Some work

compiler/rustc_errors/src/json.rs

@@ -145,10 +145,11 @@ impl Emitter for JsonEmitter {
                 }
             })
             .collect();
+        let report = FutureIncompatReport { future_incompat_report: data };
         let result = if self.pretty {
-            writeln!(&mut self.dst, "{}", as_pretty_json(&data))
+            writeln!(&mut self.dst, "{}", as_pretty_json(&report))
         } else {
-            writeln!(&mut self.dst, "{}", as_json(&data))
+            writeln!(&mut self.dst, "{}", as_json(&report))
         }
         .and_then(|_| self.dst.flush());
         if let Err(e) = result {
@@ -254,6 +255,11 @@ struct FutureBreakageItem {
     diagnostic: Diagnostic,
 }
 
+#[derive(Encodable)]
+struct FutureIncompatReport {
+    future_incompat_report: Vec<FutureBreakageItem>,
+}
+
 impl Diagnostic {
     fn from_errors_diagnostic(diag: &crate::Diagnostic, je: &JsonEmitter) -> Diagnostic {
         let sugg = diag.suggestions.iter().map(|sugg| Diagnostic {

compiler/rustc_session/src/options.rs

@@ -893,8 +893,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         all `statement`s (including terminators), only `terminator` spans, or \
         computed `block` spans (one span encompassing a block's terminator and \
         all statements)."),
-    emit_future_compat_report: bool = (false, parse_bool, [UNTRACKED],
+    emit_future_incompat_report: bool = (false, parse_bool, [UNTRACKED],
-        "emits a future-compatibility report for lints (RFC 2834)"),
+        "emits a future-incompatibility report for lints (RFC 2834)"),
     emit_stack_sizes: bool = (false, parse_bool, [UNTRACKED],
         "emit a section containing stack size metadata (default: no)"),
     fewer_names: bool = (false, parse_bool, [TRACKED],

compiler/rustc_session/src/session.rs

@@ -308,7 +308,7 @@ impl Session {
     }
 
     fn emit_future_breakage(&self) {
-        if !self.opts.debugging_opts.emit_future_compat_report {
+        if !self.opts.debugging_opts.emit_future_incompat_report {
             return;
         }
 

src/test/ui/iterators/into-iter-on-arrays-lint.fixed

@@ -1,5 +1,6 @@
 // run-pass
 // run-rustfix
+// compiler-flags: -Z emit-future-compat-report
 
 fn main() {
     let small = [1, 2];

src/test/ui/iterators/into-iter-on-arrays-lint.rs

@@ -1,5 +1,6 @@
 // run-pass
 // run-rustfix
+// compile-flags: -Z emit-future-incompat-report
 
 fn main() {
     let small = [1, 2];

src/test/ui/iterators/into-iter-on-arrays-lint.stderr

@@ -1,5 +1,5 @@
 warning: this method call currently resolves to `<&[T; N] as IntoIterator>::into_iter` (due to autoref coercions), but that might change in the future when `IntoIterator` impls for arrays are added.
-  --> $DIR/into-iter-on-arrays-lint.rs:9:11
+  --> $DIR/into-iter-on-arrays-lint.rs:10:11
    |
 LL |     small.into_iter();
    |           ^^^^^^^^^ help: use `.iter()` instead of `.into_iter()` to avoid ambiguity: `iter`
@@ -9,7 +9,7 @@ LL |     small.into_iter();
    = note: for more information, see issue #66145 <https://github.com/rust-lang/rust/issues/66145>
 
 warning: this method call currently resolves to `<&[T; N] as IntoIterator>::into_iter` (due to autoref coercions), but that might change in the future when `IntoIterator` impls for arrays are added.
-  --> $DIR/into-iter-on-arrays-lint.rs:12:12
+  --> $DIR/into-iter-on-arrays-lint.rs:13:12
    |
 LL |     [1, 2].into_iter();
    |            ^^^^^^^^^ help: use `.iter()` instead of `.into_iter()` to avoid ambiguity: `iter`
@@ -18,7 +18,7 @@ LL |     [1, 2].into_iter();
    = note: for more information, see issue #66145 <https://github.com/rust-lang/rust/issues/66145>
 
 warning: this method call currently resolves to `<&[T; N] as IntoIterator>::into_iter` (due to autoref coercions), but that might change in the future when `IntoIterator` impls for arrays are added.
-  --> $DIR/into-iter-on-arrays-lint.rs:15:9
+  --> $DIR/into-iter-on-arrays-lint.rs:16:9
    |
 LL |     big.into_iter();
    |         ^^^^^^^^^ help: use `.iter()` instead of `.into_iter()` to avoid ambiguity: `iter`
@@ -27,7 +27,7 @@ LL |     big.into_iter();
    = note: for more information, see issue #66145 <https://github.com/rust-lang/rust/issues/66145>
 
 warning: this method call currently resolves to `<&[T; N] as IntoIterator>::into_iter` (due to autoref coercions), but that might change in the future when `IntoIterator` impls for arrays are added.
-  --> $DIR/into-iter-on-arrays-lint.rs:18:15
+  --> $DIR/into-iter-on-arrays-lint.rs:19:15
    |
 LL |     [0u8; 33].into_iter();
    |               ^^^^^^^^^ help: use `.iter()` instead of `.into_iter()` to avoid ambiguity: `iter`
@@ -36,7 +36,7 @@ LL |     [0u8; 33].into_iter();
    = note: for more information, see issue #66145 <https://github.com/rust-lang/rust/issues/66145>
 
 warning: this method call currently resolves to `<&[T; N] as IntoIterator>::into_iter` (due to autoref coercions), but that might change in the future when `IntoIterator` impls for arrays are added.
-  --> $DIR/into-iter-on-arrays-lint.rs:22:21
+  --> $DIR/into-iter-on-arrays-lint.rs:23:21
    |
 LL |     Box::new(small).into_iter();
    |                     ^^^^^^^^^ help: use `.iter()` instead of `.into_iter()` to avoid ambiguity: `iter`
@@ -45,7 +45,7 @@ LL |     Box::new(small).into_iter();
    = note: for more information, see issue #66145 <https://github.com/rust-lang/rust/issues/66145>
 
 warning: this method call currently resolves to `<&[T; N] as IntoIterator>::into_iter` (due to autoref coercions), but that might change in the future when `IntoIterator` impls for arrays are added.
-  --> $DIR/into-iter-on-arrays-lint.rs:25:22
+  --> $DIR/into-iter-on-arrays-lint.rs:26:22
    |
 LL |     Box::new([1, 2]).into_iter();
    |                      ^^^^^^^^^ help: use `.iter()` instead of `.into_iter()` to avoid ambiguity: `iter`
@@ -54,7 +54,7 @@ LL |     Box::new([1, 2]).into_iter();
    = note: for more information, see issue #66145 <https://github.com/rust-lang/rust/issues/66145>
 
 warning: this method call currently resolves to `<&[T; N] as IntoIterator>::into_iter` (due to autoref coercions), but that might change in the future when `IntoIterator` impls for arrays are added.
-  --> $DIR/into-iter-on-arrays-lint.rs:28:19
+  --> $DIR/into-iter-on-arrays-lint.rs:29:19
    |
 LL |     Box::new(big).into_iter();
    |                   ^^^^^^^^^ help: use `.iter()` instead of `.into_iter()` to avoid ambiguity: `iter`
@@ -63,7 +63,7 @@ LL |     Box::new(big).into_iter();
    = note: for more information, see issue #66145 <https://github.com/rust-lang/rust/issues/66145>
 
 warning: this method call currently resolves to `<&[T; N] as IntoIterator>::into_iter` (due to autoref coercions), but that might change in the future when `IntoIterator` impls for arrays are added.
-  --> $DIR/into-iter-on-arrays-lint.rs:31:25
+  --> $DIR/into-iter-on-arrays-lint.rs:32:25
    |
 LL |     Box::new([0u8; 33]).into_iter();
    |                         ^^^^^^^^^ help: use `.iter()` instead of `.into_iter()` to avoid ambiguity: `iter`
@@ -72,7 +72,7 @@ LL |     Box::new([0u8; 33]).into_iter();
    = note: for more information, see issue #66145 <https://github.com/rust-lang/rust/issues/66145>
 
 warning: this method call currently resolves to `<&[T; N] as IntoIterator>::into_iter` (due to autoref coercions), but that might change in the future when `IntoIterator` impls for arrays are added.
-  --> $DIR/into-iter-on-arrays-lint.rs:35:31
+  --> $DIR/into-iter-on-arrays-lint.rs:36:31
    |
 LL |     Box::new(Box::new(small)).into_iter();
    |                               ^^^^^^^^^ help: use `.iter()` instead of `.into_iter()` to avoid ambiguity: `iter`
@@ -81,7 +81,7 @@ LL |     Box::new(Box::new(small)).into_iter();
    = note: for more information, see issue #66145 <https://github.com/rust-lang/rust/issues/66145>
 
 warning: this method call currently resolves to `<&[T; N] as IntoIterator>::into_iter` (due to autoref coercions), but that might change in the future when `IntoIterator` impls for arrays are added.
-  --> $DIR/into-iter-on-arrays-lint.rs:38:32
+  --> $DIR/into-iter-on-arrays-lint.rs:39:32
    |
 LL |     Box::new(Box::new([1, 2])).into_iter();
    |                                ^^^^^^^^^ help: use `.iter()` instead of `.into_iter()` to avoid ambiguity: `iter`
@@ -90,7 +90,7 @@ LL |     Box::new(Box::new([1, 2])).into_iter();
    = note: for more information, see issue #66145 <https://github.com/rust-lang/rust/issues/66145>
 
 warning: this method call currently resolves to `<&[T; N] as IntoIterator>::into_iter` (due to autoref coercions), but that might change in the future when `IntoIterator` impls for arrays are added.
-  --> $DIR/into-iter-on-arrays-lint.rs:41:29
+  --> $DIR/into-iter-on-arrays-lint.rs:42:29
    |
 LL |     Box::new(Box::new(big)).into_iter();
    |                             ^^^^^^^^^ help: use `.iter()` instead of `.into_iter()` to avoid ambiguity: `iter`
@@ -99,7 +99,7 @@ LL |     Box::new(Box::new(big)).into_iter();
    = note: for more information, see issue #66145 <https://github.com/rust-lang/rust/issues/66145>
 
 warning: this method call currently resolves to `<&[T; N] as IntoIterator>::into_iter` (due to autoref coercions), but that might change in the future when `IntoIterator` impls for arrays are added.
-  --> $DIR/into-iter-on-arrays-lint.rs:44:35
+  --> $DIR/into-iter-on-arrays-lint.rs:45:35
    |
 LL |     Box::new(Box::new([0u8; 33])).into_iter();
    |                                   ^^^^^^^^^ help: use `.iter()` instead of `.into_iter()` to avoid ambiguity: `iter`

src/tools/compiletest/src/json.rs

@@ -36,6 +36,17 @@ struct DiagnosticSpan {
     expansion: Option<Box<DiagnosticSpanMacroExpansion>>,
 }
 
+#[derive(Deserialize)]
+struct FutureIncompatReport {
+    future_incompat_report: Vec<FutureBreakageItem>
+}
+
+#[derive(Deserialize)]
+struct FutureBreakageItem {
+    future_breakage_date: Option<String>,
+    diagnostic: Diagnostic
+}
+
 impl DiagnosticSpan {
     /// Returns the deepest source span in the macro call stack with a given file name.
     /// This is either the supplied span, or the span for some macro callsite that expanded to it.
@@ -94,10 +105,14 @@ pub fn extract_rendered(output: &str) -> String {
 }
 
 pub fn parse_output(file_name: &str, output: &str, proc_res: &ProcRes) -> Vec<Error> {
-    output.lines().flat_map(|line| parse_line(file_name, line, output, proc_res)).collect()
+    let lines = output.lines();
+    let last_line = lines.next_back();
+    lines.flat_map(|line| parse_line(file_name, line, output, proc_res, false)).chain(
+        last_line.into_iter().flat_map(|line| parse_line(file_name, line, output, proc_res, true))
+    ).collect()
 }
 
-fn parse_line(file_name: &str, line: &str, output: &str, proc_res: &ProcRes) -> Vec<Error> {
+fn parse_line(file_name: &str, line: &str, output: &str, proc_res: &ProcRes, last_line: bool) -> Vec<Error> {
     // The compiler sometimes intermingles non-JSON stuff into the
     // output.  This hack just skips over such lines. Yuck.
     if line.starts_with('{') {