Improve error message when duplicate names for type and trait method

src/test/ui/trait-method-private.rs

@@ -0,0 +1,30 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+mod inner {
+    pub trait Bar {
+        fn method(&self);
+    }
+
+    pub struct Foo;
+
+    impl Foo {
+        fn method(&self) {}
+    }
+
+    impl Bar for Foo {
+        fn method(&self) {}
+    }
+}
+
+fn main() {
+    let foo = inner::Foo;
+    foo.method();
+}

src/test/ui/trait-method-private.stderr

@@ -0,0 +1,12 @@
+error[E0624]: method `method` is private
+  --> $DIR/trait-method-private.rs:29:9
+   |
+29 |     foo.method();
+   |         ^^^^^^
+   |
+   = help: items from traits can only be used if the trait is in scope
+   = note: the following trait is implemented but not in scope, perhaps add a `use` for it:
+           candidate #1: `use inner::Bar;`
+
+error: aborting due to previous error
+