Auto merge of #13464 - y21:issue13458, r=flip1995

Don't warn on proc macro generated code in `needless_return`

Fixes #13458
Fixes #13457
Fixes #13467
Fixes #13479
Fixes #13481
Fixes #13526
Fixes #13486

The fix is unfortunately a little more convoluted than just simply adding a `is_from_proc_macro`. That check *does*  fix the issue, however it also introduces a bunch of false negatives in the tests, specifically when the returned expression is in a different syntax context, e.g. `return format!(..)`.

The proc macro check builds up a start and end pattern based on the HIR nodes and compares it to a snippet of the span, however that would currently fail for `return format!(..)` because we would have the patterns `("return", <something inside of the format macro>)`, which doesn't compare equal. So we now return an empty string pattern for when it's in a different syntax context.

"Hide whitespace" helps a bit for reviewing the proc macro detection change

changelog: none

clippy_lints/src/returns.rs

@@ -407,7 +407,7 @@ fn check_final_expr<'tcx>(
                 }
             }
 
-            if ret_span.from_expansion() {
+            if ret_span.from_expansion() || is_from_proc_macro(cx, expr) {
                 return;
             }