Add a regression test

Author: 0yoyoyo

src/test/ui/typeck/typeck_type_placeholder_item_help.rs

@@ -10,15 +10,18 @@ const TEST2: _ = 42u32;
 const TEST3: _ = Some(42);
 //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
 
-trait Test4 {
- const TEST4: _ = 42;
+const TEST4: fn() -> _ = 42;
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+
+trait Test5 {
+ const TEST5: _ = 42;
  //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
 }
 
-struct Test5;
+struct Test6;
 
-impl Test5 {
- const TEST5: _ = 13;
+impl Test6 {
+ const TEST6: _ = 13;
  //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
 }
 

src/test/ui/typeck/typeck_type_placeholder_item_help.stderr

@@ -26,23 +26,32 @@ LL | const TEST3: _ = Some(42);
  | help: replace `_` with the correct type: `Option<i32>`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
- --> $DIR/typeck_type_placeholder_item_help.rs:14:18
+ --> $DIR/typeck_type_placeholder_item_help.rs:13:22
  |
-LL | const TEST4: _ = 42;
+LL | const TEST4: fn() -> _ = 42;
+ | ^
+ | |
+ | not allowed in type signatures
+ | help: use type parameters instead: `T`
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+ --> $DIR/typeck_type_placeholder_item_help.rs:17:18
+ |
+LL | const TEST5: _ = 42;
  | ^
  | |
  | not allowed in type signatures
  | help: replace `_` with the correct type: `i32`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
- --> $DIR/typeck_type_placeholder_item_help.rs:21:18
+ --> $DIR/typeck_type_placeholder_item_help.rs:24:18
  |
-LL | const TEST5: _ = 13;
+LL | const TEST6: _ = 13;
  | ^
  | |
  | not allowed in type signatures
  | help: replace `_` with the correct type: `i32`
 
-error: aborting due to 5 previous errors
+error: aborting due to 6 previous errors
 
 For more information about this error, try `rustc --explain E0121`.