Address the review comments

src/librustc/middle/stability.rs

@@ -171,13 +171,6 @@ impl<'a, 'tcx: 'a> Annotator<'a, 'tcx> {
                     attr::mark_used(attr);
                     self.tcx.sess.span_err(attr.span(), "stability attributes may not be used \
                                                          outside of the standard library");
-                } else if tag == "deprecated" {
-                    if !self.tcx.sess.features.borrow().deprecated {
-                        self.tcx.sess.span_err(attr.span(),
-                                               "`#[deprecated]` attribute is unstable");
-                        fileline_help!(self.tcx.sess, attr.span(), "add #![feature(deprecated)] to \
-                                                                    the crate features to enable");
-                    }
                 }
             }
 
@@ -687,68 +680,20 @@ pub fn lookup_deprecation<'tcx>(tcx: &ty::ctxt<'tcx>, id: DefId) -> Option<Depre
 
 fn lookup_stability_uncached<'tcx>(tcx: &ty::ctxt<'tcx>, id: DefId) -> Option<&'tcx Stability> {
     debug!("lookup(id={:?})", id);
-
-    // is this definition the implementation of a trait method?
-    match tcx.trait_item_of_item(id) {
-        Some(ty::MethodTraitItemId(trait_method_id)) if trait_method_id != id => {
-            debug!("lookup: trait_method_id={:?}", trait_method_id);
-            return lookup_stability(tcx, trait_method_id)
-        }
-        _ => {}
-    }
-
-    let item_stab = if id.is_local() {
+    if id.is_local() {
         None // The stability cache is filled partially lazily
     } else {
         tcx.sess.cstore.stability(id).map(|st| tcx.intern_stability(st))
-    };
-
-    item_stab.or_else(|| {
-        if tcx.is_impl(id) {
-            if let Some(trait_id) = tcx.trait_id_of_impl(id) {
-                // FIXME (#18969): for the time being, simply use the
-                // stability of the trait to determine the stability of any
-                // unmarked impls for it. See FIXME above for more details.
-
-                debug!("lookup: trait_id={:?}", trait_id);
-                return lookup_stability(tcx, trait_id);
-            }
-        }
-        None
-    })
+    }
 }
 
 fn lookup_deprecation_uncached<'tcx>(tcx: &ty::ctxt<'tcx>, id: DefId) -> Option<Deprecation> {
     debug!("lookup(id={:?})", id);
-
-    // is this definition the implementation of a trait method?
-    match tcx.trait_item_of_item(id) {
-        Some(ty::MethodTraitItemId(trait_method_id)) if trait_method_id != id => {
-            debug!("lookup: trait_method_id={:?}", trait_method_id);
-            return lookup_deprecation(tcx, trait_method_id)
-        }
-        _ => {}
-    }
-
-    let item_depr = if id.is_local() {
+    if id.is_local() {
         None // The stability cache is filled partially lazily
     } else {
         tcx.sess.cstore.deprecation(id)
-    };
-
-    item_depr.or_else(|| {
-        if tcx.is_impl(id) {
-            if let Some(trait_id) = tcx.trait_id_of_impl(id) {
-                // FIXME (#18969): for the time being, simply use the
-                // stability of the trait to determine the stability of any
-                // unmarked impls for it. See FIXME above for more details.
-
-                debug!("lookup: trait_id={:?}", trait_id);
-                return lookup_deprecation(tcx, trait_id);
-            }
-        }
-        None
-    })
+    }
 }
 
 /// Given the list of enabled features that were not language features (i.e. that

src/librustc_lint/builtin.rs

@@ -575,7 +575,7 @@ impl LateLintPass for MissingDebugImplementations {
 declare_lint! {
     DEPRECATED,
     Warn,
-    "detects use of `#[deprecated]` or `#[rustc_deprecated]` items"
+    "detects use of deprecated items"
 }
 
 /// Checks for use of items with `#[deprecated]` or `#[rustc_deprecated]` attributes

src/libsyntax/feature_gate.rs

@@ -380,7 +380,7 @@ pub const KNOWN_ATTRIBUTES: &'static [(&'static str, AttributeType, AttributeGat
     ("must_use", Whitelisted, Ungated),
     ("stable", Whitelisted, Ungated),
     ("unstable", Whitelisted, Ungated),
-    ("deprecated", Whitelisted, Ungated),
+    ("deprecated", Normal, Gated("deprecated", "`#[deprecated]` attribute is unstable")),
 
     ("rustc_paren_sugar", Normal, Gated("unboxed_closures",
                                         "unboxed_closures are still evolving")),

src/test/auxiliary/deprecation-lint.rs

@@ -31,6 +31,9 @@ pub trait Trait {
     fn trait_deprecated_text(&self) {}
 }
 
+#[deprecated(since = "1.0.0", note = "text")]
+pub trait DeprecatedTrait { fn dummy(&self) { } }
+
 impl Trait for MethodTester {}
 
 #[deprecated(since = "1.0.0", note = "text")]

src/test/auxiliary/lint_stability.rs

@@ -98,6 +98,12 @@ impl Trait for MethodTester {}
 #[unstable(feature = "test_feature", issue = "0")]
 pub trait UnstableTrait { fn dummy(&self) { } }
 
+#[stable(feature = "test_feature", since = "1.0.0")]
+#[rustc_deprecated(since = "1.0.0", reason = "text")]
+pub trait DeprecatedTrait {
+    #[stable(feature = "test_feature", since = "1.0.0")] fn dummy(&self) { }
+}
+
 #[stable(feature = "test_feature", since = "1.0.0")]
 #[rustc_deprecated(since = "1.0.0", reason = "text")]
 pub struct DeprecatedStruct {

src/test/compile-fail/deprecation-lint.rs

@@ -78,6 +78,11 @@ mod cross_crate {
         foo.trait_deprecated_text(); //~ ERROR use of deprecated item: text
     }
 
+    struct S;
+
+    impl DeprecatedTrait for S {} //~ ERROR use of deprecated item: text
+    trait LocalTrait : DeprecatedTrait { } //~ ERROR use of deprecated item: text
+
     pub fn foo() {
         let x = Stable {
             override2: 3,

src/test/compile-fail/lint-stability.rs

@@ -227,8 +227,9 @@ mod cross_crate {
     struct S;
 
     impl UnstableTrait for S { } //~ ERROR use of unstable library feature
-
+    impl DeprecatedTrait for S {} //~ ERROR use of deprecated item: text
     trait LocalTrait : UnstableTrait { } //~ ERROR use of unstable library feature
+    trait LocalTrait2 : DeprecatedTrait { } //~ ERROR use of deprecated item: text
 
     impl Trait for S {
         fn trait_stable(&self) {}