Auto merge of #46720 - estebank:issue-46302, r=nikomatsakis

Fix incorrect type mismatch label pointing at return type

CC #46302.

src/test/ui/break-while-condition.stderr

@@ -13,9 +13,6 @@ LL | |         };
 error[E0308]: mismatched types
   --> $DIR/break-while-condition.rs:26:13
    |
-LL |   fn main() {
-   |             - expected `()` because of default return type
-...
 LL | /             while false { //~ ERROR mismatched types
 LL | |                 break
 LL | |             }
@@ -27,9 +24,6 @@ LL | |             }
 error[E0308]: mismatched types
   --> $DIR/break-while-condition.rs:34:13
    |
-LL |   fn main() {
-   |             - expected `()` because of default return type
-...
 LL | /             while false { //~ ERROR mismatched types
 LL | |                 return
 LL | |             }

src/test/ui/issue-50585.stderr

@@ -1,8 +1,6 @@
 error[E0308]: mismatched types
   --> $DIR/issue-50585.rs:12:18
    |
-LL | fn main() {
-   |           - expected `()` because of default return type
 LL |     |y: Vec<[(); for x in 0..2 {}]>| {};
    |                  ^^^^^^^^^^^^^^^^ expected usize, found ()
    |

src/test/ui/suggestions/issue-46302.rs

@@ -0,0 +1,19 @@
+// 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.
+
+fn foo() {
+  let s = "abc";
+  let u: &str = if true { s[..2] } else { s };
+  //~^ ERROR mismatched types
+}
+
+fn main() {
+    foo();
+}

src/test/ui/suggestions/issue-46302.stderr

@@ -0,0 +1,15 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-46302.rs:13:27
+   |
+LL |   let u: &str = if true { s[..2] } else { s };
+   |                           ^^^^^^
+   |                           |
+   |                           expected &str, found str
+   |                           help: consider borrowing here: `&s[..2]`
+   |
+   = note: expected type `&str`
+              found type `str`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.

src/test/ui/suggestions/str-array-assignment.stderr

@@ -10,9 +10,6 @@ LL |   let t = if true { s[..2] } else { s };
 error[E0308]: mismatched types
   --> $DIR/str-array-assignment.rs:15:27
    |
-LL | fn main() {
-   |           - expected `()` because of default return type
-...
 LL |   let u: &str = if true { s[..2] } else { s };
    |                           ^^^^^^
    |                           |