Add test case for single bound

Author: benschulz

tests/ui/lint/unused/unused-parens-false-positive-issue-143653.fixed

@@ -0,0 +1,12 @@
+//@ run-rustfix
+
+#![deny(unused_parens)]
+#![allow(warnings)]
+trait MyTrait {}
+
+fn foo(_: Box<dyn FnMut(&mut u32) -> &mut (dyn MyTrait) + Send + Sync>) {}
+
+//~v ERROR unnecessary parentheses around type
+fn bar(_: Box<dyn FnMut(&mut u32) -> &mut dyn MyTrait>) {}
+
+fn main() {}

tests/ui/lint/unused/unused-parens-false-positive-issue-143653.rs

@@ -1,9 +1,12 @@
-//@ check-pass
+//@ run-rustfix
 
 #![deny(unused_parens)]
 #![allow(warnings)]
 trait MyTrait {}
 
 fn foo(_: Box<dyn FnMut(&mut u32) -> &mut (dyn MyTrait) + Send + Sync>) {}
 
+//~v ERROR unnecessary parentheses around type
+fn bar(_: Box<dyn FnMut(&mut u32) -> &mut (dyn MyTrait)>) {}
+
 fn main() {}

tests/ui/lint/unused/unused-parens-false-positive-issue-143653.stderr

@@ -0,0 +1,19 @@
+error: unnecessary parentheses around type
+  --> $DIR/unused-parens-false-positive-issue-143653.rs:10:43
+   |
+LL | fn bar(_: Box<dyn FnMut(&mut u32) -> &mut (dyn MyTrait)>) {}
+   |                                           ^           ^
+   |
+note: the lint level is defined here
+  --> $DIR/unused-parens-false-positive-issue-143653.rs:3:9
+   |
+LL | #![deny(unused_parens)]
+   |         ^^^^^^^^^^^^^
+help: remove these parentheses
+   |
+LL - fn bar(_: Box<dyn FnMut(&mut u32) -> &mut (dyn MyTrait)>) {}
+LL + fn bar(_: Box<dyn FnMut(&mut u32) -> &mut dyn MyTrait>) {}
+   |
+
+error: aborting due to 1 previous error
+