Rollup merge of #62085 - JohnTitor:add-test-for-issue-38591, r=Centril

Add test for issue-38591

Closes #38591

r? @pnkfelix

src/test/ui/issues/issue-38591.rs

+// run-pass
+
+struct S<T> {
+    t : T,
+    s : Box<S<fn(u : T)>>
+}
+
+fn f(x : S<u32>) {}
+
+fn main () {}