Rollup merge of #45856 - estebank:issue-45829, r=nikomatsakis

Fix help for duplicated names: `extern crate (...) as (...)`

On the case of duplicated names caused by an `extern crate` statement
with a rename, don't include the inline suggestion, instead using a span
label with only the text to avoid incorrect rust code output.

Fix #45829.

src/test/compile-fail/E0259.rs

@@ -18,5 +18,6 @@ extern crate libc as alloc;
 //~^ ERROR E0259
 //~| NOTE `alloc` reimported here
 //~| NOTE `alloc` must be defined only once in the type namespace of this module
+//~| NOTE You can use `as` to change the binding name of the import
 
 fn main() {}

src/test/ui/suggestions/auxiliary/m1.rs

@@ -0,0 +1,11 @@
+// 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.
+
+pub fn foo() {}

src/test/ui/suggestions/auxiliary/m2.rs

@@ -0,0 +1,11 @@
+// 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.
+
+pub fn bar() {}

src/test/ui/suggestions/extern-crate-rename.rs

@@ -0,0 +1,18 @@
+// 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.
+
+// aux-build:m1.rs
+// aux-build:m2.rs
+
+
+extern crate m1;
+extern crate m2 as m1;
+
+fn main() {}

src/test/ui/suggestions/extern-crate-rename.stderr

@@ -0,0 +1,15 @@
+error[E0259]: the name `m1` is defined multiple times
+  --> $DIR/extern-crate-rename.rs:16:1
+   |
+15 | extern crate m1;
+   | ---------------- previous import of the extern crate `m1` here
+16 | extern crate m2 as m1;
+   | ^^^^^^^^^^^^^^^^^^^^^^
+   | |
+   | `m1` reimported here
+   | You can use `as` to change the binding name of the import
+   |
+   = note: `m1` must be defined only once in the type namespace of this module
+
+error: aborting due to previous error
+