Add regression test for #132767 (try_normalize_erasing_regions ICE)

tests/ui/traits/ice-normalize-erasing-regions-132767.rs

@@ -0,0 +1,39 @@
+// Regression test for #132767
+// This used to ICE with "maybe try to call `try_normalize_erasing_regions`"
+// when using associated types with fn pointers and impl Trait.
+// Now it correctly reports a trait bound error.
+
+use std::hint::black_box;
+
+trait Func {
+    type Ret: Id;
+}
+trait Id {
+    type Assoc;
+}
+impl Id for i32 {
+    type Assoc = i32;
+}
+impl<F: FnOnce() -> R, R: Id> Func for F {
+    type Ret = R;
+}
+fn bar() -> impl Copy + Id {
+    //~^ ERROR the trait bound `u32: Id` is not satisfied
+    0u32
+}
+struct Foo<T: Func> {
+    _func: T,
+    value: Option<<<T as Func>::Ret as Id>::Assoc>,
+}
+fn main() {
+    let mut fn_def = black_box(Foo {
+        _func: bar,
+        value: None,
+    });
+    let fn_ptr = black_box(Foo {
+        _func: bar as fn() -> _,
+        value: None,
+    });
+    fn_def.value = fn_ptr.value;
+    black_box(fn_def);
+}

tests/ui/traits/ice-normalize-erasing-regions-132767.stderr

@@ -0,0 +1,18 @@
+error[E0277]: the trait bound `u32: Id` is not satisfied
+  --> $DIR/ice-normalize-erasing-regions-132767.rs:20:13
+   |
+LL | fn bar() -> impl Copy + Id {
+   |             ^^^^^^^^^^^^^^ the trait `Id` is not implemented for `u32`
+LL |
+LL |     0u32
+   |     ---- return type was inferred to be `u32` here
+   |
+help: the trait `Id` is implemented for `i32`
+  --> $DIR/ice-normalize-erasing-regions-132767.rs:14:1
+   |
+LL | impl Id for i32 {
+   | ^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0277`.