add test for #90192

Fixes #90192

Author: matthiaskrgr

tests/ui/polymorphization/ice-poly-with-mir-opts-90192.rs

@@ -0,0 +1,20 @@
+// issue: rust-lang/rust#90192
+// ICE assertion failed: matches!(ty.kind(), ty :: Param(_))
+//@ compile-flags:-Zpolymorphize=on -Zmir-opt-level=3
+//@ build-pass
+
+fn test<T>() {
+    std::mem::size_of::<T>();
+}
+
+pub fn foo<T>(_: T) -> &'static fn() {
+    &(test::<T> as fn())
+}
+
+fn outer<T>() {
+    foo(|| ());
+}
+
+fn main() {
+    outer::<u8>();
+}