syntax: Replace String::from_str with the stable String::from

src/libsyntax/ast_util.rs

@@ -238,7 +238,7 @@ pub fn name_to_dummy_lifetime(name: Name) -> Lifetime {
 pub fn impl_pretty_name(trait_ref: &Option<TraitRef>, ty: Option<&Ty>) -> Ident {
     let mut pretty = match ty {
         Some(t) => pprust::ty_to_string(t),
-        None => String::from_str("..")
+        None => String::from("..")
     };
 
     match *trait_ref {

src/libsyntax/codemap.rs

@@ -557,9 +557,9 @@ impl CodeMap {
         // FIXME #12884: no efficient/safe way to remove from the start of a string
         // and reuse the allocation.
         let mut src = if src.starts_with("\u{feff}") {
-            String::from_str(&src[3..])
+            String::from(&src[3..])
         } else {
-            String::from_str(&src[..])
+            String::from(&src[..])
         };
 
         // Append '\n' in case it's not already there.

src/libsyntax/diagnostic.rs

@@ -644,7 +644,7 @@ fn highlight_lines(err: &mut EmitterWriter,
             }
 
             try!(write!(&mut err.dst, "{}", s));
-            let mut s = String::from_str("^");
+            let mut s = String::from("^");
             let count = match lastc {
                 // Most terminals have a tab stop every eight columns by default
                 '\t' => 8 - col%8,

src/libsyntax/parse/lexer/comments.rs

@@ -246,7 +246,7 @@ fn read_block_comment(rdr: &mut StringReader,
     rdr.bump();
     rdr.bump();
 
-    let mut curr_line = String::from_str("/*");
+    let mut curr_line = String::from("/*");
 
     // doc-comments are not really comments, they are attributes
     if (rdr.curr_is('*') && !rdr.nextch_is('*')) || rdr.curr_is('!') {

src/libsyntax/parse/parser.rs

@@ -4834,7 +4834,7 @@ impl<'a> Parser<'a> {
         let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut();
         match included_mod_stack.iter().position(|p| *p == path) {
             Some(i) => {
-                let mut err = String::from_str("circular modules: ");
+                let mut err = String::from("circular modules: ");
                 let len = included_mod_stack.len();
                 for p in &included_mod_stack[i.. len] {
                     err.push_str(&p.to_string_lossy());

src/libsyntax/print/pp.rs

@@ -131,7 +131,7 @@ pub fn buf_str(toks: &[Token],
     assert_eq!(n, szs.len());
     let mut i = left;
     let mut l = lim;
-    let mut s = string::String::from_str("[");
+    let mut s = string::String::from("[");
     while i != right && l != 0 {
         l -= 1;
         if i != left {

src/libsyntax/print/pprust.rs

@@ -2794,13 +2794,13 @@ impl<'a> State<'a> {
         match lit.node {
             ast::LitStr(ref st, style) => self.print_string(&st, style),
             ast::LitByte(byte) => {
-                let mut res = String::from_str("b'");
+                let mut res = String::from("b'");
                 res.extend(ascii::escape_default(byte).map(|c| c as char));
                 res.push('\'');
                 word(&mut self.s, &res[..])
             }
             ast::LitChar(ch) => {
-                let mut res = String::from_str("'");
+                let mut res = String::from("'");
                 res.extend(ch.escape_default());
                 res.push('\'');
                 word(&mut self.s, &res[..])