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Fix clippy lint suggestion incorrectly treated as `span_help`.

Author: estebank

clippy_lints/src/unnecessary_wraps.rs

@@ -145,7 +145,9 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryWraps {
                 (
                     "this function's return value is unnecessary".to_string(),
                     "remove the return type...".to_string(),
-                    snippet(cx, fn_decl.output.span(), "..").to_string(),
+                    // FIXME: we should instead get the span including the `->` and suggest an
+                    // empty string for this case.
+                    "()".to_string(),
                     "...and then remove returned values",
                 )
             } else {

tests/ui/unnecessary_literal_unwrap.stderr

@@ -63,7 +63,7 @@ LL |     let _val = None::<()>.expect("this always happens");
 help: remove the `None` and `expect()`
    |
 LL |     let _val = panic!("this always happens");
-   |                ~~~~~~~                     ~
+   |                ~~~~~~~
 
 error: used `unwrap_or_default()` on `None` value
   --> tests/ui/unnecessary_literal_unwrap.rs:22:24
@@ -134,7 +134,7 @@ LL |     None::<()>.expect("this always happens");
 help: remove the `None` and `expect()`
    |
 LL |     panic!("this always happens");
-   |     ~~~~~~~                     ~
+   |     ~~~~~~~
 
 error: used `unwrap_or_default()` on `None` value
   --> tests/ui/unnecessary_literal_unwrap.rs:30:5

tests/ui/unnecessary_wraps.stderr

@@ -118,8 +118,8 @@ LL | | }
    |
 help: remove the return type...
    |
-LL | fn issue_6640_1(a: bool, b: bool) -> Option<()> {
-   |                                      ~~~~~~~~~~
+LL | fn issue_6640_1(a: bool, b: bool) -> () {
+   |                                      ~~
 help: ...and then remove returned values
    |
 LL ~         return ;
@@ -145,8 +145,8 @@ LL | | }
    |
 help: remove the return type...
    |
-LL | fn issue_6640_2(a: bool, b: bool) -> Result<(), i32> {
-   |                                      ~~~~~~~~~~~~~~~
+LL | fn issue_6640_2(a: bool, b: bool) -> () {
+   |                                      ~~
 help: ...and then remove returned values
    |
 LL ~         return ;