add regression test

tests/ui/layout/rigid-alias-no-params.rs

@@ -0,0 +1,30 @@
+//@ compile-flags: -O -Cdebug-assertions=on
+//@ build-pass
+
+// A regression test for #151791. Computing the layout of
+// `<AsOwned as ArchiveWith<'a>>::Archived` fails as the alias
+// is still rigid as the where-bound in scope shadows the impl.
+//
+// This previously caused an incorrect error during MIR optimizations.
+
+struct ArchivedString;
+
+pub trait ArchiveWith<'a> {
+    type Archived;
+}
+
+struct AsOwned;
+impl ArchiveWith<'_> for AsOwned {
+    type Archived = ArchivedString;
+}
+
+fn foo<'a>()
+where
+    AsOwned: ArchiveWith<'a>,
+{
+    let _ = unsafe { &*std::ptr::dangling::<<AsOwned as ArchiveWith<'a>>::Archived>() };
+}
+
+fn main() {
+    foo();
+}

tests/ui/where-clauses/projection-bound-unsatisfied-item-bounds-mit-opt-ice.rs

@@ -2,7 +2,7 @@
 //@ build-pass
 
 // A regression test for #149081. The environment of `size` and `align`
-// currently means that the item bound of`T::Assoc` doesn't hold. This can
+// currently means that the item bound of `T::Assoc` doesn't hold. This can
 // result in normalization failures and ICE during MIR optimizations.
 //
 // This will no longer be an issue once #149283 is implemented.