lint: do not warn unused parens around higher-ranked function pointers

Fixes #104397

1 files changed, 18 insertions, 0 deletions

diff --git a/src/test/ui/lint/unused/issue-104397.rs b/src/test/ui/lint/unused/issue-104397.rs
new file mode 100644
index 00000000000..94e15cd96bc
--- /dev/null
+++ b/src/test/ui/lint/unused/issue-104397.rs
@@ -0,0 +1,18 @@
+// check-pass
+
+#![warn(unused)]
+#![deny(warnings)]
+
+struct Inv<'a>(&'a mut &'a ());
+
+trait Trait {}
+impl Trait for for<'a> fn(Inv<'a>) {}
+
+fn with_bound()
+where
+    (for<'a> fn(Inv<'a>)): Trait,
+{}
+
+fn main() {
+    with_bound();
+}