Add high-priority ICE: 150263

tests/crashes/150263.rs

@@ -0,0 +1,21 @@
+//@ known-bug: #150263
+//@ compile-flags: --crate-type lib
+
+pub trait Scope {
+    type Timestamp;
+}
+impl<G> Scope for G {
+    type Timestamp = ();
+}
+
+pub fn create<G: Scope>() {
+    enter::<G>();
+}
+
+fn enter<G>() {
+    unary::<G>(|_: <G as Scope>::Timestamp| {});
+}
+
+fn unary<G: Scope>(constructor: impl FnOnce(G::Timestamp)) {
+    constructor(None.unwrap());
+}