#45829 when a renamed import conflict with a previous import

src/librustc_resolve/lib.rs

@@ -4796,10 +4796,18 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
                 err.span_suggestion_with_applicability(
                     binding.span,
                     rename_msg,
-                    if snippet.ends_with(';') {
-                        format!("{} as {};", &snippet[..snippet.len() - 1], suggested_name)
+                    if snippet.contains(" as ") {
+                        format!(
+                            "{} as {}",
+                            &snippet[..snippet.find(" as ").unwrap()],
+                            suggested_name,
+                        )
                     } else {
-                        format!("{} as {}", snippet, suggested_name)
+                        if snippet.ends_with(';') {
+                            format!("{} as {};", &snippet[..snippet.len() - 1], suggested_name)
+                        } else {
+                            format!("{} as {}", snippet, suggested_name)
+                        }
                     },
                     Applicability::MachineApplicable,
                 );

src/test/ui/issues/issue-45829/auxiliary/issue_45829_a.rs

@@ -0,0 +1,11 @@
+// Copyright 2018 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 const FOO: usize = *&0;

src/test/ui/issues/issue-45829/auxiliary/issue_45829_b.rs

@@ -0,0 +1,11 @@
+// Copyright 2018 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 const FOO: usize = *&0;

src/test/ui/issues/issue-45829/rename-extern-vs-use.rs

@@ -0,0 +1,16 @@
+// Copyright 2018 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:issue_45829_b.rs
+
+use std;
+extern crate issue_45829_b as std;
+
+fn main() {}

src/test/ui/issues/issue-45829/rename-extern-vs-use.stderr

@@ -0,0 +1,27 @@
+error[E0259]: the name `std` is defined multiple times
+  --> $DIR/rename-extern-vs-use.rs:14:1
+   |
+LL | extern crate issue_45829_b as std;
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | |
+   | `std` reimported here
+   | You can use `as` to change the binding name of the import
+   |
+   = note: `std` must be defined only once in the type namespace of this module
+
+error[E0254]: the name `std` is defined multiple times
+  --> $DIR/rename-extern-vs-use.rs:13:5
+   |
+LL | use std;
+   |     ^^^ `std` reimported here
+   |
+   = note: `std` must be defined only once in the type namespace of this module
+help: You can use `as` to change the binding name of the import
+   |
+LL | use std as other_std;
+   |     ^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
+Some errors occurred: E0254, E0259.
+For more information about an error, try `rustc --explain E0254`.

src/test/ui/issues/issue-45829/rename-extern.rs

@@ -0,0 +1,17 @@
+// Copyright 2018 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:issue_45829_a.rs
+// aux-build:issue_45829_b.rs
+
+extern crate issue_45829_a;
+extern crate issue_45829_b as issue_45829_a;
+
+fn main() {}

src/test/ui/issues/issue-45829/rename-extern.stderr

@@ -0,0 +1,16 @@
+error[E0259]: the name `issue_45829_a` is defined multiple times
+  --> $DIR/rename-extern.rs:15:1
+   |
+LL | extern crate issue_45829_a;
+   | --------------------------- previous import of the extern crate `issue_45829_a` here
+LL | extern crate issue_45829_b as issue_45829_a;
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | |
+   | `issue_45829_a` reimported here
+   | You can use `as` to change the binding name of the import
+   |
+   = note: `issue_45829_a` must be defined only once in the type namespace of this module
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0259`.

src/test/ui/issues/issue-45829/rename-use-vs-extern.rs

@@ -0,0 +1,16 @@
+// Copyright 2018 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:issue_45829_b.rs
+
+extern crate issue_45829_b;
+use std as issue_45829_b;
+
+fn main() {}

src/test/ui/issues/issue-45829/rename-use-vs-extern.stderr

@@ -0,0 +1,17 @@
+error[E0254]: the name `issue_45829_b` is defined multiple times
+  --> $DIR/rename-use-vs-extern.rs:14:5
+   |
+LL | extern crate issue_45829_b;
+   | --------------------------- previous import of the extern crate `issue_45829_b` here
+LL | use std as issue_45829_b;
+   |     ^^^^^^^^^^^^^^^^^^^^ `issue_45829_b` reimported here
+   |
+   = note: `issue_45829_b` must be defined only once in the type namespace of this module
+help: You can use `as` to change the binding name of the import
+   |
+LL | use std as other_issue_45829_b;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0254`.

src/test/ui/issues/issue-45829/rename-with-path.rs

@@ -0,0 +1,13 @@
+// Copyright 2018 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.
+
+use std::{collections::HashMap as A, sync::Arc as A};
+
+fn main() {}

src/test/ui/issues/issue-45829/rename-with-path.stderr

@@ -0,0 +1,17 @@
+error[E0252]: the name `A` is defined multiple times
+  --> $DIR/rename-with-path.rs:11:38
+   |
+LL | use std::{collections::HashMap as A, sync::Arc as A};
+   |           -------------------------  ^^^^^^^^^^^^^^ `A` reimported here
+   |           |
+   |           previous import of the type `A` here
+   |
+   = note: `A` must be defined only once in the type namespace of this module
+help: You can use `as` to change the binding name of the import
+   |
+LL | use std::{collections::HashMap as A, sync::Arc as OtherA};
+   |                                      ^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0252`.

src/test/ui/issues/issue-45829/rename.rs

@@ -0,0 +1,16 @@
+// Copyright 2018 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.
+
+use core;
+use std as core;
+
+fn main() {
+    1 + 1;
+}

src/test/ui/issues/issue-45829/rename.stderr

@@ -0,0 +1,17 @@
+error[E0252]: the name `core` is defined multiple times
+  --> $DIR/rename.rs:12:5
+   |
+LL | use core;
+   |     ---- previous import of the module `core` here
+LL | use std as core;
+   |     ^^^^^^^^^^^ `core` reimported here
+   |
+   = note: `core` must be defined only once in the type namespace of this module
+help: You can use `as` to change the binding name of the import
+   |
+LL | use std as other_core;
+   |     ^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0252`.

src/test/ui/resolve/resolve-conflict-import-vs-extern-crate.stderr

@@ -7,8 +7,8 @@ LL | use std::slice as std; //~ ERROR the name `std` is defined multiple times
    = note: `std` must be defined only once in the type namespace of this module
 help: You can use `as` to change the binding name of the import
    |
-LL | use std::slice as std as other_std; //~ ERROR the name `std` is defined multiple times
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | use std::slice as other_std; //~ ERROR the name `std` is defined multiple times
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error