---

yaml
---
r: 172841
b: refs/heads/try
c: ad7e33e
h: refs/heads/master
i:
  172839: e846a86
v: v3

Author: Manishearth

[refs]

@@ -2,7 +2,7 @@
 refs/heads/master: 170c4399e614fe599c3d41306b3429ca8b3b68c6
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: 5b3cd3900ceda838f5798c30ab96ceb41f962534
-refs/heads/try: dd074ab4eedcb08ca8a1861fc1e62f125e23fa8b
+refs/heads/try: ad7e33efee023822bd63fa6f942c25582ef12a1e
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/dist-snap: ba4081a5a8573875fed17545846f6f6902c8ba8d
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596

branches/try/src/libcore/lib.rs

@@ -63,6 +63,7 @@
 #![feature(simd, unsafe_destructor, slicing_syntax)]
 #![feature(unboxed_closures)]
 #![allow(unknown_features)] #![feature(int_uint)]
+#![feature(on_unimplemented)]
 #![deny(missing_docs)]
 
 #[macro_use]

branches/try/src/librustc/middle/traits/error_reporting.rs

@@ -181,9 +181,8 @@ pub fn report_selection_error<'a, 'tcx>(infcx: &InferCtxt<'a, 'tcx>,
                         let custom_note = report_on_unimplemented(infcx, &*trait_ref.0,
                                                                   obligation.cause.span);
                         if let Some(s) = custom_note {
-                           infcx.tcx.sess.span_note(
-                                obligation.cause.span,
-                                s.as_slice());
+                           infcx.tcx.sess.span_note(obligation.cause.span,
+                                                    s.as_slice());
                         }
                     }
                 }

branches/try/src/libsyntax/feature_gate.rs

@@ -71,6 +71,7 @@ static KNOWN_FEATURES: &'static [(&'static str, Status)] = &[
     ("visible_private_types", Active),
     ("slicing_syntax", Active),
     ("box_syntax", Active),
+    ("on_unimplemented", Active),
 
     ("if_let", Accepted),
     ("while_let", Accepted),
@@ -249,6 +250,10 @@ impl<'a, 'v> Visitor<'v> for PostExpansionVisitor<'a> {
                 self.gate_feature("linkage", i.span,
                                   "the `linkage` attribute is experimental \
                                    and not portable across platforms")
+            } else if attr.name() == "rustc_on_unimplemented" {
+                self.gate_feature("on_unimplemented", i.span,
+                                  "the `#[rustc_on_unimplemented]` attribute \
+                                  is an experimental feature")
             }
         }
         match i.node {

branches/try/src/test/compile-fail/on-unimplemented-bad-anno.rs

@@ -9,7 +9,9 @@
 // except according to those terms.
 // ignore-tidy-linelength
 
-#[allow(unused)]
+#![feature(on_unimplemented)]
+
+#![allow(unused)]
 
 #[rustc_on_unimplemented = "test error `{Self}` with `{Bar}` `{Baz}` `{Quux}`"]
 trait Foo<Bar, Baz, Quux>{}

branches/try/src/test/compile-fail/on-unimplemented.rs

@@ -9,6 +9,8 @@
 // except according to those terms.
 // ignore-tidy-linelength
 
+#![feature(on_unimplemented)]
+
 #[rustc_on_unimplemented = "test error `{Self}` with `{Bar}` `{Baz}` `{Quux}`"]
 trait Foo<Bar, Baz, Quux>{}