all(&[
+    writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC)?;
+    writer.write_all(&[1, 0, 0, 0])?;
+    writer.write_all(&[
         (bc_data_deflated_size >>  0) as u8,
         (bc_data_deflated_size >>  8) as u8,
         (bc_data_deflated_size >> 16) as u8,
@@ -768,8 +768,8 @@ fn write_rlib_bytecode_object_v1(writer: &mut Write,
         (bc_data_deflated_size >> 40) as u8,
         (bc_data_deflated_size >> 48) as u8,
         (bc_data_deflated_size >> 56) as u8,
-    ]));
-    try!(writer.write_all(&bc_data_deflated));
+    ])?;
+    writer.write_all(&bc_data_deflated)?;
 
     let number_of_bytes_written_so_far =
         RLIB_BYTECODE_OBJECT_MAGIC.len() +                // magic id
@@ -781,7 +781,7 @@ fn write_rlib_bytecode_object_v1(writer: &mut Write,
     // padding byte to make it even. This works around a crash bug in LLDB
     // (see issue #15950)
     if number_of_bytes_written_so_far % 2 == 1 {
-        try!(writer.write_all(&[0]));
+        writer.write_all(&[0])?;
     }
 
     return Ok(());

src/librustc_trans/back/linker.rs

@@ -327,16 +327,16 @@ impl<'a> Linker for MsvcLinker<'a> {
                       tmpdir: &Path) {
         let path = tmpdir.join("lib.def");
         let res = (|| -> io::Result<()> {
-            let mut f = BufWriter::new(try!(File::create(&path)));
+            let mut f = BufWriter::new(File::create(&path)?);
 
             // Start off with the standard module name header and then go
             // straight to exports.
-            try!(writeln!(f, "LIBRARY"));
-            try!(writeln!(f, "EXPORTS"));
+            writeln!(f, "LIBRARY")?;
+            writeln!(f, "EXPORTS")?;
 
             // Write out all our local symbols
             for sym in trans.reachable.iter() {
-                try!(writeln!(f, "  {}", sym));
+                writeln!(f, "  {}", sym)?;
             }
 
             // Take a look at how all upstream crates are linked into this
@@ -357,7 +357,7 @@ impl<'a> Linker for MsvcLinker<'a> {
                 cstore.item_symbol(did)
             });
             for symbol in symbols {
-                try!(writeln!(f, "  {}", symbol));
+                writeln!(f, "  {}", symbol)?;
             }
             Ok(())
         })();

src/librustc_trans/trans/cleanup.rs

@@ -175,9 +175,9 @@ impl<'blk, 'tcx: 'blk> fmt::Debug for CleanupScopeKind<'blk, 'tcx> {
             CustomScopeKind => write!(f, "CustomScopeKind"),
             AstScopeKind(nid) => write!(f, "AstScopeKind({})", nid),
             LoopScopeKind(nid, ref blks) => {
-                try!(write!(f, "LoopScopeKind({}, [", nid));
+                write!(f, "LoopScopeKind({}, [", nid)?;
                 for blk in blks {
-                    try!(write!(f, "{:p}, ", blk));
+                    write!(f, "{:p}, ", blk)?;
                 }
                 write!(f, "])")
             }

src/librustc_trans/trans/consts.rs

@@ -316,9 +316,9 @@ pub fn get_const_expr_as_global<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
     let val = if qualif.intersects(ConstQualif::NON_STATIC_BORROWS) {
         // Avoid autorefs as they would create global instead of stack
         // references, even when only the latter are correct.
-        try!(const_expr_unadjusted(ccx, expr, ty, param_substs, None, trueconst))
+        const_expr_unadjusted(ccx, expr, ty, param_substs, None, trueconst)?
     } else {
-        try!(const_expr(ccx, expr, param_substs, None, trueconst)).0
+        const_expr(ccx, expr, param_substs, None, trueconst)?.0
     };
 
     // boolean SSA values are i1, but they have to be stored in i8 slots,
@@ -344,7 +344,7 @@ pub fn const_expr<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
                             -> Result<(ValueRef, Ty<'tcx>), ConstEvalFailure> {
     let ety = monomorphize::apply_param_substs(cx.tcx(), param_substs,
                                                &cx.tcx().expr_ty(e));
-    let llconst = try!(const_expr_unadjusted(cx, e, ety, param_substs, fn_args, trueconst));
+    let llconst = const_expr_unadjusted(cx, e, ety, param_substs, fn_args, trueconst)?;
     let mut llconst = llconst;
     let mut ety_adjusted = monomorphize::apply_param_substs(cx.tcx(), param_substs,
                                                             &cx.tcx().expr_ty_adjusted(e));
@@ -594,18 +594,18 @@ fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
         hir::ExprBinary(b, ref e1, ref e2) => {
             /* Neither type is bottom, and we expect them to be unified
              * already, so the following is safe. */
-            let (te1, ty) = try!(const_expr(cx, &e1, param_substs, fn_args, trueconst));
+            let (te1, ty) = const_expr(cx, &e1, param_substs, fn_args, trueconst)?;
             debug!("const_expr_unadjusted: te1={:?}, ty={:?}",
                    Value(te1), ty);
             assert!(!ty.is_simd());
             let is_float = ty.is_fp();
             let signed = ty.is_signed();
 
-            let (te2, ty2) = try!(const_expr(cx, &e2, param_substs, fn_args, trueconst));
+            let (te2, ty2) = const_expr(cx, &e2, param_substs, fn_args, trueconst)?;
             debug!("const_expr_unadjusted: te2={:?}, ty={:?}",
                    Value(te2), ty2);
 
-            try!(check_binary_expr_validity(cx, e, ty, te1, te2, trueconst));
+            check_binary_expr_validity(cx, e, ty, te1, te2, trueconst)?;
 
             unsafe { match b.node {
                 hir::BiAdd if is_float => llvm::LLVMConstFAdd(te1, te2),
@@ -651,9 +651,9 @@ fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
             } } // unsafe { match b.node {
         },
         hir::ExprUnary(u, ref inner_e) => {
-            let (te, ty) = try!(const_expr(cx, &inner_e, param_substs, fn_args, trueconst));
+            let (te, ty) = const_expr(cx, &inner_e, param_substs, fn_args, trueconst)?;
 
-            try!(check_unary_expr_validity(cx, e, ty, te, trueconst));
+            check_unary_expr_validity(cx, e, ty, te, trueconst)?;
 
             let is_float = ty.is_fp();
             unsafe { match u {
@@ -664,21 +664,21 @@ fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
             } }
         },
         hir::ExprField(ref base, field) => {
-            let (bv, bt) = try!(const_expr(cx, &base, param_substs, fn_args, trueconst));
+            let (bv, bt) = const_expr(cx, &base, param_substs, fn_args, trueconst)?;
             let brepr = adt::represent_type(cx, bt);
             let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
             let ix = vinfo.field_index(field.node);
             adt::const_get_field(cx, &brepr, bv, vinfo.discr, ix)
         },
         hir::ExprTupField(ref base, idx) => {
-            let (bv, bt) = try!(const_expr(cx, &base, param_substs, fn_args, trueconst));
+            let (bv, bt) = const_expr(cx, &base, param_substs, fn_args, trueconst)?;
             let brepr = adt::represent_type(cx, bt);
             let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
             adt::const_get_field(cx, &brepr, bv, vinfo.discr, idx.node)
         },
         hir::ExprIndex(ref base, ref index) => {
-            let (bv, bt) = try!(const_expr(cx, &base, param_substs, fn_args, trueconst));
-            let iv = try!(const_expr(cx, &index, param_substs, fn_args, TrueConst::Yes)).0;
+            let (bv, bt) = const_expr(cx, &base, param_substs, fn_args, trueconst)?;
+            let iv = const_expr(cx, &index, param_substs, fn_args, TrueConst::Yes)?.0;
             let iv = if let Some(iv) = const_to_opt_uint(iv) {
                 iv
             } else {
@@ -729,7 +729,7 @@ fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
         hir::ExprCast(ref base, _) => {
             let t_cast = ety;
             let llty = type_of::type_of(cx, t_cast);
-            let (v, t_expr) = try!(const_expr(cx, &base, param_substs, fn_args, trueconst));
+            let (v, t_expr) = const_expr(cx, &base, param_substs, fn_args, trueconst)?;
             debug!("trans_const_cast({:?} as {:?})", t_expr, t_cast);
             if expr::cast_is_noop(cx.tcx(), base, t_expr, t_cast) {
                 return Ok(v);
@@ -811,30 +811,30 @@ fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
             } else {
                 // If this isn't the address of a static, then keep going through
                 // normal constant evaluation.
-                let (v, ty) = try!(const_expr(cx, &sub, param_substs, fn_args, trueconst));
+                let (v, ty) = const_expr(cx, &sub, param_substs, fn_args, trueconst)?;
                 addr_of(cx, v, type_of::align_of(cx, ty), "ref")
             }
         },
         hir::ExprAddrOf(hir::MutMutable, ref sub) => {
-            let (v, ty) = try!(const_expr(cx, &sub, param_substs, fn_args, trueconst));
+            let (v, ty) = const_expr(cx, &sub, param_substs, fn_args, trueconst)?;
             addr_of_mut(cx, v, type_of::align_of(cx, ty), "ref_mut_slice")
         },
         hir::ExprTup(ref es) => {
             let repr = adt::represent_type(cx, ety);
-            let vals = try!(map_list(&es[..]));
+            let vals = map_list(&es[..])?;
             adt::trans_const(cx, &repr, Disr(0), &vals[..])
         },
         hir::ExprStruct(_, ref fs, ref base_opt) => {
             let repr = adt::represent_type(cx, ety);
 
             let base_val = match *base_opt {
-                Some(ref base) => Some(try!(const_expr(
+                Some(ref base) => Some(const_expr(
                     cx,
                     &base,
                     param_substs,
                     fn_args,
                     trueconst,
-                ))),
+                )?),
                 None => None
             };
 
@@ -851,7 +851,7 @@ fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
             .collect::<Vec<Result<_, ConstEvalFailure>>>()
             .into_iter()
             .collect::<Result<Vec<_>,ConstEvalFailure>>();
-            let cs = try!(cs);
+            let cs = cs?;
             if ety.is_simd() {
                 C_vector(&cs[..])
             } else {
@@ -872,7 +872,7 @@ fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
                        .collect::<Vec<Result<_, ConstEvalFailure>>>()
                        .into_iter()
                        .collect::<Result<Vec<_>, ConstEvalFailure>>();
-            let vs = try!(vs);
+            let vs = vs?;
             // If the vector contains enums, an LLVM array won't work.
             if vs.iter().any(|vi| val_ty(*vi) != llunitty) {
                 C_struct(cx, &vs[..], false)
@@ -884,7 +884,7 @@ fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
             let unit_ty = ety.sequence_element_type(cx.tcx());
             let llunitty = type_of::type_of(cx, unit_ty);
             let n = cx.tcx().eval_repeat_count(count);
-            let unit_val = try!(const_expr(cx, &elem, param_substs, fn_args, trueconst)).0;
+            let unit_val = const_expr(cx, &elem, param_substs, fn_args, trueconst)?.0;
             let vs = vec![unit_val; n];
             if val_ty(unit_val) != llunitty {
                 C_struct(cx, &vs[..], false)
@@ -904,7 +904,7 @@ fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
                 }
                 Def::Fn(..) | Def::Method(..) => C_nil(cx),
                 Def::Const(def_id) | Def::AssociatedConst(def_id) => {
-                    load_const(cx, try!(get_const_val(cx, def_id, e, param_substs)),
+                    load_const(cx, get_const_val(cx, def_id, e, param_substs)?,
                                ety)
                 }
                 Def::Variant(enum_did, variant_did) => {
@@ -940,17 +940,17 @@ fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
                 };
             }
             let def = cx.tcx().def_map.borrow()[&callee.id].full_def();
-            let arg_vals = try!(map_list(args));
+            let arg_vals = map_list(args)?;
             match def {
                 Def::Fn(did) | Def::Method(did) => {
-                    try!(const_fn_call(
+                    const_fn_call(
                         cx,
                         did,
                         cx.tcx().node_id_item_substs(callee.id).substs,
                         &arg_vals,
                         param_substs,
                         trueconst,
-                    ))
+                    )?
                 }
                 Def::Struct(..) => {
                     if ety.is_simd() {
@@ -972,22 +972,22 @@ fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
             }
         },
         hir::ExprMethodCall(_, _, ref args) => {
-            let arg_vals = try!(map_list(args));
+            let arg_vals = map_list(args)?;
             let method_call = ty::MethodCall::expr(e.id);
             let method = cx.tcx().tables.borrow().method_map[&method_call];
-            try!(const_fn_call(cx, method.def_id, method.substs.clone(),
-                               &arg_vals, param_substs, trueconst))
+            const_fn_call(cx, method.def_id, method.substs.clone(),
+                               &arg_vals, param_substs, trueconst)?
         },
-        hir::ExprType(ref e, _) => try!(const_expr(cx, &e, param_substs, fn_args, trueconst)).0,
+        hir::ExprType(ref e, _) => const_expr(cx, &e, param_substs, fn_args, trueconst)?.0,
         hir::ExprBlock(ref block) => {
             match block.expr {
-                Some(ref expr) => try!(const_expr(
+                Some(ref expr) => const_expr(
                     cx,
                     &expr,
                     param_substs,
                     fn_args,
                     trueconst,
-                )).0,
+                )?.0,
                 None => C_nil(cx),
             }
         },
@@ -1149,13 +1149,13 @@ pub fn trans_static(ccx: &CrateContext,
         let datum = get_static(ccx, def_id);
 
         let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
-        let (v, _) = try!(const_expr(
+        let (v, _) = const_expr(
             ccx,
             expr,
             empty_substs,
             None,
             TrueConst::Yes,
-        ).map_err(|e| e.into_inner()));
+        ).map_err(|e| e.into_inner())?;
 
         // boolean SSA values are i1, but they have to be stored in i8 slots,
         // otherwise some LLVM optimization passes don't work as expected

src/librustc_typeck/astconv.rs

@@ -934,7 +934,7 @@ fn ast_type_binding_to_poly_projection_predicate<'tcx>(
                                                  tcx.mk_substs(dummy_substs)));
     }
 
-    try!(this.ensure_super_predicates(binding.span, trait_ref.def_id()));
+    this.ensure_super_predicates(binding.span, trait_ref.def_id())?;
 
     let mut candidates: Vec<ty::PolyTraitRef> =
         traits::supertraits(tcx, trait_ref.clone())
@@ -953,11 +953,11 @@ fn ast_type_binding_to_poly_projection_predicate<'tcx>(
         }
     }
 
-    let candidate = try!(one_bound_for_assoc_type(tcx,
+    let candidate = one_bound_for_assoc_type(tcx,
                                                   candidates,
                                                   &trait_ref.to_string(),
                                                   &binding.item_name.as_str(),
-                                                  binding.span));
+                                                  binding.span)?;
 
     Ok(ty::Binder(ty::ProjectionPredicate {             // <-------------------------+
         projection_ty: ty::ProjectionTy {               //                           |

src/librustc_typeck/check/coercion.rs

@@ -220,7 +220,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
 
         let (r_a, mt_a) = match a.sty {
             ty::TyRef(r_a, mt_a) => {
-                try!(coerce_mutbls(mt_a.mutbl, mt_b.mutbl));
+                coerce_mutbls(mt_a.mutbl, mt_b.mutbl)?;
                 (r_a, mt_a)
             }
             _ => return self.unify_and_identity(a, b)
@@ -414,7 +414,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
         // Handle reborrows before selecting `Source: CoerceUnsized<Target>`.
         let (source, reborrow) = match (&source.sty, &target.sty) {
             (&ty::TyRef(_, mt_a), &ty::TyRef(_, mt_b)) => {
-                try!(coerce_mutbls(mt_a.mutbl, mt_b.mutbl));
+                coerce_mutbls(mt_a.mutbl, mt_b.mutbl)?;
 
                 let coercion = Coercion(self.origin.span());
                 let r_borrow = self.fcx.infcx().next_region_var(coercion);
@@ -422,7 +422,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
                 (mt_a.ty, Some(AutoPtr(region, mt_b.mutbl)))
             }
             (&ty::TyRef(_, mt_a), &ty::TyRawPtr(mt_b)) => {
-                try!(coerce_mutbls(mt_a.mutbl, mt_b.mutbl));
+                coerce_mutbls(mt_a.mutbl, mt_b.mutbl)?;
                 (mt_a.ty, Some(AutoUnsafe(mt_b.mutbl)))
             }
             _ => (source, None)
@@ -564,8 +564,8 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
 
         // Check that the types which they point at are compatible.
         let a_unsafe = self.tcx().mk_ptr(ty::TypeAndMut{ mutbl: mutbl_b, ty: mt_a.ty });
-        let (ty, noop) = try!(self.unify_and_identity(a_unsafe, b));
-        try!(coerce_mutbls(mt_a.mutbl, mutbl_b));
+        let (ty, noop) = self.unify_and_identity(a_unsafe, b)?;
+        coerce_mutbls(mt_a.mutbl, mutbl_b)?;
 
         // Although references and unsafe ptrs have the same
         // representation, we still register an AutoDerefRef so that
@@ -592,7 +592,7 @@ fn apply<'a, 'b, 'tcx, E, I>(coerce: &mut Coerce<'a, 'tcx>,
     where E: Fn() -> I,
           I: IntoIterator<Item=&'b hir::Expr> {
 
-    let (ty, adjustment) = try!(indent(|| coerce.coerce(exprs, a, b)));
+    let (ty, adjustment) = indent(|| coerce.coerce(exprs, a, b))?;
 
     let fcx = coerce.fcx;
     if let AdjustDerefRef(auto) = adjustment {
@@ -621,7 +621,7 @@ pub fn try<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
     let mut coerce = Coerce::new(fcx, TypeOrigin::ExprAssignable(expr.span));
     fcx.infcx().commit_if_ok(|_| {
         let (ty, adjustment) =
-            try!(apply(&mut coerce, &|| Some(expr), source, target));
+            apply(&mut coerce, &|| Some(expr), source, target)?;
         if !adjustment.is_identity() {
             debug!("Success, coerced with {:?}", adjustment);
             assert!(!fcx.inh.tables.borrow().adjustments.contains_key(&expr.id));
@@ -657,7 +657,7 @@ pub fn try_find_lub<'a, 'b, 'tcx, E, I>(fcx: &FnCtxt<'a, 'tcx>,
         (&ty::TyFnDef(a_def_id, a_substs, a_fty),
          &ty::TyFnDef(b_def_id, b_substs, b_fty)) => {
             // The signature must always match.
-            let fty = try!(lub.relate(a_fty, b_fty));
+            let fty = lub.relate(a_fty, b_fty)?;
 
             if a_def_id == b_def_id {
                 // Same function, maybe the parameters match.

src/librustc_typeck/check/compare_method.rs

@@ -323,7 +323,7 @@ pub fn compare_impl_method<'tcx>(tcx: &TyCtxt<'tcx>,
         debug!("compare_impl_method: trait_fty={:?}",
                trait_fty);
 
-        try!(infer::mk_subty(&infcx, false, origin, impl_fty, trait_fty));
+        infer::mk_subty(&infcx, false, origin, impl_fty, trait_fty)?;
 
         infcx.leak_check(&skol_map, snapshot)
     });

src/librustc_typeck/check/dropck.rs

@@ -46,11 +46,11 @@ pub fn check_drop_impl(tcx: &TyCtxt, drop_impl_did: DefId) -> Result<(), ()> {
     match dtor_self_type.sty {
         ty::TyEnum(adt_def, self_to_impl_substs) |
         ty::TyStruct(adt_def, self_to_impl_substs) => {
-            try!(ensure_drop_params_and_item_params_correspond(tcx,
+            ensure_drop_params_and_item_params_correspond(tcx,
                                                                drop_impl_did,
                                                                dtor_generics,
                                                                &dtor_self_type,
-                                                               adt_def.did));
+                                                               adt_def.did)?;
 
             ensure_drop_predicates_are_implied_by_item_defn(tcx,
                                                             drop_impl_did,
@@ -452,7 +452,7 @@ fn iterate_over_potentially_unsafe_regions_in_type<'a, 'b, 'tcx>(
                     let fty = field.ty(tcx, substs);
                     let fty = cx.rcx.fcx.resolve_type_vars_if_possible(
                         cx.rcx.fcx.normalize_associated_types_in(cx.span, &fty));
-                    try!(iterate_over_potentially_unsafe_regions_in_type(
+                    iterate_over_potentially_unsafe_regions_in_type(
                         cx,
                         TypeContext::ADT {
                             def_id: did,
@@ -460,7 +460,7 @@ fn iterate_over_potentially_unsafe_regions_in_type<'a, 'b, 'tcx>(
                             variant: variant.name,
                         },
                         fty,
-                        depth+1))
+                        depth+1)?
                 }
             }
             Ok(())
@@ -469,8 +469,8 @@ fn iterate_over_potentially_unsafe_regions_in_type<'a, 'b, 'tcx>(
         ty::TyTuple(ref tys) |
         ty::TyClosure(_, box ty::ClosureSubsts { upvar_tys: ref tys, .. }) => {
             for ty in tys {
-                try!(iterate_over_potentially_unsafe_regions_in_type(
-                    cx, context, ty, depth+1))
+                iterate_over_potentially_unsafe_regions_in_type(
+                    cx, context, ty, depth+1)?
             }
             Ok(())
         }

src/librustc_typeck/check/method/mod.rs

@@ -124,7 +124,7 @@ pub fn lookup<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
 
     let mode = probe::Mode::MethodCall;
     let self_ty = fcx.infcx().resolve_type_vars_if_possible(&self_ty);
-    let pick = try!(probe::probe(fcx, span, mode, method_name, self_ty, call_expr.id));
+    let pick = probe::probe(fcx, span, mode, method_name, self_ty, call_expr.id)?;
     Ok(confirm::confirm(fcx, span, self_expr, call_expr, self_ty, pick, supplied_method_types))
 }
 
@@ -337,7 +337,7 @@ pub fn resolve_ufcs<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
                               -> Result<Def, MethodError<'tcx>>
 {
     let mode = probe::Mode::Path;
-    let pick = try!(probe::probe(fcx, span, mode, method_name, self_ty, expr_id));
+    let pick = probe::probe(fcx, span, mode, method_name, self_ty, expr_id)?;
     let def = pick.item.def();
 
     if let probe::InherentImplPick = pick.kind {

src/librustc_typeck/check/method/probe.rs

@@ -186,7 +186,7 @@ pub fn probe<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
                                              steps,
                                              opt_simplified_steps);
         probe_cx.assemble_inherent_candidates();
-        try!(probe_cx.assemble_extension_candidates_for_traits_in_scope(scope_expr_id));
+        probe_cx.assemble_extension_candidates_for_traits_in_scope(scope_expr_id)?;
         probe_cx.pick()
     })
 }
@@ -568,7 +568,7 @@ impl<'a,'tcx> ProbeContext<'a,'tcx> {
         if let Some(applicable_traits) = opt_applicable_traits {
             for &trait_did in applicable_traits {
                 if duplicates.insert(trait_did) {
-                    try!(self.assemble_extension_candidates_for_trait(trait_did));
+                    self.assemble_extension_candidates_for_trait(trait_did)?;
                 }
             }
         }
@@ -579,7 +579,7 @@ impl<'a,'tcx> ProbeContext<'a,'tcx> {
         let mut duplicates = HashSet::new();
         for trait_info in suggest::all_traits(self.fcx.ccx) {
             if duplicates.insert(trait_info.def_id) {
-                try!(self.assemble_extension_candidates_for_trait(trait_info.def_id));
+                self.assemble_extension_candidates_for_trait(trait_info.def_id)?;
             }
         }
         Ok(())
@@ -612,7 +612,7 @@ impl<'a,'tcx> ProbeContext<'a,'tcx> {
 
         self.assemble_extension_candidates_for_trait_impls(trait_def_id, item.clone());
 
-        try!(self.assemble_closure_candidates(trait_def_id, item.clone()));
+        self.assemble_closure_candidates(trait_def_id, item.clone())?;
 
         self.assemble_projection_candidates(trait_def_id, item.clone());
 
@@ -854,7 +854,7 @@ impl<'a,'tcx> ProbeContext<'a,'tcx> {
         let span = self.span;
         let tcx = self.tcx();
 
-        try!(self.assemble_extension_candidates_for_all_traits());
+        self.assemble_extension_candidates_for_all_traits()?;
 
         let out_of_scope_traits = match self.pick_core() {
             Some(Ok(p)) => vec![p.item.container().id()],

src/librustc_typeck/collect.rs

@@ -292,7 +292,7 @@ impl<'a,'tcx> CrateCtxt<'a,'tcx> {
             let def_ids = ensure_super_predicates_step(self, trait_def_id);
 
             for def_id in def_ids {
-                try!(self.ensure_super_predicates(span, def_id));
+                self.ensure_super_predicates(span, def_id)?;
             }
 
             Ok(())

src/librustc_typeck/lib.rs

@@ -339,31 +339,31 @@ pub fn check_crate(tcx: &TyCtxt, trait_map: ty::TraitMap) -> CompileResult {
 
     // this ensures that later parts of type checking can assume that items
     // have valid types and not error
-    try!(tcx.sess.track_errors(|| {
+    tcx.sess.track_errors(|| {
         time(time_passes, "type collecting", ||
              collect::collect_item_types(tcx));
 
-    }));
+    })?;
 
     time(time_passes, "variance inference", ||
          variance::infer_variance(tcx));
 
-    try!(tcx.sess.track_errors(|| {
+    tcx.sess.track_errors(|| {
       time(time_passes, "coherence checking", ||
           coherence::check_coherence(&ccx));
-    }));
+    })?;
 
-    try!(time(time_passes, "wf checking", ||
-        check::check_wf_new(&ccx)));
+    time(time_passes, "wf checking", ||
+        check::check_wf_new(&ccx))?;
 
-    try!(time(time_passes, "item-types checking", ||
-        check::check_item_types(&ccx)));
+    time(time_passes, "item-types checking", ||
+        check::check_item_types(&ccx))?;
 
-    try!(time(time_passes, "item-bodies checking", ||
-        check::check_item_bodies(&ccx)));
+    time(time_passes, "item-bodies checking", ||
+        check::check_item_bodies(&ccx))?;
 
-    try!(time(time_passes, "drop-impl checking", ||
-        check::check_drop_impls(&ccx)));
+    time(time_passes, "drop-impl checking", ||
+        check::check_drop_impls(&ccx))?;
 
     check_for_entry_fn(&ccx);
 

src/librustdoc/externalfiles.rs

@@ -38,9 +38,9 @@ impl ExternalHtml {
 }
 
 pub fn load_string(input: &Path) -> io::Result<Option<String>> {
-    let mut f = try!(File::open(input));
+    let mut f = File::open(input)?;
     let mut d = Vec::new();
-    try!(f.read_to_end(&mut d));
+    f.read_to_end(&mut d)?;
     Ok(str::from_utf8(&d).map(|s| s.to_string()).ok())
 }
 

src/librustdoc/html/escape.rs

@@ -29,7 +29,7 @@ impl<'a> fmt::Display for Escape<'a> {
         for (i, ch) in s.bytes().enumerate() {
             match ch as char {
                 '<' | '>' | '&' | '\'' | '"' => {
-                    try!(fmt.write_str(&pile_o_bits[last.. i]));
+                    fmt.write_str(&pile_o_bits[last.. i])?;
                     let s = match ch as char {
                         '>' => "&gt;",
                         '<' => "&lt;",
@@ -38,7 +38,7 @@ impl<'a> fmt::Display for Escape<'a> {
                         '"' => "&quot;",
                         _ => unreachable!()
                     };
-                    try!(fmt.write_str(s));
+                    fmt.write_str(s)?;
                     last = i + 1;
                 }
                 _ => {}
@@ -46,7 +46,7 @@ impl<'a> fmt::Display for Escape<'a> {
         }
 
         if last < s.len() {
-            try!(fmt.write_str(&pile_o_bits[last..]));
+            fmt.write_str(&pile_o_bits[last..])?;
         }
         Ok(())
     }

src/librustdoc/html/format.rs

@@ -77,8 +77,8 @@ impl ConstnessSpace {
 impl<'a, T: fmt::Display> fmt::Display for CommaSep<'a, T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         for (i, item) in self.0.iter().enumerate() {
-            if i != 0 { try!(write!(f, ", ")); }
-            try!(write!(f, "{}", item));
+            if i != 0 { write!(f, ", ")?; }
+            write!(f, "{}", item)?;
         }
         Ok(())
     }
@@ -89,9 +89,9 @@ impl<'a> fmt::Display for TyParamBounds<'a> {
         let &TyParamBounds(bounds) = self;
         for (i, bound) in bounds.iter().enumerate() {
             if i > 0 {
-                try!(f.write_str(" + "));
+                f.write_str(" + ")?;
             }
-            try!(write!(f, "{}", *bound));
+            write!(f, "{}", *bound)?;
         }
         Ok(())
     }
@@ -100,36 +100,36 @@ impl<'a> fmt::Display for TyParamBounds<'a> {
 impl fmt::Display for clean::Generics {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         if self.lifetimes.is_empty() && self.type_params.is_empty() { return Ok(()) }
-        try!(f.write_str("&lt;"));
+        f.write_str("&lt;")?;
 
         for (i, life) in self.lifetimes.iter().enumerate() {
             if i > 0 {
-                try!(f.write_str(", "));
+                f.write_str(", ")?;
             }
-            try!(write!(f, "{}", *life));
+            write!(f, "{}", *life)?;
         }
 
         if !self.type_params.is_empty() {
             if !self.lifetimes.is_empty() {
-                try!(f.write_str(", "));
+                f.write_str(", ")?;
             }
             for (i, tp) in self.type_params.iter().enumerate() {
                 if i > 0 {
-                    try!(f.write_str(", "))
+                    f.write_str(", ")?
                 }
-                try!(f.write_str(&tp.name));
+                f.write_str(&tp.name)?;
 
                 if !tp.bounds.is_empty() {
-                    try!(write!(f, ": {}", TyParamBounds(&tp.bounds)));
+                    write!(f, ": {}", TyParamBounds(&tp.bounds))?;
                 }
 
                 match tp.default {
-                    Some(ref ty) => { try!(write!(f, " = {}", ty)); },
+                    Some(ref ty) => { write!(f, " = {}", ty)?; },
                     None => {}
                 };
             }
         }
-        try!(f.write_str("&gt;"));
+        f.write_str("&gt;")?;
         Ok(())
     }
 }
@@ -140,40 +140,40 @@ impl<'a> fmt::Display for WhereClause<'a> {
         if gens.where_predicates.is_empty() {
             return Ok(());
         }
-        try!(f.write_str(" <span class='where'>where "));
+        f.write_str(" <span class='where'>where ")?;
         for (i, pred) in gens.where_predicates.iter().enumerate() {
             if i > 0 {
-                try!(f.write_str(", "));
+                f.write_str(", ")?;
             }
             match pred {
                 &clean::WherePredicate::BoundPredicate { ref ty, ref bounds } => {
                     let bounds = bounds;
-                    try!(write!(f, "{}: {}", ty, TyParamBounds(bounds)));
+                    write!(f, "{}: {}", ty, TyParamBounds(bounds))?;
                 }
                 &clean::WherePredicate::RegionPredicate { ref lifetime,
                                                           ref bounds } => {
-                    try!(write!(f, "{}: ", lifetime));
+                    write!(f, "{}: ", lifetime)?;
                     for (i, lifetime) in bounds.iter().enumerate() {
                         if i > 0 {
-                            try!(f.write_str(" + "));
+                            f.write_str(" + ")?;
                         }
 
-                        try!(write!(f, "{}", lifetime));
+                        write!(f, "{}", lifetime)?;
                     }
                 }
                 &clean::WherePredicate::EqPredicate { ref lhs, ref rhs } => {
-                    try!(write!(f, "{} == {}", lhs, rhs));
+                    write!(f, "{} == {}", lhs, rhs)?;
                 }
             }
         }
-        try!(f.write_str("</span>"));
+        f.write_str("</span>")?;
         Ok(())
     }
 }
 
 impl fmt::Display for clean::Lifetime {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        try!(f.write_str(self.get_ref()));
+        f.write_str(self.get_ref())?;
         Ok(())
     }
 }
@@ -181,14 +181,14 @@ impl fmt::Display for clean::Lifetime {
 impl fmt::Display for clean::PolyTrait {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         if !self.lifetimes.is_empty() {
-            try!(f.write_str("for&lt;"));
+            f.write_str("for&lt;")?;
             for (i, lt) in self.lifetimes.iter().enumerate() {
                 if i > 0 {
-                    try!(f.write_str(", "));
+                    f.write_str(", ")?;
                 }
-                try!(write!(f, "{}", lt));
+                write!(f, "{}", lt)?;
             }
-            try!(f.write_str("&gt; "));
+            f.write_str("&gt; ")?;
         }
         write!(f, "{}", self.trait_)
     }
@@ -218,46 +218,46 @@ impl fmt::Display for clean::PathParameters {
                 ref lifetimes, ref types, ref bindings
             } => {
                 if !lifetimes.is_empty() || !types.is_empty() || !bindings.is_empty() {
-                    try!(f.write_str("&lt;"));
+                    f.write_str("&lt;")?;
                     let mut comma = false;
                     for lifetime in lifetimes {
                         if comma {
-                            try!(f.write_str(", "));
+                            f.write_str(", ")?;
                         }
                         comma = true;
-                        try!(write!(f, "{}", *lifetime));
+                        write!(f, "{}", *lifetime)?;
                     }
                     for ty in types {
                         if comma {
-                            try!(f.write_str(", "));
+                            f.write_str(", ")?;
                         }
                         comma = true;
-                        try!(write!(f, "{}", *ty));
+                        write!(f, "{}", *ty)?;
                     }
                     for binding in bindings {
                         if comma {
-                            try!(f.write_str(", "));
+                            f.write_str(", ")?;
                         }
                         comma = true;
-                        try!(write!(f, "{}", *binding));
+                        write!(f, "{}", *binding)?;
                     }
-                    try!(f.write_str("&gt;"));
+                    f.write_str("&gt;")?;
                 }
             }
             clean::PathParameters::Parenthesized { ref inputs, ref output } => {
-                try!(f.write_str("("));
+                f.write_str("(")?;
                 let mut comma = false;
                 for ty in inputs {
                     if comma {
-                        try!(f.write_str(", "));
+                        f.write_str(", ")?;
                     }
                     comma = true;
-                    try!(write!(f, "{}", *ty));
+                    write!(f, "{}", *ty)?;
                 }
-                try!(f.write_str(")"));
+                f.write_str(")")?;
                 if let Some(ref ty) = *output {
-                    try!(f.write_str(" -&gt; "));
-                    try!(write!(f, "{}", ty));
+                    f.write_str(" -&gt; ")?;
+                    write!(f, "{}", ty)?;
                 }
             }
         }
@@ -267,7 +267,7 @@ impl fmt::Display for clean::PathParameters {
 
 impl fmt::Display for clean::PathSegment {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        try!(f.write_str(&self.name));
+        f.write_str(&self.name)?;
         write!(f, "{}", self.params)
     }
 }
@@ -275,14 +275,14 @@ impl fmt::Display for clean::PathSegment {
 impl fmt::Display for clean::Path {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         if self.global {
-            try!(f.write_str("::"))
+            f.write_str("::")?
         }
 
         for (i, seg) in self.segments.iter().enumerate() {
             if i > 0 {
-                try!(f.write_str("::"))
+                f.write_str("::")?
             }
-            try!(write!(f, "{}", seg));
+            write!(f, "{}", seg)?;
         }
         Ok(())
     }
@@ -339,20 +339,20 @@ fn resolved_path(w: &mut fmt::Formatter, did: DefId, path: &clean::Path,
             Some(mut root) => {
                 for seg in &path.segments[..amt] {
                     if "super" == seg.name || "self" == seg.name {
-                        try!(write!(w, "{}::", seg.name));
+                        write!(w, "{}::", seg.name)?;
                     } else {
                         root.push_str(&seg.name);
                         root.push_str("/");
-                        try!(write!(w, "<a class='mod'
+                        write!(w, "<a class='mod'
                                             href='{}index.html'>{}</a>::",
                                       root,
-                                      seg.name));
+                                      seg.name)?;
                     }
                 }
             }
             None => {
                 for seg in &path.segments[..amt] {
-                    try!(write!(w, "{}::", seg.name));
+                    write!(w, "{}::", seg.name)?;
                 }
             }
         }
@@ -360,12 +360,12 @@ fn resolved_path(w: &mut fmt::Formatter, did: DefId, path: &clean::Path,
 
     match href(did) {
         Some((url, shortty, fqp)) => {
-            try!(write!(w, "<a class='{}' href='{}' title='{}'>{}</a>",
-                          shortty, url, fqp.join("::"), last.name));
+            write!(w, "<a class='{}' href='{}' title='{}'>{}</a>",
+                          shortty, url, fqp.join("::"), last.name)?;
         }
-        _ => try!(write!(w, "{}", last.name)),
+        _ => write!(w, "{}", last.name)?,
     }
-    try!(write!(w, "{}", last.params));
+    write!(w, "{}", last.params)?;
     Ok(())
 }
 
@@ -378,9 +378,9 @@ fn primitive_link(f: &mut fmt::Formatter,
         Some(&LOCAL_CRATE) => {
             let len = CURRENT_LOCATION_KEY.with(|s| s.borrow().len());
             let len = if len == 0 {0} else {len - 1};
-            try!(write!(f, "<a class='primitive' href='{}primitive.{}.html'>",
+            write!(f, "<a class='primitive' href='{}primitive.{}.html'>",
                         repeat("../").take(len).collect::<String>(),
-                        prim.to_url_str()));
+                        prim.to_url_str())?;
             needs_termination = true;
         }
         Some(&cnum) => {
@@ -398,10 +398,10 @@ fn primitive_link(f: &mut fmt::Formatter,
             };
             match loc {
                 Some(root) => {
-                    try!(write!(f, "<a class='primitive' href='{}{}/primitive.{}.html'>",
+                    write!(f, "<a class='primitive' href='{}{}/primitive.{}.html'>",
                                 root,
                                 path.0.first().unwrap(),
-                                prim.to_url_str()));
+                                prim.to_url_str())?;
                     needs_termination = true;
                 }
                 None => {}
@@ -409,9 +409,9 @@ fn primitive_link(f: &mut fmt::Formatter,
         }
         None => {}
     }
-    try!(write!(f, "{}", name));
+    write!(f, "{}", name)?;
     if needs_termination {
-        try!(write!(f, "</a>"));
+        write!(f, "</a>")?;
     }
     Ok(())
 }
@@ -422,8 +422,8 @@ fn tybounds(w: &mut fmt::Formatter,
     match *typarams {
         Some(ref params) => {
             for param in params {
-                try!(write!(w, " + "));
-                try!(write!(w, "{}", *param));
+                write!(w, " + ")?;
+                write!(w, "{}", *param)?;
             }
             Ok(())
         }
@@ -439,7 +439,7 @@ impl fmt::Display for clean::Type {
             }
             clean::ResolvedPath{ did, ref typarams, ref path, is_generic } => {
                 // Paths like T::Output and Self::Output should be rendered with all segments
-                try!(resolved_path(f, did, path, is_generic));
+                resolved_path(f, did, path, is_generic)?;
                 tybounds(f, typarams)
             }
             clean::Infer => write!(f, "_"),
@@ -459,25 +459,25 @@ impl fmt::Display for clean::Type {
                 match &**typs {
                     [] => primitive_link(f, clean::PrimitiveTuple, "()"),
                     [ref one] => {
-                        try!(primitive_link(f, clean::PrimitiveTuple, "("));
-                        try!(write!(f, "{},", one));
+                        primitive_link(f, clean::PrimitiveTuple, "(")?;
+                        write!(f, "{},", one)?;
                         primitive_link(f, clean::PrimitiveTuple, ")")
                     }
                     many => {
-                        try!(primitive_link(f, clean::PrimitiveTuple, "("));
-                        try!(write!(f, "{}", CommaSep(&many)));
+                        primitive_link(f, clean::PrimitiveTuple, "(")?;
+                        write!(f, "{}", CommaSep(&many))?;
                         primitive_link(f, clean::PrimitiveTuple, ")")
                     }
                 }
             }
             clean::Vector(ref t) => {
-                try!(primitive_link(f, clean::Slice, &format!("[")));
-                try!(write!(f, "{}", t));
+                primitive_link(f, clean::Slice, &format!("["))?;
+                write!(f, "{}", t)?;
                 primitive_link(f, clean::Slice, &format!("]"))
             }
             clean::FixedVector(ref t, ref s) => {
-                try!(primitive_link(f, clean::PrimitiveType::Array, "["));
-                try!(write!(f, "{}", t));
+                primitive_link(f, clean::PrimitiveType::Array, "[")?;
+                write!(f, "{}", t)?;
                 primitive_link(f, clean::PrimitiveType::Array,
                                &format!("; {}]", *s))
             }
@@ -489,8 +489,8 @@ impl fmt::Display for clean::Type {
                                        &format!("*{}{}", RawMutableSpace(m), t))
                     }
                     _ => {
-                        try!(primitive_link(f, clean::PrimitiveType::PrimitiveRawPointer,
-                                            &format!("*{}", RawMutableSpace(m))));
+                        primitive_link(f, clean::PrimitiveType::PrimitiveRawPointer,
+                                            &format!("*{}", RawMutableSpace(m)))?;
                         write!(f, "{}", t)
                     }
                 }
@@ -508,9 +508,9 @@ impl fmt::Display for clean::Type {
                                 primitive_link(f, clean::Slice,
                                     &format!("&amp;{}{}[{}]", lt, m, **bt)),
                             _ => {
-                                try!(primitive_link(f, clean::Slice,
-                                    &format!("&amp;{}{}[", lt, m)));
-                                try!(write!(f, "{}", **bt));
+                                primitive_link(f, clean::Slice,
+                                    &format!("&amp;{}{}[", lt, m))?;
+                                write!(f, "{}", **bt)?;
                                 primitive_link(f, clean::Slice, "]")
                             }
                         }
@@ -523,9 +523,9 @@ impl fmt::Display for clean::Type {
             clean::PolyTraitRef(ref bounds) => {
                 for (i, bound) in bounds.iter().enumerate() {
                     if i != 0 {
-                        try!(write!(f, " + "));
+                        write!(f, " + ")?;
                     }
-                    try!(write!(f, "{}", *bound));
+                    write!(f, "{}", *bound)?;
                 }
                 Ok(())
             }
@@ -544,9 +544,9 @@ impl fmt::Display for clean::Type {
                 ref self_type,
                 trait_: box clean::ResolvedPath { did, ref typarams, .. },
             } => {
-                try!(write!(f, "{}::", self_type));
+                write!(f, "{}::", self_type)?;
                 let path = clean::Path::singleton(name.clone());
-                try!(resolved_path(f, did, &path, false));
+                resolved_path(f, did, &path, false)?;
 
                 // FIXME: `typarams` are not rendered, and this seems bad?
                 drop(typarams);
@@ -564,13 +564,13 @@ impl fmt::Display for clean::Type {
 
 impl fmt::Display for clean::Impl {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(f, "impl{} ", self.generics));
+        write!(f, "impl{} ", self.generics)?;
         if let Some(ref ty) = self.trait_ {
-            try!(write!(f, "{}{} for ",
+            write!(f, "{}{} for ",
                         if self.polarity == Some(clean::ImplPolarity::Negative) { "!" } else { "" },
-                        *ty));
+                        *ty)?;
         }
-        try!(write!(f, "{}{}", self.for_, WhereClause(&self.generics)));
+        write!(f, "{}{}", self.for_, WhereClause(&self.generics))?;
         Ok(())
     }
 }
@@ -578,11 +578,11 @@ impl fmt::Display for clean::Impl {
 impl fmt::Display for clean::Arguments {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         for (i, input) in self.values.iter().enumerate() {
-            if i > 0 { try!(write!(f, ", ")); }
+            if i > 0 { write!(f, ", ")?; }
             if !input.name.is_empty() {
-                try!(write!(f, "{}: ", input.name));
+                write!(f, "{}: ", input.name)?;
             }
-            try!(write!(f, "{}", input.type_));
+            write!(f, "{}", input.type_)?;
         }
         Ok(())
     }
@@ -678,12 +678,12 @@ impl fmt::Display for clean::Import {
                 write!(f, "use {}::*;", *src)
             }
             clean::ImportList(ref src, ref names) => {
-                try!(write!(f, "use {}::{{", *src));
+                write!(f, "use {}::{{", *src)?;
                 for (i, n) in names.iter().enumerate() {
                     if i > 0 {
-                        try!(write!(f, ", "));
+                        write!(f, ", ")?;
                     }
-                    try!(write!(f, "{}", *n));
+                    write!(f, "{}", *n)?;
                 }
                 write!(f, "}};")
             }
@@ -698,9 +698,9 @@ impl fmt::Display for clean::ImportSource {
             _ => {
                 for (i, seg) in self.path.segments.iter().enumerate() {
                     if i > 0 {
-                        try!(write!(f, "::"))
+                        write!(f, "::")?
                     }
-                    try!(write!(f, "{}", seg.name));
+                    write!(f, "{}", seg.name)?;
                 }
                 Ok(())
             }
@@ -713,13 +713,13 @@ impl fmt::Display for clean::ViewListIdent {
         match self.source {
             Some(did) => {
                 let path = clean::Path::singleton(self.name.clone());
-                try!(resolved_path(f, did, &path, false));
+                resolved_path(f, did, &path, false)?;
             }
-            _ => try!(write!(f, "{}", self.name)),
+            _ => write!(f, "{}", self.name)?,
         }
 
         if let Some(ref name) = self.rename {
-            try!(write!(f, " as {}", name));
+            write!(f, " as {}", name)?;
         }
         Ok(())
     }

src/librustdoc/html/highlight.rs

@@ -48,12 +48,12 @@ fn doit(sess: &parse::ParseSess, mut lexer: lexer::StringReader,
         out: &mut Write) -> io::Result<()> {
     use syntax::parse::lexer::Reader;
 
-    try!(write!(out, "<pre "));
+    write!(out, "<pre ")?;
     match id {
-        Some(id) => try!(write!(out, "id='{}' ", id)),
+        Some(id) => write!(out, "id='{}' ", id)?,
         None => {}
     }
-    try!(write!(out, "class='rust {}'>\n", class.unwrap_or("")));
+    write!(out, "class='rust {}'>\n", class.unwrap_or(""))?;
     let mut is_attribute = false;
     let mut is_macro = false;
     let mut is_macro_nonterminal = false;
@@ -66,16 +66,16 @@ fn doit(sess: &parse::ParseSess, mut lexer: lexer::StringReader,
 
         let klass = match next.tok {
             token::Whitespace => {
-                try!(write!(out, "{}", Escape(&snip(next.sp))));
+                write!(out, "{}", Escape(&snip(next.sp)))?;
                 continue
             },
             token::Comment => {
-                try!(write!(out, "<span class='comment'>{}</span>",
-                            Escape(&snip(next.sp))));
+                write!(out, "<span class='comment'>{}</span>",
+                            Escape(&snip(next.sp)))?;
                 continue
             },
             token::Shebang(s) => {
-                try!(write!(out, "{}", Escape(&s.as_str())));
+                write!(out, "{}", Escape(&s.as_str()))?;
                 continue
             },
             // If this '&' token is directly adjacent to another token, assume
@@ -114,13 +114,13 @@ fn doit(sess: &parse::ParseSess, mut lexer: lexer::StringReader,
             // span when we see the ']'.
             token::Pound => {
                 is_attribute = true;
-                try!(write!(out, r"<span class='attribute'>#"));
+                write!(out, r"<span class='attribute'>#")?;
                 continue
             }
             token::CloseDelim(token::Bracket) => {
                 if is_attribute {
                     is_attribute = false;
-                    try!(write!(out, "]</span>"));
+                    write!(out, "]</span>")?;
                     continue
                 } else {
                     ""
@@ -178,10 +178,10 @@ fn doit(sess: &parse::ParseSess, mut lexer: lexer::StringReader,
         // stringifying this token
         let snip = sess.codemap().span_to_snippet(next.sp).unwrap();
         if klass == "" {
-            try!(write!(out, "{}", Escape(&snip)));
+            write!(out, "{}", Escape(&snip))?;
         } else {
-            try!(write!(out, "<span class='{}'>{}</span>", klass,
-                          Escape(&snip)));
+            write!(out, "<span class='{}'>{}</span>", klass,
+                          Escape(&snip))?;
         }
     }
 

src/librustdoc/html/toc.rs

@@ -183,15 +183,15 @@ impl fmt::Debug for Toc {
 
 impl fmt::Display for Toc {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(fmt, "<ul>"));
+        write!(fmt, "<ul>")?;
         for entry in &self.entries {
             // recursively format this table of contents (the
             // `{children}` is the key).
-            try!(write!(fmt,
+            write!(fmt,
                         "\n<li><a href=\"#{id}\">{num} {name}</a>{children}</li>",
                         id = entry.id,
                         num = entry.sec_number, name = entry.name,
-                        children = entry.children))
+                        children = entry.children)?
         }
         write!(fmt, "</ul>")
     }

src/librustdoc/lib.rs

@@ -332,10 +332,10 @@ fn parse_externs(matches: &getopts::Matches) -> Result<core::Externs, String> {
     let mut externs = HashMap::new();
     for arg in &matches.opt_strs("extern") {
         let mut parts = arg.splitn(2, '=');
-        let name = try!(parts.next().ok_or("--extern value must not be empty".to_string()));
-        let location = try!(parts.next()
+        let name = parts.next().ok_or("--extern value must not be empty".to_string())?;
+        let location = parts.next()
                                  .ok_or("--extern value must be of the format `foo=bar`"
-                                    .to_string()));
+                                    .to_string())?;
         let name = name.to_string();
         externs.entry(name).or_insert(vec![]).push(location.to_string());
     }
@@ -502,6 +502,6 @@ fn json_output(krate: clean::Crate, res: Vec<plugins::PluginJson> ,
     json.insert("crate".to_string(), crate_json);
     json.insert("plugins".to_string(), Json::Object(plugins_json));
 
-    let mut file = try!(File::create(&dst));
+    let mut file = File::create(&dst)?;
     write!(&mut file, "{}", Json::Object(json))
 }

src/libserialize/collection_impls.rs

@@ -23,7 +23,7 @@ impl<
     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
         s.emit_seq(self.len(), |s| {
             for (i, e) in self.iter().enumerate() {
-                try!(s.emit_seq_elt(i, |s| e.encode(s)));
+                s.emit_seq_elt(i, |s| e.encode(s))?;
             }
             Ok(())
         })
@@ -35,7 +35,7 @@ impl<T:Decodable> Decodable for LinkedList<T> {
         d.read_seq(|d, len| {
             let mut list = LinkedList::new();
             for i in 0..len {
-                list.push_back(try!(d.read_seq_elt(i, |d| Decodable::decode(d))));
+                list.push_back(d.read_seq_elt(i, |d| Decodable::decode(d))?);
             }
             Ok(list)
         })
@@ -46,7 +46,7 @@ impl<T: Encodable> Encodable for VecDeque<T> {
     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
         s.emit_seq(self.len(), |s| {
             for (i, e) in self.iter().enumerate() {
-                try!(s.emit_seq_elt(i, |s| e.encode(s)));
+                s.emit_seq_elt(i, |s| e.encode(s))?;
             }
             Ok(())
         })
@@ -58,7 +58,7 @@ impl<T:Decodable> Decodable for VecDeque<T> {
         d.read_seq(|d, len| {
             let mut deque: VecDeque<T> = VecDeque::new();
             for i in 0..len {
-                deque.push_back(try!(d.read_seq_elt(i, |d| Decodable::decode(d))));
+                deque.push_back(d.read_seq_elt(i, |d| Decodable::decode(d))?);
             }
             Ok(deque)
         })
@@ -73,8 +73,8 @@ impl<
         e.emit_map(self.len(), |e| {
             let mut i = 0;
             for (key, val) in self {
-                try!(e.emit_map_elt_key(i, |e| key.encode(e)));
-                try!(e.emit_map_elt_val(i, |e| val.encode(e)));
+                e.emit_map_elt_key(i, |e| key.encode(e))?;
+                e.emit_map_elt_val(i, |e| val.encode(e))?;
                 i += 1;
             }
             Ok(())
@@ -90,8 +90,8 @@ impl<
         d.read_map(|d, len| {
             let mut map = BTreeMap::new();
             for i in 0..len {
-                let key = try!(d.read_map_elt_key(i, |d| Decodable::decode(d)));
-                let val = try!(d.read_map_elt_val(i, |d| Decodable::decode(d)));
+                let key = d.read_map_elt_key(i, |d| Decodable::decode(d))?;
+                let val = d.read_map_elt_val(i, |d| Decodable::decode(d))?;
                 map.insert(key, val);
             }
             Ok(map)
@@ -106,7 +106,7 @@ impl<
         s.emit_seq(self.len(), |s| {
             let mut i = 0;
             for e in self {
-                try!(s.emit_seq_elt(i, |s| e.encode(s)));
+                s.emit_seq_elt(i, |s| e.encode(s))?;
                 i += 1;
             }
             Ok(())
@@ -121,7 +121,7 @@ impl<
         d.read_seq(|d, len| {
             let mut set = BTreeSet::new();
             for i in 0..len {
-                set.insert(try!(d.read_seq_elt(i, |d| Decodable::decode(d))));
+                set.insert(d.read_seq_elt(i, |d| Decodable::decode(d))?);
             }
             Ok(set)
         })
@@ -144,7 +144,7 @@ impl<
     T: Decodable + CLike
 > Decodable for EnumSet<T> {
     fn decode<D: Decoder>(d: &mut D) -> Result<EnumSet<T>, D::Error> {
-        let bits = try!(d.read_uint());
+        let bits = d.read_uint()?;
         let mut set = EnumSet::new();
         for bit in 0..(mem::size_of::<usize>()*8) {
             if bits & (1 << bit) != 0 {
@@ -164,8 +164,8 @@ impl<K, V, S> Encodable for HashMap<K, V, S>
         e.emit_map(self.len(), |e| {
             let mut i = 0;
             for (key, val) in self {
-                try!(e.emit_map_elt_key(i, |e| key.encode(e)));
-                try!(e.emit_map_elt_val(i, |e| val.encode(e)));
+                e.emit_map_elt_key(i, |e| key.encode(e))?;
+                e.emit_map_elt_val(i, |e| val.encode(e))?;
                 i += 1;
             }
             Ok(())
@@ -183,8 +183,8 @@ impl<K, V, S> Decodable for HashMap<K, V, S>
             let state = Default::default();
             let mut map = HashMap::with_capacity_and_hasher(len, state);
             for i in 0..len {
-                let key = try!(d.read_map_elt_key(i, |d| Decodable::decode(d)));
-                let val = try!(d.read_map_elt_val(i, |d| Decodable::decode(d)));
+                let key = d.read_map_elt_key(i, |d| Decodable::decode(d))?;
+                let val = d.read_map_elt_val(i, |d| Decodable::decode(d))?;
                 map.insert(key, val);
             }
             Ok(map)
@@ -200,7 +200,7 @@ impl<T, S> Encodable for HashSet<T, S>
         s.emit_seq(self.len(), |s| {
             let mut i = 0;
             for e in self {
-                try!(s.emit_seq_elt(i, |s| e.encode(s)));
+                s.emit_seq_elt(i, |s| e.encode(s))?;
                 i += 1;
             }
             Ok(())
@@ -217,7 +217,7 @@ impl<T, S> Decodable for HashSet<T, S>
             let state = Default::default();
             let mut set = HashSet::with_capacity_and_hasher(len, state);
             for i in 0..len {
-                set.insert(try!(d.read_seq_elt(i, |d| Decodable::decode(d))));
+                set.insert(d.read_seq_elt(i, |d| Decodable::decode(d))?);
             }
             Ok(set)
         })

src/libserialize/json.rs

@@ -319,7 +319,7 @@ pub fn encode<T: ::Encodable>(object: &T) -> Result<string::String, EncoderError
     let mut s = String::new();
     {
         let mut encoder = Encoder::new(&mut s);
-        try!(object.encode(&mut encoder));
+        object.encode(&mut encoder)?;
     }
     Ok(s)
 }
@@ -371,7 +371,7 @@ pub type EncodeResult = Result<(), EncoderError>;
 pub type DecodeResult<T> = Result<T, DecoderError>;
 
 fn escape_str(wr: &mut fmt::Write, v: &str) -> EncodeResult {
-    try!(wr.write_str("\""));
+    wr.write_str("\"")?;
 
     let mut start = 0;
 
@@ -416,19 +416,19 @@ fn escape_str(wr: &mut fmt::Write, v: &str) -> EncodeResult {
         };
 
         if start < i {
-            try!(wr.write_str(&v[start..i]));
+            wr.write_str(&v[start..i])?;
         }
 
-        try!(wr.write_str(escaped));
+        wr.write_str(escaped)?;
 
         start = i + 1;
     }
 
     if start != v.len() {
-        try!(wr.write_str(&v[start..]));
+        wr.write_str(&v[start..])?;
     }
 
-    try!(wr.write_str("\""));
+    wr.write_str("\"")?;
     Ok(())
 }
 
@@ -442,12 +442,12 @@ fn spaces(wr: &mut fmt::Write, mut n: usize) -> EncodeResult {
     const BUF: &'static str = "                ";
 
     while n >= BUF.len() {
-        try!(wr.write_str(BUF));
+        wr.write_str(BUF)?;
         n -= BUF.len();
     }
 
     if n > 0 {
-        try!(wr.write_str(&BUF[..n]));
+        wr.write_str(&BUF[..n])?;
     }
     Ok(())
 }
@@ -491,7 +491,7 @@ impl<'a> ::Encoder for Encoder<'a> {
 
     fn emit_nil(&mut self) -> EncodeResult {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
-        try!(write!(self.writer, "null"));
+        write!(self.writer, "null")?;
         Ok(())
     }
 
@@ -510,9 +510,9 @@ impl<'a> ::Encoder for Encoder<'a> {
     fn emit_bool(&mut self, v: bool) -> EncodeResult {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
         if v {
-            try!(write!(self.writer, "true"));
+            write!(self.writer, "true")?;
         } else {
-            try!(write!(self.writer, "false"));
+            write!(self.writer, "false")?;
         }
         Ok(())
     }
@@ -551,11 +551,11 @@ impl<'a> ::Encoder for Encoder<'a> {
             escape_str(self.writer, name)
         } else {
             if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
-            try!(write!(self.writer, "{{\"variant\":"));
-            try!(escape_str(self.writer, name));
-            try!(write!(self.writer, ",\"fields\":["));
-            try!(f(self));
-            try!(write!(self.writer, "]}}"));
+            write!(self.writer, "{{\"variant\":")?;
+            escape_str(self.writer, name)?;
+            write!(self.writer, ",\"fields\":[")?;
+            f(self)?;
+            write!(self.writer, "]}}")?;
             Ok(())
         }
     }
@@ -565,7 +565,7 @@ impl<'a> ::Encoder for Encoder<'a> {
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
         if idx != 0 {
-            try!(write!(self.writer, ","));
+            write!(self.writer, ",")?;
         }
         f(self)
     }
@@ -595,9 +595,9 @@ impl<'a> ::Encoder for Encoder<'a> {
         F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
-        try!(write!(self.writer, "{{"));
-        try!(f(self));
-        try!(write!(self.writer, "}}"));
+        write!(self.writer, "{{")?;
+        f(self)?;
+        write!(self.writer, "}}")?;
         Ok(())
     }
 
@@ -605,9 +605,9 @@ impl<'a> ::Encoder for Encoder<'a> {
         F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
-        if idx != 0 { try!(write!(self.writer, ",")); }
-        try!(escape_str(self.writer, name));
-        try!(write!(self.writer, ":"));
+        if idx != 0 { write!(self.writer, ",")?; }
+        escape_str(self.writer, name)?;
+        write!(self.writer, ":")?;
         f(self)
     }
 
@@ -658,9 +658,9 @@ impl<'a> ::Encoder for Encoder<'a> {
         F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
-        try!(write!(self.writer, "["));
-        try!(f(self));
-        try!(write!(self.writer, "]"));
+        write!(self.writer, "[")?;
+        f(self)?;
+        write!(self.writer, "]")?;
         Ok(())
     }
 
@@ -669,7 +669,7 @@ impl<'a> ::Encoder for Encoder<'a> {
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
         if idx != 0 {
-            try!(write!(self.writer, ","));
+            write!(self.writer, ",")?;
         }
         f(self)
     }
@@ -678,9 +678,9 @@ impl<'a> ::Encoder for Encoder<'a> {
         F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
-        try!(write!(self.writer, "{{"));
-        try!(f(self));
-        try!(write!(self.writer, "}}"));
+        write!(self.writer, "{{")?;
+        f(self)?;
+        write!(self.writer, "}}")?;
         Ok(())
     }
 
@@ -688,9 +688,9 @@ impl<'a> ::Encoder for Encoder<'a> {
         F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
-        if idx != 0 { try!(write!(self.writer, ",")) }
+        if idx != 0 { write!(self.writer, ",")? }
         self.is_emitting_map_key = true;
-        try!(f(self));
+        f(self)?;
         self.is_emitting_map_key = false;
         Ok(())
     }
@@ -699,7 +699,7 @@ impl<'a> ::Encoder for Encoder<'a> {
         F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
-        try!(write!(self.writer, ":"));
+        write!(self.writer, ":")?;
         f(self)
     }
 }
@@ -739,7 +739,7 @@ impl<'a> ::Encoder for PrettyEncoder<'a> {
 
     fn emit_nil(&mut self) -> EncodeResult {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
-        try!(write!(self.writer, "null"));
+        write!(self.writer, "null")?;
         Ok(())
     }
 
@@ -758,9 +758,9 @@ impl<'a> ::Encoder for PrettyEncoder<'a> {
     fn emit_bool(&mut self, v: bool) -> EncodeResult {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
         if v {
-            try!(write!(self.writer, "true"));
+            write!(self.writer, "true")?;
         } else {
-            try!(write!(self.writer, "false"));
+            write!(self.writer, "false")?;
         }
         Ok(())
     }
@@ -797,23 +797,23 @@ impl<'a> ::Encoder for PrettyEncoder<'a> {
             escape_str(self.writer, name)
         } else {
             if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
-            try!(write!(self.writer, "{{\n"));
+            write!(self.writer, "{{\n")?;
             self.curr_indent += self.indent;
-            try!(spaces(self.writer, self.curr_indent));
-            try!(write!(self.writer, "\"variant\": "));
-            try!(escape_str(self.writer, name));
-            try!(write!(self.writer, ",\n"));
-            try!(spaces(self.writer, self.curr_indent));
-            try!(write!(self.writer, "\"fields\": [\n"));
+            spaces(self.writer, self.curr_indent)?;
+            write!(self.writer, "\"variant\": ")?;
+            escape_str(self.writer, name)?;
+            write!(self.writer, ",\n")?;
+            spaces(self.writer, self.curr_indent)?;
+            write!(self.writer, "\"fields\": [\n")?;
             self.curr_indent += self.indent;
-            try!(f(self));
+            f(self)?;
             self.curr_indent -= self.indent;
-            try!(write!(self.writer, "\n"));
-            try!(spaces(self.writer, self.curr_indent));
+            write!(self.writer, "\n")?;
+            spaces(self.writer, self.curr_indent)?;
             self.curr_indent -= self.indent;
-            try!(write!(self.writer, "]\n"));
-            try!(spaces(self.writer, self.curr_indent));
-            try!(write!(self.writer, "}}"));
+            write!(self.writer, "]\n")?;
+            spaces(self.writer, self.curr_indent)?;
+            write!(self.writer, "}}")?;
             Ok(())
         }
     }
@@ -823,9 +823,9 @@ impl<'a> ::Encoder for PrettyEncoder<'a> {
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
         if idx != 0 {
-            try!(write!(self.writer, ",\n"));
+            write!(self.writer, ",\n")?;
         }
-        try!(spaces(self.writer, self.curr_indent));
+        spaces(self.writer, self.curr_indent)?;
         f(self)
     }
 
@@ -856,15 +856,15 @@ impl<'a> ::Encoder for PrettyEncoder<'a> {
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
         if len == 0 {
-            try!(write!(self.writer, "{{}}"));
+            write!(self.writer, "{{}}")?;
         } else {
-            try!(write!(self.writer, "{{"));
+            write!(self.writer, "{{")?;
             self.curr_indent += self.indent;
-            try!(f(self));
+            f(self)?;
             self.curr_indent -= self.indent;
-            try!(write!(self.writer, "\n"));
-            try!(spaces(self.writer, self.curr_indent));
-            try!(write!(self.writer, "}}"));
+            write!(self.writer, "\n")?;
+            spaces(self.writer, self.curr_indent)?;
+            write!(self.writer, "}}")?;
         }
         Ok(())
     }
@@ -874,13 +874,13 @@ impl<'a> ::Encoder for PrettyEncoder<'a> {
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
         if idx == 0 {
-            try!(write!(self.writer, "\n"));
+            write!(self.writer, "\n")?;
         } else {
-            try!(write!(self.writer, ",\n"));
+            write!(self.writer, ",\n")?;
         }
-        try!(spaces(self.writer, self.curr_indent));
-        try!(escape_str(self.writer, name));
-        try!(write!(self.writer, ": "));
+        spaces(self.writer, self.curr_indent)?;
+        escape_str(self.writer, name)?;
+        write!(self.writer, ": ")?;
         f(self)
     }
 
@@ -932,15 +932,15 @@ impl<'a> ::Encoder for PrettyEncoder<'a> {
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
         if len == 0 {
-            try!(write!(self.writer, "[]"));
+            write!(self.writer, "[]")?;
         } else {
-            try!(write!(self.writer, "["));
+            write!(self.writer, "[")?;
             self.curr_indent += self.indent;
-            try!(f(self));
+            f(self)?;
             self.curr_indent -= self.indent;
-            try!(write!(self.writer, "\n"));
-            try!(spaces(self.writer, self.curr_indent));
-            try!(write!(self.writer, "]"));
+            write!(self.writer, "\n")?;
+            spaces(self.writer, self.curr_indent)?;
+            write!(self.writer, "]")?;
         }
         Ok(())
     }
@@ -950,11 +950,11 @@ impl<'a> ::Encoder for PrettyEncoder<'a> {
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
         if idx == 0 {
-            try!(write!(self.writer, "\n"));
+            write!(self.writer, "\n")?;
         } else {
-            try!(write!(self.writer, ",\n"));
+            write!(self.writer, ",\n")?;
         }
-        try!(spaces(self.writer, self.curr_indent));
+        spaces(self.writer, self.curr_indent)?;
         f(self)
     }
 
@@ -963,15 +963,15 @@ impl<'a> ::Encoder for PrettyEncoder<'a> {
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
         if len == 0 {
-            try!(write!(self.writer, "{{}}"));
+            write!(self.writer, "{{}}")?;
         } else {
-            try!(write!(self.writer, "{{"));
+            write!(self.writer, "{{")?;
             self.curr_indent += self.indent;
-            try!(f(self));
+            f(self)?;
             self.curr_indent -= self.indent;
-            try!(write!(self.writer, "\n"));
-            try!(spaces(self.writer, self.curr_indent));
-            try!(write!(self.writer, "}}"));
+            write!(self.writer, "\n")?;
+            spaces(self.writer, self.curr_indent)?;
+            write!(self.writer, "}}")?;
         }
         Ok(())
     }
@@ -981,13 +981,13 @@ impl<'a> ::Encoder for PrettyEncoder<'a> {
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
         if idx == 0 {
-            try!(write!(self.writer, "\n"));
+            write!(self.writer, "\n")?;
         } else {
-            try!(write!(self.writer, ",\n"));
+            write!(self.writer, ",\n")?;
         }
-        try!(spaces(self.writer, self.curr_indent));
+        spaces(self.writer, self.curr_indent)?;
         self.is_emitting_map_key = true;
-        try!(f(self));
+        f(self)?;
         self.is_emitting_map_key = false;
         Ok(())
     }
@@ -996,7 +996,7 @@ impl<'a> ::Encoder for PrettyEncoder<'a> {
         F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
     {
         if self.is_emitting_map_key { return Err(EncoderError::BadHashmapKey); }
-        try!(write!(self.writer, ": "));
+        write!(self.writer, ": ")?;
         f(self)
     }
 }
@@ -1695,7 +1695,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
                     'n' => res.push('\n'),
                     'r' => res.push('\r'),
                     't' => res.push('\t'),
-                    'u' => match try!(self.decode_hex_escape()) {
+                    'u' => match self.decode_hex_escape()? {
                         0xDC00 ... 0xDFFF => {
                             return self.error(LoneLeadingSurrogateInHexEscape)
                         }
@@ -1708,7 +1708,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
                                 _ => return self.error(UnexpectedEndOfHexEscape),
                             }
 
-                            let n2 = try!(self.decode_hex_escape());
+                            let n2 = self.decode_hex_escape()?;
                             if n2 < 0xDC00 || n2 > 0xDFFF {
                                 return self.error(LoneLeadingSurrogateInHexEscape)
                             }
@@ -2174,7 +2174,7 @@ impl ::Decoder for Decoder {
     }
 
     fn read_char(&mut self) -> DecodeResult<char> {
-        let s = try!(self.read_str());
+        let s = self.read_str()?;
         {
             let mut it = s.chars();
             match (it.next(), it.next()) {
@@ -2264,7 +2264,7 @@ impl ::Decoder for Decoder {
     fn read_struct<T, F>(&mut self, _name: &str, _len: usize, f: F) -> DecodeResult<T> where
         F: FnOnce(&mut Decoder) -> DecodeResult<T>,
     {
-        let value = try!(f(self));
+        let value = f(self)?;
         self.pop();
         Ok(value)
     }
@@ -2276,7 +2276,7 @@ impl ::Decoder for Decoder {
                                -> DecodeResult<T> where
         F: FnOnce(&mut Decoder) -> DecodeResult<T>,
     {
-        let mut obj = try!(expect!(self.pop(), Object));
+        let mut obj = expect!(self.pop(), Object)?;
 
         let value = match obj.remove(&name.to_string()) {
             None => {
@@ -2290,7 +2290,7 @@ impl ::Decoder for Decoder {
             },
             Some(json) => {
                 self.stack.push(json);
-                try!(f(self))
+                f(self)?
             }
         };
         self.stack.push(Json::Object(obj));
@@ -2346,7 +2346,7 @@ impl ::Decoder for Decoder {
     fn read_seq<T, F>(&mut self, f: F) -> DecodeResult<T> where
         F: FnOnce(&mut Decoder, usize) -> DecodeResult<T>,
     {
-        let array = try!(expect!(self.pop(), Array));
+        let array = expect!(self.pop(), Array)?;
         let len = array.len();
         for v in array.into_iter().rev() {
             self.stack.push(v);
@@ -2363,7 +2363,7 @@ impl ::Decoder for Decoder {
     fn read_map<T, F>(&mut self, f: F) -> DecodeResult<T> where
         F: FnOnce(&mut Decoder, usize) -> DecodeResult<T>,
     {
-        let obj = try!(expect!(self.pop(), Object));
+        let obj = expect!(self.pop(), Object)?;
         let len = obj.len();
         for (key, value) in obj {
             self.stack.push(value);

src/libserialize/serialize.rs

@@ -410,13 +410,13 @@ impl<T: ?Sized + Encodable> Encodable for Box<T> {
 
 impl< T: Decodable> Decodable for Box<T> {
     fn decode<D: Decoder>(d: &mut D) -> Result<Box<T>, D::Error> {
-        Ok(box try!(Decodable::decode(d)))
+        Ok(box Decodable::decode(d)?)
     }
 }
 
 impl< T: Decodable> Decodable for Box<[T]> {
     fn decode<D: Decoder>(d: &mut D) -> Result<Box<[T]>, D::Error> {
-        let v: Vec<T> = try!(Decodable::decode(d));
+        let v: Vec<T> = Decodable::decode(d)?;
         Ok(v.into_boxed_slice())
     }
 }
@@ -431,7 +431,7 @@ impl<T:Encodable> Encodable for Rc<T> {
 impl<T:Decodable> Decodable for Rc<T> {
     #[inline]
     fn decode<D: Decoder>(d: &mut D) -> Result<Rc<T>, D::Error> {
-        Ok(Rc::new(try!(Decodable::decode(d))))
+        Ok(Rc::new(Decodable::decode(d)?))
     }
 }
 
@@ -439,7 +439,7 @@ impl<T:Encodable> Encodable for [T] {
     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
         s.emit_seq(self.len(), |s| {
             for (i, e) in self.iter().enumerate() {
-                try!(s.emit_seq_elt(i, |s| e.encode(s)))
+                s.emit_seq_elt(i, |s| e.encode(s))?
             }
             Ok(())
         })
@@ -450,7 +450,7 @@ impl<T:Encodable> Encodable for Vec<T> {
     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
         s.emit_seq(self.len(), |s| {
             for (i, e) in self.iter().enumerate() {
-                try!(s.emit_seq_elt(i, |s| e.encode(s)))
+                s.emit_seq_elt(i, |s| e.encode(s))?
             }
             Ok(())
         })
@@ -462,7 +462,7 @@ impl<T:Decodable> Decodable for Vec<T> {
         d.read_seq(|d, len| {
             let mut v = Vec::with_capacity(len);
             for i in 0..len {
-                v.push(try!(d.read_seq_elt(i, |d| Decodable::decode(d))));
+                v.push(d.read_seq_elt(i, |d| Decodable::decode(d))?);
             }
             Ok(v)
         })
@@ -484,7 +484,7 @@ impl<T:Decodable> Decodable for Option<T> {
     fn decode<D: Decoder>(d: &mut D) -> Result<Option<T>, D::Error> {
         d.read_option(|d, b| {
             if b {
-                Ok(Some(try!(Decodable::decode(d))))
+                Ok(Some(Decodable::decode(d)?))
             } else {
                 Ok(None)
             }
@@ -546,7 +546,7 @@ impl Encodable for path::PathBuf {
 
 impl Decodable for path::PathBuf {
     fn decode<D: Decoder>(d: &mut D) -> Result<path::PathBuf, D::Error> {
-        let bytes: String = try!(Decodable::decode(d));
+        let bytes: String = Decodable::decode(d)?;
         Ok(path::PathBuf::from(bytes))
     }
 }
@@ -559,7 +559,7 @@ impl<T: Encodable + Copy> Encodable for Cell<T> {
 
 impl<T: Decodable + Copy> Decodable for Cell<T> {
     fn decode<D: Decoder>(d: &mut D) -> Result<Cell<T>, D::Error> {
-        Ok(Cell::new(try!(Decodable::decode(d))))
+        Ok(Cell::new(Decodable::decode(d)?))
     }
 }
 
@@ -576,7 +576,7 @@ impl<T: Encodable> Encodable for RefCell<T> {
 
 impl<T: Decodable> Decodable for RefCell<T> {
     fn decode<D: Decoder>(d: &mut D) -> Result<RefCell<T>, D::Error> {
-        Ok(RefCell::new(try!(Decodable::decode(d))))
+        Ok(RefCell::new(Decodable::decode(d)?))
     }
 }
 
@@ -588,7 +588,7 @@ impl<T:Encodable> Encodable for Arc<T> {
 
 impl<T:Decodable+Send+Sync> Decodable for Arc<T> {
     fn decode<D: Decoder>(d: &mut D) -> Result<Arc<T>, D::Error> {
-        Ok(Arc::new(try!(Decodable::decode(d))))
+        Ok(Arc::new(Decodable::decode(d)?))
     }
 }
 
@@ -607,9 +607,9 @@ impl<S:Encoder> EncoderHelpers for S {
     {
         self.emit_seq(v.len(), |this| {
             for (i, e) in v.iter().enumerate() {
-                try!(this.emit_seq_elt(i, |this| {
+                this.emit_seq_elt(i, |this| {
                     f(this, e)
-                }));
+                })?;
             }
             Ok(())
         })
@@ -629,7 +629,7 @@ impl<D: Decoder> DecoderHelpers for D {
         self.read_seq(|this, len| {
             let mut v = Vec::with_capacity(len);
             for i in 0..len {
-                v.push(try!(this.read_seq_elt(i, |this| f(this))));
+                v.push(this.read_seq_elt(i, |this| f(this))?);
             }
             Ok(v)
         })

src/libstd/ffi/c_str.rs

@@ -318,9 +318,9 @@ impl From<CString> for Vec<u8> {
 #[stable(feature = "cstr_debug", since = "1.3.0")]
 impl fmt::Debug for CStr {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(f, "\""));
+        write!(f, "\"")?;
         for byte in self.to_bytes().iter().flat_map(|&b| ascii::escape_default(b)) {
-            try!(f.write_char(byte as char));
+            f.write_char(byte as char)?;
         }
         write!(f, "\"")
     }

src/libstd/fs.rs

@@ -305,7 +305,7 @@ impl File {
     #[unstable(feature = "file_try_clone", reason = "newly added", issue = "31405")]
     pub fn try_clone(&self) -> io::Result<File> {
         Ok(File {
-            inner: try!(self.inner.duplicate())
+            inner: self.inner.duplicate()?
         })
     }
 }
@@ -565,7 +565,7 @@ impl OpenOptions {
     }
 
     fn _open(&self, path: &Path) -> io::Result<File> {
-        let inner = try!(fs_imp::File::open(path, &self.0));
+        let inner = fs_imp::File::open(path, &self.0)?;
         Ok(File { inner: inner })
     }
 }
@@ -1440,7 +1440,7 @@ impl DirBuilder {
     fn create_dir_all(&self, path: &Path) -> io::Result<()> {
         if path == Path::new("") || path.is_dir() { return Ok(()) }
         if let Some(p) = path.parent() {
-            try!(self.create_dir_all(p))
+            self.create_dir_all(p)?
         }
         self.inner.mkdir(path)
     }

src/libstd/io/buffered.rs

@@ -172,8 +172,8 @@ impl<R: Read> Read for BufReader<R> {
             return self.inner.read(buf);
         }
         let nread = {
-            let mut rem = try!(self.fill_buf());
-            try!(rem.read(buf))
+            let mut rem = self.fill_buf()?;
+            rem.read(buf)?
         };
         self.consume(nread);
         Ok(nread)
@@ -186,7 +186,7 @@ impl<R: Read> BufRead for BufReader<R> {
         // If we've reached the end of our internal buffer then we need to fetch
         // some more data from the underlying reader.
         if self.pos == self.cap {
-            self.cap = try!(self.inner.read(&mut self.buf));
+            self.cap = self.inner.read(&mut self.buf)?;
             self.pos = 0;
         }
         Ok(&self.buf[self.pos..self.cap])
@@ -237,16 +237,16 @@ impl<R: Seek> Seek for BufReader<R> {
             // support seeking by i64::min_value() so we need to handle underflow when subtracting
             // remainder.
             if let Some(offset) = n.checked_sub(remainder) {
-                result = try!(self.inner.seek(SeekFrom::Current(offset)));
+                result = self.inner.seek(SeekFrom::Current(offset))?;
             } else {
                 // seek backwards by our remainder, and then by the offset
-                try!(self.inner.seek(SeekFrom::Current(-remainder)));
+                self.inner.seek(SeekFrom::Current(-remainder))?;
                 self.pos = self.cap; // empty the buffer
-                result = try!(self.inner.seek(SeekFrom::Current(n)));
+                result = self.inner.seek(SeekFrom::Current(n))?;
             }
         } else {
             // Seeking with Start/End doesn't care about our buffer length.
-            result = try!(self.inner.seek(pos));
+            result = self.inner.seek(pos)?;
         }
         self.pos = self.cap; // empty the buffer
         Ok(result)
@@ -461,7 +461,7 @@ impl<W: Write> BufWriter<W> {
 impl<W: Write> Write for BufWriter<W> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         if self.buf.len() + buf.len() > self.buf.capacity() {
-            try!(self.flush_buf());
+            self.flush_buf()?;
         }
         if buf.len() >= self.buf.capacity() {
             self.panicked = true;
@@ -761,7 +761,7 @@ impl<W: Write> Write for LineWriter<W> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         match memchr::memrchr(b'\n', buf) {
             Some(i) => {
-                let n = try!(self.inner.write(&buf[..i + 1]));
+                let n = self.inner.write(&buf[..i + 1])?;
                 if n != i + 1 || self.inner.flush().is_err() {
                     // Do not return errors on partial writes.
                     return Ok(n);

src/libstd/io/cursor.rs

@@ -213,7 +213,7 @@ impl<T> io::Seek for Cursor<T> where T: AsRef<[u8]> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> Read for Cursor<T> where T: AsRef<[u8]> {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
-        let n = try!(Read::read(&mut try!(self.fill_buf()), buf));
+        let n = Read::read(&mut self.fill_buf()?, buf)?;
         self.pos += n as u64;
         Ok(n)
     }
@@ -232,7 +232,7 @@ impl<T> BufRead for Cursor<T> where T: AsRef<[u8]> {
 impl<'a> Write for Cursor<&'a mut [u8]> {
     fn write(&mut self, data: &[u8]) -> io::Result<usize> {
         let pos = cmp::min(self.pos, self.inner.len() as u64);
-        let amt = try!((&mut self.inner[(pos as usize)..]).write(data));
+        let amt = (&mut self.inner[(pos as usize)..]).write(data)?;
         self.pos += amt as u64;
         Ok(amt)
     }
@@ -271,7 +271,7 @@ impl Write for Cursor<Vec<u8>> {
 impl Write for Cursor<Box<[u8]>> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         let pos = cmp::min(self.pos, self.inner.len() as u64);
-        let amt = try!((&mut self.inner[(pos as usize)..]).write(buf));
+        let amt = (&mut self.inner[(pos as usize)..]).write(buf)?;
         self.pos += amt as u64;
         Ok(amt)
     }

src/libstd/io/impls.rs

@@ -196,7 +196,7 @@ impl<'a> Write for &'a mut [u8] {
 
     #[inline]
     fn write_all(&mut self, data: &[u8]) -> io::Result<()> {
-        if try!(self.write(data)) == data.len() {
+        if self.write(data)? == data.len() {
             Ok(())
         } else {
             Err(Error::new(ErrorKind::WriteZero, "failed to write whole buffer"))

src/libstd/io/mod.rs

@@ -1433,7 +1433,7 @@ pub struct Chain<T, U> {
 impl<T: Read, U: Read> Read for Chain<T, U> {
     fn read(&mut self, buf: &mut [u8]) -> Result<usize> {
         if !self.done_first {
-            match try!(self.first.read(buf)) {
+            match self.first.read(buf)? {
                 0 => { self.done_first = true; }
                 n => return Ok(n),
             }
@@ -1475,7 +1475,7 @@ impl<T: Read> Read for Take<T> {
         }
 
         let max = cmp::min(buf.len() as u64, self.limit) as usize;
-        let n = try!(self.inner.read(&mut buf[..max]));
+        let n = self.inner.read(&mut buf[..max])?;
         self.limit -= n as u64;
         Ok(n)
     }
@@ -1484,7 +1484,7 @@ impl<T: Read> Read for Take<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: BufRead> BufRead for Take<T> {
     fn fill_buf(&mut self) -> Result<&[u8]> {
-        let buf = try!(self.inner.fill_buf());
+        let buf = self.inner.fill_buf()?;
         let cap = cmp::min(buf.len() as u64, self.limit) as usize;
         Ok(&buf[..cap])
     }

src/libstd/io/util.rs

@@ -55,7 +55,7 @@ pub fn copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> io::Result<
             Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
             Err(e) => return Err(e),
         };
-        try!(writer.write_all(&buf[..len]));
+        writer.write_all(&buf[..len])?;
         written += len as u64;
     }
 }

src/libstd/net/addr.rs

@@ -431,13 +431,13 @@ impl ToSocketAddrs for (Ipv6Addr, u16) {
 }
 
 fn resolve_socket_addr(s: &str, p: u16) -> io::Result<vec::IntoIter<SocketAddr>> {
-    let ips = try!(lookup_host(s));
-    let v: Vec<_> = try!(ips.map(|a| {
+    let ips = lookup_host(s)?;
+    let v: Vec<_> = ips.map(|a| {
         a.map(|mut a| {
             a.set_port(p);
             a
         })
-    }).collect());
+    }).collect()?;
     Ok(v.into_iter())
 }
 

src/libstd/net/ip.rs

@@ -487,16 +487,16 @@ impl fmt::Display for Ipv6Addr {
                 if zeros_len > 1 {
                     fn fmt_subslice(segments: &[u16], fmt: &mut fmt::Formatter) -> fmt::Result {
                         if !segments.is_empty() {
-                            try!(write!(fmt, "{:x}", segments[0]));
+                            write!(fmt, "{:x}", segments[0])?;
                             for &seg in &segments[1..] {
-                                try!(write!(fmt, ":{:x}", seg));
+                                write!(fmt, ":{:x}", seg)?;
                             }
                         }
                         Ok(())
                     }
 
-                    try!(fmt_subslice(&self.segments()[..zeros_at], fmt));
-                    try!(fmt.write_str("::"));
+                    fmt_subslice(&self.segments()[..zeros_at], fmt)?;
+                    fmt.write_str("::")?;
                     fmt_subslice(&self.segments()[zeros_at + zeros_len..], fmt)
                 } else {
                     let &[a, b, c, d, e, f, g, h] = &self.segments();

src/libstd/net/mod.rs

@@ -74,7 +74,7 @@ fn each_addr<A: ToSocketAddrs, F, T>(addr: A, mut f: F) -> io::Result<T>
     where F: FnMut(&SocketAddr) -> io::Result<T>
 {
     let mut last_err = None;
-    for addr in try!(addr.to_socket_addrs()) {
+    for addr in addr.to_socket_addrs()? {
         match f(&addr) {
             Ok(l) => return Ok(l),
             Err(e) => last_err = Some(e),

src/libstd/net/udp.rs

@@ -70,7 +70,7 @@ impl UdpSocket {
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn send_to<A: ToSocketAddrs>(&self, buf: &[u8], addr: A)
                                      -> io::Result<usize> {
-        match try!(addr.to_socket_addrs()).next() {
+        match addr.to_socket_addrs()?.next() {
             Some(addr) => self.0.send_to(buf, &addr),
             None => Err(Error::new(ErrorKind::InvalidInput,
                                    "no addresses to send data to")),

src/libstd/panic.rs

@@ -315,7 +315,7 @@ pub fn recover<F: FnOnce() -> R + RecoverSafe, R>(f: F) -> Result<R> {
     let mut result = None;
     unsafe {
         let result = &mut result;
-        try!(unwind::try(move || *result = Some(f())))
+        unwind::try(move || *result = Some(f()))?
     }
     Ok(result.unwrap())
 }

src/libstd/process.rs

@@ -520,7 +520,7 @@ impl Child {
             }
         }
 
-        let status = try!(self.wait());
+        let status = self.wait()?;
         Ok(Output {
             status: status,
             stdout: stdout,

src/libstd/sync/mutex.rs

@@ -234,7 +234,7 @@ impl<T: ?Sized> Mutex<T> {
     pub fn try_lock(&self) -> TryLockResult<MutexGuard<T>> {
         unsafe {
             if self.inner.lock.try_lock() {
-                Ok(try!(MutexGuard::new(&*self.inner, &self.data)))
+                Ok(MutexGuard::new(&*self.inner, &self.data)?)
             } else {
                 Err(TryLockError::WouldBlock)
             }
@@ -353,7 +353,7 @@ impl StaticMutex {
     pub fn try_lock(&'static self) -> TryLockResult<MutexGuard<()>> {
         unsafe {
             if self.lock.try_lock() {
-                Ok(try!(MutexGuard::new(self, &DUMMY.0)))
+                Ok(MutexGuard::new(self, &DUMMY.0)?)
             } else {
                 Err(TryLockError::WouldBlock)
             }

src/libstd/sync/rwlock.rs

@@ -205,7 +205,7 @@ impl<T: ?Sized> RwLock<T> {
     pub fn try_read(&self) -> TryLockResult<RwLockReadGuard<T>> {
         unsafe {
             if self.inner.lock.try_read() {
-                Ok(try!(RwLockReadGuard::new(&*self.inner, &self.data)))
+                Ok(RwLockReadGuard::new(&*self.inner, &self.data)?)
             } else {
                 Err(TryLockError::WouldBlock)
             }
@@ -257,7 +257,7 @@ impl<T: ?Sized> RwLock<T> {
     pub fn try_write(&self) -> TryLockResult<RwLockWriteGuard<T>> {
         unsafe {
             if self.inner.lock.try_write() {
-                Ok(try!(RwLockWriteGuard::new(&*self.inner, &self.data)))
+                Ok(RwLockWriteGuard::new(&*self.inner, &self.data)?)
             } else {
                 Err(TryLockError::WouldBlock)
             }
@@ -382,7 +382,7 @@ impl StaticRwLock {
                     -> TryLockResult<RwLockReadGuard<'static, ()>> {
         unsafe {
             if self.lock.try_read(){
-                Ok(try!(RwLockReadGuard::new(self, &DUMMY.0)))
+                Ok(RwLockReadGuard::new(self, &DUMMY.0)?)
             } else {
                 Err(TryLockError::WouldBlock)
             }
@@ -409,7 +409,7 @@ impl StaticRwLock {
                      -> TryLockResult<RwLockWriteGuard<'static, ()>> {
         unsafe {
             if self.lock.try_write() {
-                Ok(try!(RwLockWriteGuard::new(self, &DUMMY.0)))
+                Ok(RwLockWriteGuard::new(self, &DUMMY.0)?)
             } else {
                 Err(TryLockError::WouldBlock)
             }

src/libstd/sys/common/backtrace.rs

@@ -46,10 +46,10 @@ pub fn log_enabled() -> bool {
 // These output functions should now be used everywhere to ensure consistency.
 pub fn output(w: &mut Write, idx: isize, addr: *mut libc::c_void,
               s: Option<&[u8]>) -> io::Result<()> {
-    try!(write!(w, "  {:2}: {:2$?} - ", idx, addr, HEX_WIDTH));
+    write!(w, "  {:2}: {:2$?} - ", idx, addr, HEX_WIDTH)?;
     match s.and_then(|s| str::from_utf8(s).ok()) {
-        Some(string) => try!(demangle(w, string)),
-        None => try!(write!(w, "<unknown>")),
+        Some(string) => demangle(w, string)?,
+        None => write!(w, "<unknown>")?,
     }
     w.write_all(&['\n' as u8])
 }
@@ -59,9 +59,9 @@ pub fn output_fileline(w: &mut Write, file: &[u8], line: libc::c_int,
                        more: bool) -> io::Result<()> {
     let file = str::from_utf8(file).unwrap_or("<unknown>");
     // prior line: "  ##: {:2$} - func"
-    try!(write!(w, "      {:3$}at {}:{}", "", file, line, HEX_WIDTH));
+    write!(w, "      {:3$}at {}:{}", "", file, line, HEX_WIDTH)?;
     if more {
-        try!(write!(w, " <... and possibly more>"));
+        write!(w, " <... and possibly more>")?;
     }
     w.write_all(&['\n' as u8])
 }
@@ -121,12 +121,12 @@ pub fn demangle(writer: &mut Write, s: &str) -> io::Result<()> {
 
     // Alright, let's do this.
     if !valid {
-        try!(writer.write_all(s.as_bytes()));
+        writer.write_all(s.as_bytes())?;
     } else {
         let mut first = true;
         while !inner.is_empty() {
             if !first {
-                try!(writer.write_all(b"::"));
+                writer.write_all(b"::")?;
             } else {
                 first = false;
             }
@@ -177,7 +177,7 @@ pub fn demangle(writer: &mut Write, s: &str) -> io::Result<()> {
                         None => rest.len(),
                         Some(i) => i,
                     };
-                    try!(writer.write_all(rest[..idx].as_bytes()));
+                    writer.write_all(rest[..idx].as_bytes())?;
                     rest = &rest[idx..];
                 }
             }

src/libstd/sys/common/gnu/libbacktrace.rs

@@ -172,9 +172,9 @@ pub fn print(w: &mut Write, idx: isize, addr: *mut libc::c_void,
                           data_addr as *mut libc::c_void)
     };
     if ret == 0 || data.is_null() {
-        try!(output(w, idx, addr, None));
+        output(w, idx, addr, None)?;
     } else {
-        try!(output(w, idx, addr, Some(unsafe { CStr::from_ptr(data).to_bytes() })));
+        output(w, idx, addr, Some(unsafe { CStr::from_ptr(data).to_bytes() }))?;
     }
 
     // pcinfo may return an arbitrary number of file:line pairs,
@@ -198,7 +198,7 @@ pub fn print(w: &mut Write, idx: isize, addr: *mut libc::c_void,
         for (i, &(file, line)) in fileline_buf[..fileline_count].iter().enumerate() {
             if file.is_null() { continue; } // just to be sure
             let file = unsafe { CStr::from_ptr(file).to_bytes() };
-            try!(output_fileline(w, file, line, i == FILELINE_SIZE - 1));
+            output_fileline(w, file, line, i == FILELINE_SIZE - 1)?;
         }
     }
 

src/libstd/sys/common/net.rs

@@ -48,8 +48,8 @@ pub fn setsockopt<T>(sock: &Socket, opt: c_int, val: c_int,
                      payload: T) -> io::Result<()> {
     unsafe {
         let payload = &payload as *const T as *const c_void;
-        try!(cvt(c::setsockopt(*sock.as_inner(), opt, val, payload,
-                               mem::size_of::<T>() as c::socklen_t)));
+        cvt(c::setsockopt(*sock.as_inner(), opt, val, payload,
+                               mem::size_of::<T>() as c::socklen_t))?;
         Ok(())
     }
 }
@@ -59,9 +59,9 @@ pub fn getsockopt<T: Copy>(sock: &Socket, opt: c_int,
     unsafe {
         let mut slot: T = mem::zeroed();
         let mut len = mem::size_of::<T>() as c::socklen_t;
-        try!(cvt(c::getsockopt(*sock.as_inner(), opt, val,
+        cvt(c::getsockopt(*sock.as_inner(), opt, val,
                                &mut slot as *mut _ as *mut _,
-                               &mut len)));
+                               &mut len))?;
         assert_eq!(len as usize, mem::size_of::<T>());
         Ok(slot)
     }
@@ -73,7 +73,7 @@ fn sockname<F>(f: F) -> io::Result<SocketAddr>
     unsafe {
         let mut storage: c::sockaddr_storage = mem::zeroed();
         let mut len = mem::size_of_val(&storage) as c::socklen_t;
-        try!(cvt(f(&mut storage as *mut _ as *mut _, &mut len)));
+        cvt(f(&mut storage as *mut _ as *mut _, &mut len))?;
         sockaddr_to_addr(&storage, len as usize)
     }
 }
@@ -143,11 +143,11 @@ impl Drop for LookupHost {
 pub fn lookup_host(host: &str) -> io::Result<LookupHost> {
     init();
 
-    let c_host = try!(CString::new(host));
+    let c_host = CString::new(host)?;
     let mut res = ptr::null_mut();
     unsafe {
-        try!(cvt_gai(c::getaddrinfo(c_host.as_ptr(), ptr::null(), ptr::null(),
-                                   &mut res)));
+        cvt_gai(c::getaddrinfo(c_host.as_ptr(), ptr::null(), ptr::null(),
+                                   &mut res))?;
         Ok(LookupHost { original: res, cur: res })
     }
 }
@@ -164,10 +164,10 @@ impl TcpStream {
     pub fn connect(addr: &SocketAddr) -> io::Result<TcpStream> {
         init();
 
-        let sock = try!(Socket::new(addr, c::SOCK_STREAM));
+        let sock = Socket::new(addr, c::SOCK_STREAM)?;
 
         let (addrp, len) = addr.into_inner();
-        try!(cvt_r(|| unsafe { c::connect(*sock.as_inner(), addrp, len) }));
+        cvt_r(|| unsafe { c::connect(*sock.as_inner(), addrp, len) })?;
         Ok(TcpStream { inner: sock })
     }
 
@@ -201,12 +201,12 @@ impl TcpStream {
 
     pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
         let len = cmp::min(buf.len(), <wrlen_t>::max_value() as usize) as wrlen_t;
-        let ret = try!(cvt(unsafe {
+        let ret = cvt(unsafe {
             c::send(*self.inner.as_inner(),
                     buf.as_ptr() as *const c_void,
                     len,
                     0)
-        }));
+        })?;
         Ok(ret as usize)
     }
 
@@ -243,7 +243,7 @@ impl TcpStream {
     }
 
     pub fn ttl(&self) -> io::Result<u32> {
-        let raw: c_int = try!(getsockopt(&self.inner, c::IPPROTO_IP, c::IP_TTL));
+        let raw: c_int = getsockopt(&self.inner, c::IPPROTO_IP, c::IP_TTL)?;
         Ok(raw as u32)
     }
 
@@ -252,7 +252,7 @@ impl TcpStream {
     }
 
     pub fn only_v6(&self) -> io::Result<bool> {
-        let raw: c_int = try!(getsockopt(&self.inner, c::IPPROTO_IPV6, c::IPV6_V6ONLY));
+        let raw: c_int = getsockopt(&self.inner, c::IPPROTO_IPV6, c::IPV6_V6ONLY)?;
         Ok(raw != 0)
     }
 
@@ -301,22 +301,22 @@ impl TcpListener {
     pub fn bind(addr: &SocketAddr) -> io::Result<TcpListener> {
         init();
 
-        let sock = try!(Socket::new(addr, c::SOCK_STREAM));
+        let sock = Socket::new(addr, c::SOCK_STREAM)?;
 
         // On platforms with Berkeley-derived sockets, this allows
         // to quickly rebind a socket, without needing to wait for
         // the OS to clean up the previous one.
         if !cfg!(windows) {
-            try!(setsockopt(&sock, c::SOL_SOCKET, c::SO_REUSEADDR,
-                            1 as c_int));
+            setsockopt(&sock, c::SOL_SOCKET, c::SO_REUSEADDR,
+                            1 as c_int)?;
         }
 
         // Bind our new socket
         let (addrp, len) = addr.into_inner();
-        try!(cvt(unsafe { c::bind(*sock.as_inner(), addrp, len) }));
+        cvt(unsafe { c::bind(*sock.as_inner(), addrp, len) })?;
 
         // Start listening
-        try!(cvt(unsafe { c::listen(*sock.as_inner(), 128) }));
+        cvt(unsafe { c::listen(*sock.as_inner(), 128) })?;
         Ok(TcpListener { inner: sock })
     }
 
@@ -333,9 +333,9 @@ impl TcpListener {
     pub fn accept(&self) -> io::Result<(TcpStream, SocketAddr)> {
         let mut storage: c::sockaddr_storage = unsafe { mem::zeroed() };
         let mut len = mem::size_of_val(&storage) as c::socklen_t;
-        let sock = try!(self.inner.accept(&mut storage as *mut _ as *mut _,
-                                          &mut len));
-        let addr = try!(sockaddr_to_addr(&storage, len as usize));
+        let sock = self.inner.accept(&mut storage as *mut _ as *mut _,
+                                          &mut len)?;
+        let addr = sockaddr_to_addr(&storage, len as usize)?;
         Ok((TcpStream { inner: sock, }, addr))
     }
 
@@ -348,7 +348,7 @@ impl TcpListener {
     }
 
     pub fn ttl(&self) -> io::Result<u32> {
-        let raw: c_int = try!(getsockopt(&self.inner, c::IPPROTO_IP, c::IP_TTL));
+        let raw: c_int = getsockopt(&self.inner, c::IPPROTO_IP, c::IP_TTL)?;
         Ok(raw as u32)
     }
 
@@ -357,7 +357,7 @@ impl TcpListener {
     }
 
     pub fn only_v6(&self) -> io::Result<bool> {
-        let raw: c_int = try!(getsockopt(&self.inner, c::IPPROTO_IPV6, c::IPV6_V6ONLY));
+        let raw: c_int = getsockopt(&self.inner, c::IPPROTO_IPV6, c::IPV6_V6ONLY)?;
         Ok(raw != 0)
     }
 
@@ -402,9 +402,9 @@ impl UdpSocket {
     pub fn bind(addr: &SocketAddr) -> io::Result<UdpSocket> {
         init();
 
-        let sock = try!(Socket::new(addr, c::SOCK_DGRAM));
+        let sock = Socket::new(addr, c::SOCK_DGRAM)?;
         let (addrp, len) = addr.into_inner();
-        try!(cvt(unsafe { c::bind(*sock.as_inner(), addrp, len) }));
+        cvt(unsafe { c::bind(*sock.as_inner(), addrp, len) })?;
         Ok(UdpSocket { inner: sock })
     }
 
@@ -423,23 +423,23 @@ impl UdpSocket {
         let mut addrlen = mem::size_of_val(&storage) as c::socklen_t;
         let len = cmp::min(buf.len(), <wrlen_t>::max_value() as usize) as wrlen_t;
 
-        let n = try!(cvt(unsafe {
+        let n = cvt(unsafe {
             c::recvfrom(*self.inner.as_inner(),
                         buf.as_mut_ptr() as *mut c_void,
                         len, 0,
                         &mut storage as *mut _ as *mut _, &mut addrlen)
-        }));
-        Ok((n as usize, try!(sockaddr_to_addr(&storage, addrlen as usize))))
+        })?;
+        Ok((n as usize, sockaddr_to_addr(&storage, addrlen as usize)?))
     }
 
     pub fn send_to(&self, buf: &[u8], dst: &SocketAddr) -> io::Result<usize> {
         let len = cmp::min(buf.len(), <wrlen_t>::max_value() as usize) as wrlen_t;
         let (dstp, dstlen) = dst.into_inner();
-        let ret = try!(cvt(unsafe {
+        let ret = cvt(unsafe {
             c::sendto(*self.inner.as_inner(),
                       buf.as_ptr() as *const c_void, len,
                       0, dstp, dstlen)
-        }));
+        })?;
         Ok(ret as usize)
     }
 
@@ -468,7 +468,7 @@ impl UdpSocket {
     }
 
     pub fn broadcast(&self) -> io::Result<bool> {
-        let raw: c_int = try!(getsockopt(&self.inner, c::SOL_SOCKET, c::SO_BROADCAST));
+        let raw: c_int = getsockopt(&self.inner, c::SOL_SOCKET, c::SO_BROADCAST)?;
         Ok(raw != 0)
     }
 
@@ -477,7 +477,7 @@ impl UdpSocket {
     }
 
     pub fn multicast_loop_v4(&self) -> io::Result<bool> {
-        let raw: c_int = try!(getsockopt(&self.inner, c::IPPROTO_IP, c::IP_MULTICAST_LOOP));
+        let raw: c_int = getsockopt(&self.inner, c::IPPROTO_IP, c::IP_MULTICAST_LOOP)?;
         Ok(raw != 0)
     }
 
@@ -486,7 +486,7 @@ impl UdpSocket {
     }
 
     pub fn multicast_ttl_v4(&self) -> io::Result<u32> {
-        let raw: c_int = try!(getsockopt(&self.inner, c::IPPROTO_IP, c::IP_MULTICAST_TTL));
+        let raw: c_int = getsockopt(&self.inner, c::IPPROTO_IP, c::IP_MULTICAST_TTL)?;
         Ok(raw as u32)
     }
 
@@ -495,7 +495,7 @@ impl UdpSocket {
     }
 
     pub fn multicast_loop_v6(&self) -> io::Result<bool> {
-        let raw: c_int = try!(getsockopt(&self.inner, c::IPPROTO_IPV6, c::IPV6_MULTICAST_LOOP));
+        let raw: c_int = getsockopt(&self.inner, c::IPPROTO_IPV6, c::IPV6_MULTICAST_LOOP)?;
         Ok(raw != 0)
     }
 
@@ -540,7 +540,7 @@ impl UdpSocket {
     }
 
     pub fn ttl(&self) -> io::Result<u32> {
-        let raw: c_int = try!(getsockopt(&self.inner, c::IPPROTO_IP, c::IP_TTL));
+        let raw: c_int = getsockopt(&self.inner, c::IPPROTO_IP, c::IP_TTL)?;
         Ok(raw as u32)
     }
 
@@ -549,7 +549,7 @@ impl UdpSocket {
     }
 
     pub fn only_v6(&self) -> io::Result<bool> {
-        let raw: c_int = try!(getsockopt(&self.inner, c::IPPROTO_IPV6, c::IPV6_V6ONLY));
+        let raw: c_int = getsockopt(&self.inner, c::IPPROTO_IPV6, c::IPV6_V6ONLY)?;
         Ok(raw != 0)
     }
 
@@ -567,12 +567,12 @@ impl UdpSocket {
 
     pub fn send(&self, buf: &[u8]) -> io::Result<usize> {
         let len = cmp::min(buf.len(), <wrlen_t>::max_value() as usize) as wrlen_t;
-        let ret = try!(cvt(unsafe {
+        let ret = cvt(unsafe {
             c::send(*self.inner.as_inner(),
                     buf.as_ptr() as *const c_void,
                     len,
                     0)
-        }));
+        })?;
         Ok(ret as usize)
     }
 

src/libstd/sys/common/remutex.rs

@@ -99,7 +99,7 @@ impl<T> ReentrantMutex<T> {
     /// acquired.
     pub fn try_lock(&self) -> TryLockResult<ReentrantMutexGuard<T>> {
         if unsafe { self.inner.try_lock() } {
-            Ok(try!(ReentrantMutexGuard::new(&self)))
+            Ok(ReentrantMutexGuard::new(&self)?)
         } else {
             Err(TryLockError::WouldBlock)
         }

src/libstd/sys/common/wtf8.rs

@@ -388,32 +388,32 @@ impl fmt::Debug for Wtf8 {
         fn write_str_escaped(f: &mut fmt::Formatter, s: &str) -> fmt::Result {
             use fmt::Write;
             for c in s.chars().flat_map(|c| c.escape_default()) {
-                try!(f.write_char(c))
+                f.write_char(c)?
             }
             Ok(())
         }
 
-        try!(formatter.write_str("\""));
+        formatter.write_str("\"")?;
         let mut pos = 0;
         loop {
             match self.next_surrogate(pos) {
                 None => break,
                 Some((surrogate_pos, surrogate)) => {
-                    try!(write_str_escaped(
+                    write_str_escaped(
                         formatter,
                         unsafe { str::from_utf8_unchecked(
                             &self.bytes[pos .. surrogate_pos]
                         )},
-                    ));
-                    try!(write!(formatter, "\\u{{{:X}}}", surrogate));
+                    )?;
+                    write!(formatter, "\\u{{{:X}}}", surrogate)?;
                     pos = surrogate_pos + 3;
                 }
             }
         }
-        try!(write_str_escaped(
+        write_str_escaped(
             formatter,
             unsafe { str::from_utf8_unchecked(&self.bytes[pos..]) },
-        ));
+        )?;
         formatter.write_str("\"")
     }
 }

src/libstd/sys/unix/backtrace/tracing/backtrace_fn.rs

@@ -40,7 +40,7 @@ pub fn write(w: &mut Write) -> io::Result<()> {
     static LOCK: StaticMutex = StaticMutex::new();
     let _g = LOCK.lock();
 
-    try!(writeln!(w, "stack backtrace:"));
+    writeln!(w, "stack backtrace:")?;
     // 100 lines should be enough
     const SIZE: usize = 100;
     let mut buf: [*mut libc::c_void; SIZE] = unsafe { mem::zeroed() };
@@ -48,7 +48,7 @@ pub fn write(w: &mut Write) -> io::Result<()> {
 
     // skipping the first one as it is write itself
     for i in 1..cnt {
-        try!(print(w, i as isize, buf[i], buf[i]))
+        print(w, i as isize, buf[i], buf[i])?
     }
     Ok(())
 }

src/libstd/sys/unix/backtrace/tracing/gcc_s.rs

@@ -33,7 +33,7 @@ pub fn write(w: &mut Write) -> io::Result<()> {
     static LOCK: StaticMutex = StaticMutex::new();
     let _g = LOCK.lock();
 
-    try!(writeln!(w, "stack backtrace:"));
+    writeln!(w, "stack backtrace:")?;
 
     let mut cx = Context { writer: w, last_error: None, idx: 0 };
     return match unsafe {

src/libstd/sys/unix/ext/net.rs

@@ -87,7 +87,7 @@ impl SocketAddr {
         unsafe {
             let mut addr: libc::sockaddr_un = mem::zeroed();
             let mut len = mem::size_of::<libc::sockaddr_un>() as libc::socklen_t;
-            try!(cvt(f(&mut addr as *mut _ as *mut _, &mut len)));
+            cvt(f(&mut addr as *mut _ as *mut _, &mut len))?;
             SocketAddr::from_parts(addr, len)
         }
     }
@@ -155,9 +155,9 @@ struct AsciiEscaped<'a>(&'a [u8]);
 
 impl<'a> fmt::Display for AsciiEscaped<'a> {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(fmt, "\""));
+        write!(fmt, "\"")?;
         for byte in self.0.iter().cloned().flat_map(ascii::escape_default) {
-            try!(write!(fmt, "{}", byte as char));
+            write!(fmt, "{}", byte as char)?;
         }
         write!(fmt, "\"")
     }
@@ -200,10 +200,10 @@ impl UnixStream {
     pub fn connect<P: AsRef<Path>>(path: P) -> io::Result<UnixStream> {
         fn inner(path: &Path) -> io::Result<UnixStream> {
             unsafe {
-                let inner = try!(Socket::new_raw(libc::AF_UNIX, libc::SOCK_STREAM));
-                let (addr, len) = try!(sockaddr_un(path));
+                let inner = Socket::new_raw(libc::AF_UNIX, libc::SOCK_STREAM)?;
+                let (addr, len) = sockaddr_un(path)?;
 
-                try!(cvt(libc::connect(*inner.as_inner(), &addr as *const _ as *const _, len)));
+                cvt(libc::connect(*inner.as_inner(), &addr as *const _ as *const _, len))?;
                 Ok(UnixStream(inner))
             }
         }
@@ -214,7 +214,7 @@ impl UnixStream {
     ///
     /// Returns two `UnixStream`s which are connected to each other.
     pub fn pair() -> io::Result<(UnixStream, UnixStream)> {
-        let (i1, i2) = try!(Socket::new_pair(libc::AF_UNIX, libc::SOCK_STREAM));
+        let (i1, i2) = Socket::new_pair(libc::AF_UNIX, libc::SOCK_STREAM)?;
         Ok((UnixStream(i1), UnixStream(i2)))
     }
 
@@ -395,11 +395,11 @@ impl UnixListener {
     pub fn bind<P: AsRef<Path>>(path: P) -> io::Result<UnixListener> {
         fn inner(path: &Path) -> io::Result<UnixListener> {
             unsafe {
-                let inner = try!(Socket::new_raw(libc::AF_UNIX, libc::SOCK_STREAM));
-                let (addr, len) = try!(sockaddr_un(path));
+                let inner = Socket::new_raw(libc::AF_UNIX, libc::SOCK_STREAM)?;
+                let (addr, len) = sockaddr_un(path)?;
 
-                try!(cvt(libc::bind(*inner.as_inner(), &addr as *const _ as *const _, len)));
-                try!(cvt(libc::listen(*inner.as_inner(), 128)));
+                cvt(libc::bind(*inner.as_inner(), &addr as *const _ as *const _, len))?;
+                cvt(libc::listen(*inner.as_inner(), 128))?;
 
                 Ok(UnixListener(inner))
             }
@@ -415,8 +415,8 @@ impl UnixListener {
     pub fn accept(&self) -> io::Result<(UnixStream, SocketAddr)> {
         let mut storage: libc::sockaddr_un = unsafe { mem::zeroed() };
         let mut len = mem::size_of_val(&storage) as libc::socklen_t;
-        let sock = try!(self.0.accept(&mut storage as *mut _ as *mut _, &mut len));
-        let addr = try!(SocketAddr::from_parts(storage, len));
+        let sock = self.0.accept(&mut storage as *mut _ as *mut _, &mut len)?;
+        let addr = SocketAddr::from_parts(storage, len)?;
         Ok((UnixStream(sock), addr))
     }
 
@@ -536,10 +536,10 @@ impl UnixDatagram {
     pub fn bind<P: AsRef<Path>>(path: P) -> io::Result<UnixDatagram> {
         fn inner(path: &Path) -> io::Result<UnixDatagram> {
             unsafe {
-                let socket = try!(UnixDatagram::unbound());
-                let (addr, len) = try!(sockaddr_un(path));
+                let socket = UnixDatagram::unbound()?;
+                let (addr, len) = sockaddr_un(path)?;
 
-                try!(cvt(libc::bind(*socket.0.as_inner(), &addr as *const _ as *const _, len)));
+                cvt(libc::bind(*socket.0.as_inner(), &addr as *const _ as *const _, len))?;
 
                 Ok(socket)
             }
@@ -549,7 +549,7 @@ impl UnixDatagram {
 
     /// Creates a Unix Datagram socket which is not bound to any address.
     pub fn unbound() -> io::Result<UnixDatagram> {
-        let inner = try!(Socket::new_raw(libc::AF_UNIX, libc::SOCK_DGRAM));
+        let inner = Socket::new_raw(libc::AF_UNIX, libc::SOCK_DGRAM)?;
         Ok(UnixDatagram(inner))
     }
 
@@ -557,7 +557,7 @@ impl UnixDatagram {
     ///
     /// Returns two `UnixDatagrams`s which are connected to each other.
     pub fn pair() -> io::Result<(UnixDatagram, UnixDatagram)> {
-        let (i1, i2) = try!(Socket::new_pair(libc::AF_UNIX, libc::SOCK_DGRAM));
+        let (i1, i2) = Socket::new_pair(libc::AF_UNIX, libc::SOCK_DGRAM)?;
         Ok((UnixDatagram(i1), UnixDatagram(i2)))
     }
 
@@ -568,9 +568,9 @@ impl UnixDatagram {
     pub fn connect<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
         fn inner(d: &UnixDatagram, path: &Path) -> io::Result<()> {
             unsafe {
-                let (addr, len) = try!(sockaddr_un(path));
+                let (addr, len) = sockaddr_un(path)?;
 
-                try!(cvt(libc::connect(*d.0.as_inner(), &addr as *const _ as *const _, len)));
+                cvt(libc::connect(*d.0.as_inner(), &addr as *const _ as *const _, len))?;
 
                 Ok(())
             }
@@ -605,7 +605,7 @@ impl UnixDatagram {
     /// whence the data came.
     pub fn recv_from(&self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
         let mut count = 0;
-        let addr = try!(SocketAddr::new(|addr, len| {
+        let addr = SocketAddr::new(|addr, len| {
             unsafe {
                 count = libc::recvfrom(*self.0.as_inner(),
                                        buf.as_mut_ptr() as *mut _,
@@ -621,7 +621,7 @@ impl UnixDatagram {
                     -1
                 }
             }
-        }));
+        })?;
 
         Ok((count as usize, addr))
     }
@@ -639,14 +639,14 @@ impl UnixDatagram {
     pub fn send_to<P: AsRef<Path>>(&self, buf: &[u8], path: P) -> io::Result<usize> {
         fn inner(d: &UnixDatagram, buf: &[u8], path: &Path) -> io::Result<usize> {
             unsafe {
-                let (addr, len) = try!(sockaddr_un(path));
+                let (addr, len) = sockaddr_un(path)?;
 
-                let count = try!(cvt(libc::sendto(*d.0.as_inner(),
+                let count = cvt(libc::sendto(*d.0.as_inner(),
                                                   buf.as_ptr() as *const _,
                                                   buf.len(),
                                                   0,
                                                   &addr as *const _ as *const _,
-                                                  len)));
+                                                  len))?;
                 Ok(count as usize)
             }
         }

src/libstd/sys/unix/fd.rs

@@ -39,11 +39,11 @@ impl FileDesc {
     }
 
     pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
-        let ret = try!(cvt(unsafe {
+        let ret = cvt(unsafe {
             libc::read(self.fd,
                        buf.as_mut_ptr() as *mut c_void,
                        buf.len() as size_t)
-        }));
+        })?;
         Ok(ret as usize)
     }
 
@@ -53,11 +53,11 @@ impl FileDesc {
     }
 
     pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
-        let ret = try!(cvt(unsafe {
+        let ret = cvt(unsafe {
             libc::write(self.fd,
                         buf.as_ptr() as *const c_void,
                         buf.len() as size_t)
-        }));
+        })?;
         Ok(ret as usize)
     }
 

src/libstd/sys/unix/fs.rs

@@ -418,18 +418,18 @@ impl OpenOptions {
 
 impl File {
     pub fn open(path: &Path, opts: &OpenOptions) -> io::Result<File> {
-        let path = try!(cstr(path));
+        let path = cstr(path)?;
         File::open_c(&path, opts)
     }
 
     pub fn open_c(path: &CStr, opts: &OpenOptions) -> io::Result<File> {
         let flags = libc::O_CLOEXEC |
-                    try!(opts.get_access_mode()) |
-                    try!(opts.get_creation_mode()) |
+                    opts.get_access_mode()? |
+                    opts.get_creation_mode()? |
                     (opts.custom_flags as c_int & !libc::O_ACCMODE);
-        let fd = try!(cvt_r(|| unsafe {
+        let fd = cvt_r(|| unsafe {
             open64(path.as_ptr(), flags, opts.mode as c_int)
-        }));
+        })?;
         let fd = FileDesc::new(fd);
 
         // Currently the standard library supports Linux 2.6.18 which did not
@@ -448,19 +448,19 @@ impl File {
 
     pub fn file_attr(&self) -> io::Result<FileAttr> {
         let mut stat: stat64 = unsafe { mem::zeroed() };
-        try!(cvt(unsafe {
+        cvt(unsafe {
             fstat64(self.0.raw(), &mut stat)
-        }));
+        })?;
         Ok(FileAttr { stat: stat })
     }
 
     pub fn fsync(&self) -> io::Result<()> {
-        try!(cvt_r(|| unsafe { libc::fsync(self.0.raw()) }));
+        cvt_r(|| unsafe { libc::fsync(self.0.raw()) })?;
         Ok(())
     }
 
     pub fn datasync(&self) -> io::Result<()> {
-        try!(cvt_r(|| unsafe { os_datasync(self.0.raw()) }));
+        cvt_r(|| unsafe { os_datasync(self.0.raw()) })?;
         return Ok(());
 
         #[cfg(any(target_os = "macos", target_os = "ios"))]
@@ -476,9 +476,9 @@ impl File {
     }
 
     pub fn truncate(&self, size: u64) -> io::Result<()> {
-        try!(cvt_r(|| unsafe {
+        cvt_r(|| unsafe {
             ftruncate64(self.0.raw(), size as off64_t)
-        }));
+        })?;
         Ok(())
     }
 
@@ -502,7 +502,7 @@ impl File {
             SeekFrom::End(off) => (libc::SEEK_END, off as off64_t),
             SeekFrom::Current(off) => (libc::SEEK_CUR, off as off64_t),
         };
-        let n = try!(cvt(unsafe { lseek64(self.0.raw(), pos, whence) }));
+        let n = cvt(unsafe { lseek64(self.0.raw(), pos, whence) })?;
         Ok(n as u64)
     }
 
@@ -521,8 +521,8 @@ impl DirBuilder {
     }
 
     pub fn mkdir(&self, p: &Path) -> io::Result<()> {
-        let p = try!(cstr(p));
-        try!(cvt(unsafe { libc::mkdir(p.as_ptr(), self.mode) }));
+        let p = cstr(p)?;
+        cvt(unsafe { libc::mkdir(p.as_ptr(), self.mode) })?;
         Ok(())
     }
 
@@ -532,7 +532,7 @@ impl DirBuilder {
 }
 
 fn cstr(path: &Path) -> io::Result<CString> {
-    Ok(try!(CString::new(path.as_os_str().as_bytes())))
+    Ok(CString::new(path.as_os_str().as_bytes())?)
 }
 
 impl FromInner<c_int> for File {
@@ -610,7 +610,7 @@ impl fmt::Debug for File {
 
 pub fn readdir(p: &Path) -> io::Result<ReadDir> {
     let root = Arc::new(p.to_path_buf());
-    let p = try!(cstr(p));
+    let p = cstr(p)?;
     unsafe {
         let ptr = libc::opendir(p.as_ptr());
         if ptr.is_null() {
@@ -622,32 +622,32 @@ pub fn readdir(p: &Path) -> io::Result<ReadDir> {
 }
 
 pub fn unlink(p: &Path) -> io::Result<()> {
-    let p = try!(cstr(p));
-    try!(cvt(unsafe { libc::unlink(p.as_ptr()) }));
+    let p = cstr(p)?;
+    cvt(unsafe { libc::unlink(p.as_ptr()) })?;
     Ok(())
 }
 
 pub fn rename(old: &Path, new: &Path) -> io::Result<()> {
-    let old = try!(cstr(old));
-    let new = try!(cstr(new));
-    try!(cvt(unsafe { libc::rename(old.as_ptr(), new.as_ptr()) }));
+    let old = cstr(old)?;
+    let new = cstr(new)?;
+    cvt(unsafe { libc::rename(old.as_ptr(), new.as_ptr()) })?;
     Ok(())
 }
 
 pub fn set_perm(p: &Path, perm: FilePermissions) -> io::Result<()> {
-    let p = try!(cstr(p));
-    try!(cvt_r(|| unsafe { libc::chmod(p.as_ptr(), perm.mode) }));
+    let p = cstr(p)?;
+    cvt_r(|| unsafe { libc::chmod(p.as_ptr(), perm.mode) })?;
     Ok(())
 }
 
 pub fn rmdir(p: &Path) -> io::Result<()> {
-    let p = try!(cstr(p));
-    try!(cvt(unsafe { libc::rmdir(p.as_ptr()) }));
+    let p = cstr(p)?;
+    cvt(unsafe { libc::rmdir(p.as_ptr()) })?;
     Ok(())
 }
 
 pub fn remove_dir_all(path: &Path) -> io::Result<()> {
-    let filetype = try!(lstat(path)).file_type();
+    let filetype = lstat(path)?.file_type();
     if filetype.is_symlink() {
         unlink(path)
     } else {
@@ -656,27 +656,27 @@ pub fn remove_dir_all(path: &Path) -> io::Result<()> {
 }
 
 fn remove_dir_all_recursive(path: &Path) -> io::Result<()> {
-    for child in try!(readdir(path)) {
-        let child = try!(child);
-        if try!(child.file_type()).is_dir() {
-            try!(remove_dir_all_recursive(&child.path()));
+    for child in readdir(path)? {
+        let child = child?;
+        if child.file_type()?.is_dir() {
+            remove_dir_all_recursive(&child.path())?;
         } else {
-            try!(unlink(&child.path()));
+            unlink(&child.path())?;
         }
     }
     rmdir(path)
 }
 
 pub fn readlink(p: &Path) -> io::Result<PathBuf> {
-    let c_path = try!(cstr(p));
+    let c_path = cstr(p)?;
     let p = c_path.as_ptr();
 
     let mut buf = Vec::with_capacity(256);
 
     loop {
-        let buf_read = try!(cvt(unsafe {
+        let buf_read = cvt(unsafe {
             libc::readlink(p, buf.as_mut_ptr() as *mut _, buf.capacity() as libc::size_t)
-        })) as usize;
+        })? as usize;
 
         unsafe { buf.set_len(buf_read); }
 
@@ -694,39 +694,39 @@ pub fn readlink(p: &Path) -> io::Result<PathBuf> {
 }
 
 pub fn symlink(src: &Path, dst: &Path) -> io::Result<()> {
-    let src = try!(cstr(src));
-    let dst = try!(cstr(dst));
-    try!(cvt(unsafe { libc::symlink(src.as_ptr(), dst.as_ptr()) }));
+    let src = cstr(src)?;
+    let dst = cstr(dst)?;
+    cvt(unsafe { libc::symlink(src.as_ptr(), dst.as_ptr()) })?;
     Ok(())
 }
 
 pub fn link(src: &Path, dst: &Path) -> io::Result<()> {
-    let src = try!(cstr(src));
-    let dst = try!(cstr(dst));
-    try!(cvt(unsafe { libc::link(src.as_ptr(), dst.as_ptr()) }));
+    let src = cstr(src)?;
+    let dst = cstr(dst)?;
+    cvt(unsafe { libc::link(src.as_ptr(), dst.as_ptr()) })?;
     Ok(())
 }
 
 pub fn stat(p: &Path) -> io::Result<FileAttr> {
-    let p = try!(cstr(p));
+    let p = cstr(p)?;
     let mut stat: stat64 = unsafe { mem::zeroed() };
-    try!(cvt(unsafe {
+    cvt(unsafe {
         stat64(p.as_ptr(), &mut stat as *mut _ as *mut _)
-    }));
+    })?;
     Ok(FileAttr { stat: stat })
 }
 
 pub fn lstat(p: &Path) -> io::Result<FileAttr> {
-    let p = try!(cstr(p));
+    let p = cstr(p)?;
     let mut stat: stat64 = unsafe { mem::zeroed() };
-    try!(cvt(unsafe {
+    cvt(unsafe {
         lstat64(p.as_ptr(), &mut stat as *mut _ as *mut _)
-    }));
+    })?;
     Ok(FileAttr { stat: stat })
 }
 
 pub fn canonicalize(p: &Path) -> io::Result<PathBuf> {
-    let path = try!(CString::new(p.as_os_str().as_bytes()));
+    let path = CString::new(p.as_os_str().as_bytes())?;
     let buf;
     unsafe {
         let r = libc::realpath(path.as_ptr(), ptr::null_mut());
@@ -746,11 +746,11 @@ pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
                               "the source path is not an existing regular file"))
     }
 
-    let mut reader = try!(File::open(from));
-    let mut writer = try!(File::create(to));
-    let perm = try!(reader.metadata()).permissions();
+    let mut reader = File::open(from)?;
+    let mut writer = File::create(to)?;
+    let perm = reader.metadata()?.permissions();
 
-    let ret = try!(io::copy(&mut reader, &mut writer));
-    try!(set_permissions(to, perm));
+    let ret = io::copy(&mut reader, &mut writer)?;
+    set_permissions(to, perm)?;
     Ok(ret)
 }

src/libstd/sys/unix/net.rs

@@ -75,7 +75,7 @@ impl Socket {
                 }
             }
 
-            let fd = try!(cvt(libc::socket(fam, ty, 0)));
+            let fd = cvt(libc::socket(fam, ty, 0))?;
             let fd = FileDesc::new(fd);
             fd.set_cloexec();
             Ok(Socket(fd))
@@ -97,7 +97,7 @@ impl Socket {
                 }
             }
 
-            try!(cvt(libc::socketpair(fam, ty, 0, fds.as_mut_ptr())));
+            cvt(libc::socketpair(fam, ty, 0, fds.as_mut_ptr()))?;
             let a = FileDesc::new(fds[0]);
             a.set_cloexec();
             let b = FileDesc::new(fds[1]);
@@ -128,9 +128,9 @@ impl Socket {
             }
         }
 
-        let fd = try!(cvt_r(|| unsafe {
+        let fd = cvt_r(|| unsafe {
             libc::accept(self.0.raw(), storage, len)
-        }));
+        })?;
         let fd = FileDesc::new(fd);
         fd.set_cloexec();
         Ok(Socket(fd))
@@ -185,7 +185,7 @@ impl Socket {
     }
 
     pub fn timeout(&self, kind: libc::c_int) -> io::Result<Option<Duration>> {
-        let raw: libc::timeval = try!(getsockopt(self, libc::SOL_SOCKET, kind));
+        let raw: libc::timeval = getsockopt(self, libc::SOL_SOCKET, kind)?;
         if raw.tv_sec == 0 && raw.tv_usec == 0 {
             Ok(None)
         } else {
@@ -201,7 +201,7 @@ impl Socket {
             Shutdown::Read => libc::SHUT_RD,
             Shutdown::Both => libc::SHUT_RDWR,
         };
-        try!(cvt(unsafe { libc::shutdown(self.0.raw(), how) }));
+        cvt(unsafe { libc::shutdown(self.0.raw(), how) })?;
         Ok(())
     }
 
@@ -210,7 +210,7 @@ impl Socket {
     }
 
     pub fn nodelay(&self) -> io::Result<bool> {
-        let raw: c_int = try!(getsockopt(self, libc::IPPROTO_TCP, libc::TCP_NODELAY));
+        let raw: c_int = getsockopt(self, libc::IPPROTO_TCP, libc::TCP_NODELAY)?;
         Ok(raw != 0)
     }
 
@@ -220,7 +220,7 @@ impl Socket {
     }
 
     pub fn take_error(&self) -> io::Result<Option<io::Error>> {
-        let raw: c_int = try!(getsockopt(self, libc::SOL_SOCKET, libc::SO_ERROR));
+        let raw: c_int = getsockopt(self, libc::SOL_SOCKET, libc::SO_ERROR)?;
         if raw == 0 {
             Ok(None)
         } else {

src/libstd/sys/unix/os.rs

@@ -110,7 +110,7 @@ pub fn getcwd() -> io::Result<PathBuf> {
 
 pub fn chdir(p: &path::Path) -> io::Result<()> {
     let p: &OsStr = p.as_ref();
-    let p = try!(CString::new(p.as_bytes()));
+    let p = CString::new(p.as_bytes())?;
     unsafe {
         match libc::chdir(p.as_ptr()) == (0 as c_int) {
             true => Ok(()),
@@ -180,16 +180,16 @@ pub fn current_exe() -> io::Result<PathBuf> {
                        libc::KERN_PROC_PATHNAME as c_int,
                        -1 as c_int];
         let mut sz: libc::size_t = 0;
-        try!(cvt(libc::sysctl(mib.as_mut_ptr(), mib.len() as ::libc::c_uint,
+        cvt(libc::sysctl(mib.as_mut_ptr(), mib.len() as ::libc::c_uint,
                               ptr::null_mut(), &mut sz, ptr::null_mut(),
-                              0 as libc::size_t)));
+                              0 as libc::size_t))?;
         if sz == 0 {
             return Err(io::Error::last_os_error())
         }
         let mut v: Vec<u8> = Vec::with_capacity(sz as usize);
-        try!(cvt(libc::sysctl(mib.as_mut_ptr(), mib.len() as ::libc::c_uint,
+        cvt(libc::sysctl(mib.as_mut_ptr(), mib.len() as ::libc::c_uint,
                               v.as_mut_ptr() as *mut libc::c_void, &mut sz,
-                              ptr::null_mut(), 0 as libc::size_t)));
+                              ptr::null_mut(), 0 as libc::size_t))?;
         if sz == 0 {
             return Err(io::Error::last_os_error());
         }
@@ -217,11 +217,11 @@ pub fn current_exe() -> io::Result<PathBuf> {
                        libc::KERN_PROC_ARGV];
         let mib = mib.as_mut_ptr();
         let mut argv_len = 0;
-        try!(cvt(libc::sysctl(mib, 4, 0 as *mut _, &mut argv_len,
-                              0 as *mut _, 0)));
+        cvt(libc::sysctl(mib, 4, 0 as *mut _, &mut argv_len,
+                              0 as *mut _, 0))?;
         let mut argv = Vec::<*const libc::c_char>::with_capacity(argv_len as usize);
-        try!(cvt(libc::sysctl(mib, 4, argv.as_mut_ptr() as *mut _,
-                              &mut argv_len, 0 as *mut _, 0)));
+        cvt(libc::sysctl(mib, 4, argv.as_mut_ptr() as *mut _,
+                              &mut argv_len, 0 as *mut _, 0))?;
         argv.set_len(argv_len as usize);
         if argv[0].is_null() {
             return Err(io::Error::new(io::ErrorKind::Other,
@@ -460,7 +460,7 @@ pub fn env() -> Env {
 pub fn getenv(k: &OsStr) -> io::Result<Option<OsString>> {
     // environment variables with a nul byte can't be set, so their value is
     // always None as well
-    let k = try!(CString::new(k.as_bytes()));
+    let k = CString::new(k.as_bytes())?;
     let _g = ENV_LOCK.lock();
     Ok(unsafe {
         let s = libc::getenv(k.as_ptr()) as *const _;
@@ -473,8 +473,8 @@ pub fn getenv(k: &OsStr) -> io::Result<Option<OsString>> {
 }
 
 pub fn setenv(k: &OsStr, v: &OsStr) -> io::Result<()> {
-    let k = try!(CString::new(k.as_bytes()));
-    let v = try!(CString::new(v.as_bytes()));
+    let k = CString::new(k.as_bytes())?;
+    let v = CString::new(v.as_bytes())?;
     let _g = ENV_LOCK.lock();
     cvt(unsafe {
         libc::setenv(k.as_ptr(), v.as_ptr(), 1)
@@ -482,7 +482,7 @@ pub fn setenv(k: &OsStr, v: &OsStr) -> io::Result<()> {
 }
 
 pub fn unsetenv(n: &OsStr) -> io::Result<()> {
-    let nbuf = try!(CString::new(n.as_bytes()));
+    let nbuf = CString::new(n.as_bytes())?;
     let _g = ENV_LOCK.lock();
     cvt(unsafe {
         libc::unsetenv(nbuf.as_ptr())

src/libstd/sys/unix/pipe.rs

@@ -87,13 +87,13 @@ pub fn read2(p1: AnonPipe,
     let max = cmp::max(p1.raw(), p2.raw());
     loop {
         // wait for either pipe to become readable using `select`
-        try!(cvt_r(|| unsafe {
+        cvt_r(|| unsafe {
             let mut read: libc::fd_set = mem::zeroed();
             libc::FD_SET(p1.raw(), &mut read);
             libc::FD_SET(p2.raw(), &mut read);
             libc::select(max + 1, &mut read, 0 as *mut _, 0 as *mut _,
                          0 as *mut _)
-        }));
+        })?;
 
         // Read as much as we can from each pipe, ignoring EWOULDBLOCK or
         // EAGAIN. If we hit EOF, then this will happen because the underlying
@@ -113,11 +113,11 @@ pub fn read2(p1: AnonPipe,
                 }
             }
         };
-        if try!(read(&p1, v1)) {
+        if read(&p1, v1)? {
             p2.set_nonblocking(false);
             return p2.read_to_end(v2).map(|_| ());
         }
-        if try!(read(&p2, v2)) {
+        if read(&p2, v2)? {
             p1.set_nonblocking(false);
             return p1.read_to_end(v1).map(|_| ());
         }

src/libstd/sys/unix/process.rs

@@ -225,11 +225,11 @@ impl Command {
                                       "nul byte found in provided data"));
         }
 
-        let (ours, theirs) = try!(self.setup_io(default, needs_stdin));
-        let (input, output) = try!(sys::pipe::anon_pipe());
+        let (ours, theirs) = self.setup_io(default, needs_stdin)?;
+        let (input, output) = sys::pipe::anon_pipe()?;
 
         let pid = unsafe {
-            match try!(cvt(libc::fork())) {
+            match cvt(libc::fork())? {
                 0 => {
                     drop(input);
                     let err = self.do_exec(theirs);
@@ -343,17 +343,17 @@ impl Command {
         }
 
         if let Some(fd) = stdio.stdin.fd() {
-            try!(cvt_r(|| libc::dup2(fd, libc::STDIN_FILENO)));
+            cvt_r(|| libc::dup2(fd, libc::STDIN_FILENO))?;
         }
         if let Some(fd) = stdio.stdout.fd() {
-            try!(cvt_r(|| libc::dup2(fd, libc::STDOUT_FILENO)));
+            cvt_r(|| libc::dup2(fd, libc::STDOUT_FILENO))?;
         }
         if let Some(fd) = stdio.stderr.fd() {
-            try!(cvt_r(|| libc::dup2(fd, libc::STDERR_FILENO)));
+            cvt_r(|| libc::dup2(fd, libc::STDERR_FILENO))?;
         }
 
         if let Some(u) = self.gid {
-            try!(cvt(libc::setgid(u as gid_t)));
+            cvt(libc::setgid(u as gid_t))?;
         }
         if let Some(u) = self.uid {
             // When dropping privileges from root, the `setgroups` call
@@ -365,7 +365,7 @@ impl Command {
             // privilege dropping function.
             let _ = libc::setgroups(0, ptr::null());
 
-            try!(cvt(libc::setuid(u as uid_t)));
+            cvt(libc::setuid(u as uid_t))?;
         }
         if self.session_leader {
             // Don't check the error of setsid because it fails if we're the
@@ -374,7 +374,7 @@ impl Command {
             let _ = libc::setsid();
         }
         if let Some(ref cwd) = self.cwd {
-            try!(cvt(libc::chdir(cwd.as_ptr())));
+            cvt(libc::chdir(cwd.as_ptr()))?;
         }
         if let Some(ref envp) = self.envp {
             *sys::os::environ() = envp.as_ptr();
@@ -390,9 +390,9 @@ impl Command {
             // need to clean things up now to avoid confusing the program
             // we're about to run.
             let mut set: libc::sigset_t = mem::uninitialized();
-            try!(cvt(libc::sigemptyset(&mut set)));
-            try!(cvt(libc::pthread_sigmask(libc::SIG_SETMASK, &set,
-                                           ptr::null_mut())));
+            cvt(libc::sigemptyset(&mut set))?;
+            cvt(libc::pthread_sigmask(libc::SIG_SETMASK, &set,
+                                           ptr::null_mut()))?;
             let ret = libc::signal(libc::SIGPIPE, libc::SIG_DFL);
             if ret == libc::SIG_ERR {
                 return io::Error::last_os_error()
@@ -400,7 +400,7 @@ impl Command {
         }
 
         for callback in self.closures.iter_mut() {
-            try!(callback());
+            callback()?;
         }
 
         libc::execvp(self.argv[0], self.argv.as_ptr());
@@ -415,9 +415,9 @@ impl Command {
         let stdin = self.stdin.as_ref().unwrap_or(default_stdin);
         let stdout = self.stdout.as_ref().unwrap_or(&default);
         let stderr = self.stderr.as_ref().unwrap_or(&default);
-        let (their_stdin, our_stdin) = try!(stdin.to_child_stdio(true));
-        let (their_stdout, our_stdout) = try!(stdout.to_child_stdio(false));
-        let (their_stderr, our_stderr) = try!(stderr.to_child_stdio(false));
+        let (their_stdin, our_stdin) = stdin.to_child_stdio(true)?;
+        let (their_stdout, our_stdout) = stdout.to_child_stdio(false)?;
+        let (their_stderr, our_stderr) = stderr.to_child_stdio(false)?;
         let ours = StdioPipes {
             stdin: our_stdin,
             stdout: our_stdout,
@@ -454,14 +454,14 @@ impl Stdio {
             // overwritten prematurely.
             Stdio::Fd(ref fd) => {
                 if fd.raw() >= 0 && fd.raw() <= libc::STDERR_FILENO {
-                    Ok((ChildStdio::Owned(try!(fd.duplicate())), None))
+                    Ok((ChildStdio::Owned(fd.duplicate()?), None))
                 } else {
                     Ok((ChildStdio::Explicit(fd.raw()), None))
                 }
             }
 
             Stdio::MakePipe => {
-                let (reader, writer) = try!(pipe::anon_pipe());
+                let (reader, writer) = pipe::anon_pipe()?;
                 let (ours, theirs) = if readable {
                     (writer, reader)
                 } else {
@@ -477,7 +477,7 @@ impl Stdio {
                 let path = unsafe {
                     CStr::from_ptr("/dev/null\0".as_ptr() as *const _)
                 };
-                let fd = try!(File::open_c(&path, &opts));
+                let fd = File::open_c(&path, &opts)?;
                 Ok((ChildStdio::Owned(fd.into_fd()), None))
             }
         }
@@ -508,9 +508,9 @@ fn pair_to_key(key: &OsStr, value: &OsStr, saw_nul: &mut bool) -> CString {
 
 impl fmt::Debug for Command {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(f, "{:?}", self.program));
+        write!(f, "{:?}", self.program)?;
         for arg in &self.args {
-            try!(write!(f, " {:?}", arg));
+            write!(f, " {:?}", arg)?;
         }
         Ok(())
     }
@@ -589,7 +589,7 @@ impl Process {
             return Ok(status)
         }
         let mut status = 0 as c_int;
-        try!(cvt_r(|| unsafe { libc::waitpid(self.pid, &mut status, 0) }));
+        cvt_r(|| unsafe { libc::waitpid(self.pid, &mut status, 0) })?;
         self.status = Some(ExitStatus(status));
         Ok(ExitStatus(status))
     }

src/libstd/sys/unix/rand.rs

@@ -138,7 +138,7 @@ mod imp {
                 return Ok(OsRng { inner: OsGetrandomRng });
             }
 
-            let reader = try!(File::open("/dev/urandom"));
+            let reader = File::open("/dev/urandom")?;
             let reader_rng = ReaderRng::new(reader);
 
             Ok(OsRng { inner: OsReaderRng(reader_rng) })