Cleaned up some tests

Author: reddevilmidzy

tests/ui/borrowck/return-ref-to-temporary.rs

@@ -1,6 +1,7 @@
+//! regression test for issue https://github.com/rust-lang/rust/issues/46472
 fn bar<'a>() -> &'a mut u32 {
     &mut 4
     //~^ ERROR cannot return reference to temporary value [E0515]
 }
 
-fn main() { }
+fn main() {}

tests/ui/borrowck/return-ref-to-temporary.stderr

@@ -1,5 +1,5 @@
 error[E0515]: cannot return reference to temporary value
-  --> $DIR/issue-46472.rs:2:5
+  --> $DIR/return-ref-to-temporary.rs:3:5
    |
 LL |     &mut 4
    |     ^^^^^-

tests/ui/closures/closure-upvar-trait-caching.rs

@@ -7,8 +7,9 @@
 // reasonable examples) let to ambiguity errors about not being able
 // to infer sufficient type information.
 
-
 fn main() {
     let n = 0;
-    let it = Some(1_usize).into_iter().inspect(|_| {n;});
+    let it = Some(1_usize).into_iter().inspect(|_| {
+        n;
+    });
 }

tests/ui/closures/nested-closure-call.rs

@@ -1,4 +1,5 @@
+//! regression test for https://github.com/rust-lang/rust/issues/24779
 //@ run-pass
 fn main() {
-    assert_eq!((||||42)()(), 42);
+    assert_eq!((|| || 42)()(), 42);
 }

tests/ui/codegen/repeated-debug-opt-flags.rs

@@ -1,3 +1,4 @@
+//! regression test for https://github.com/rust-lang/rust/issues/24945
 //@ run-pass
 // This test is just checking that we continue to accept `-g -g -O -O`
 // as options to the compiler.

tests/ui/enum/enum-variant-no-field.rs

@@ -1,4 +1,7 @@
-enum Foo { Bar }
+//! regression test for https://github.com/rust-lang/rust/issues/23253
+enum Foo {
+    Bar,
+}
 
 fn main() {
     Foo::Bar.a;

tests/ui/enum/enum-variant-no-field.stderr

@@ -1,5 +1,5 @@
 error[E0609]: no field `a` on type `Foo`
-  --> $DIR/issue-23253.rs:4:14
+  --> $DIR/enum-variant-no-field.rs:7:14
    |
 LL |     Foo::Bar.a;
    |              ^ unknown field

tests/ui/enum/enum-with-uninhabited-variant.rs

@@ -1,11 +1,12 @@
+//! regression test for issue https://github.com/rust-lang/rust/issues/50442
 //@ run-pass
 #![allow(dead_code)]
 enum Void {}
 
 enum Foo {
     A(i32),
     B(Void),
-    C(i32)
+    C(i32),
 }
 
 fn main() {

tests/ui/expr/return-in-block-tuple.rs

@@ -1,6 +1,7 @@
+//! regression test for https://github.com/rust-lang/rust/issues/18110
 //@ run-pass
 #![allow(unreachable_code)]
 
 fn main() {
-    ({return},);
+    ({ return },);
 }

tests/ui/extern/extern-rust-trait-method.rs

@@ -1,3 +1,4 @@
+//! Regression test for https://github.com/rust-lang/rust/issues/19398
 //@ check-pass
 
 trait T {