Add a impl_stability gate test

Author: tiif

tests/ui/internal/auxiliary/unstable_feature.rs

@@ -1,6 +1,6 @@
-#![allow(internal_features)] // Enabled to use #![feature(staged_api)] and #![feature(impl_stability)]
-#![feature(staged_api)] // Enabled to use  #![unstable(feature = "feat_foo", issue = "none")]
-#![feature(impl_stability)] // Enabled to use #[unstable_feature_bound(feat_foo)] 
+#![allow(internal_features)]
+#![feature(staged_api)]
+#![feature(impl_stability)]
 #![allow(dead_code)]
 #![stable(feature = "a", since = "1.1.1" )]
 
@@ -13,14 +13,14 @@ pub trait Foo {
 pub struct Bar;
 
 // Annotate the impl as unstable.
-#[unstable_feature_bound(feat_foo)] 
+#[unstable_feature_bound(feat_foo)]
 #[unstable(feature = "feat_foo", issue = "none" )]
 impl Foo for Bar {
     fn foo() {}
 }
 
 // Use the unstable impl inside std/core.
-#[unstable_feature_bound(feat_foo)] 
+#[unstable_feature_bound(feat_foo)]
 fn bar() {
     Bar::foo();
 }

tests/ui/internal/unstable-feature-bound-gated.rs

@@ -0,0 +1,12 @@
+/// Test for impl_stability gate.
+
+trait Foo{}
+struct Bar;
+
+// TODO: make the error message below nicer
+#[unstable_feature_bound(feat_foo)]
+//~^ ERROR: allow unstable impl
+impl Foo for Bar{}
+
+fn main() {
+}

tests/ui/internal/unstable-feature-bound-gated.stderr

@@ -0,0 +1,12 @@
+error[E0658]: allow unstable impl
+  --> $DIR/unstable-feature-bound-gated.rs:7:1
+   |
+LL | #[unstable_feature_bound(feat_foo)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(impl_stability)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0658`.

tests/ui/internal/unstable-feature-bound-no-effect.rs

@@ -1,7 +1,7 @@
-#![allow(internal_features)] // Enabled to use #![feature(staged_api)] and #![feature(impl_stability)]
+#![allow(internal_features)]
 //~^ ERROR:  module has missing stability attribute
-#![feature(staged_api)] // Enabled to use  #![unstable(feature = "feat_foo", issue = "none")]
-#![feature(impl_stability)] // Enabled to use #[unstable_feature_bound(feat_foo)] 
+#![feature(staged_api)]
+#![feature(impl_stability)]
 #![allow(dead_code)]
 
 #[stable(feature = "a", since = "1.1.1" )]
@@ -13,7 +13,7 @@ pub struct Bar;
 
 
 // If #[unstable_feature_bound] and #[unstable] has different name,
-// It should throw an error. 
+// It should throw an error.
 #[unstable(feature = "feat_moo", issue = "none" )]
 #[unstable_feature_bound(feat_foo)] //~^ ERROR: an `#[unstable]` annotation here has no effect
 impl Moo for Bar {}
@@ -22,4 +22,4 @@ impl Moo for Bar {}
 #[unstable_feature_bound(feat_foo)]
 impl Foo for Bar {}
 
-fn main() {}
+fn main() {}

tests/ui/internal/unstable-feature-bound.rs

@@ -3,6 +3,6 @@
 extern crate unstable_feature;
 use unstable_feature::{Foo, Bar};
 
-fn main() { 
+fn main() {
     Bar::foo(); //~ ERROR: type annotations needed: cannot satisfy `unstable feature: `feat_foo``
-}
+}