Auto merge of #101831 - compiler-errors:issue-75899, r=jackh726

Normalize struct field types in `confirm_builtin_unsize_candidate`

Fixes #75899

---

edited to move the normalization into `confirm_builtin_unsize_candidate` instead of the coercion code.

2 files changed, 39 insertions, 0 deletions

diff --git a/src/test/ui/unsized/issue-75899-but-gats.rs b/src/test/ui/unsized/issue-75899-but-gats.rs
new file mode 100644
index 00000000000..5716817f43d
--- /dev/null
+++ b/src/test/ui/unsized/issue-75899-but-gats.rs
@@ -0,0 +1,21 @@
+// check-pass
+
+use std::fmt::Debug;
+use std::marker::PhantomData;
+
+trait Foo {
+    type Gat<'a>: ?Sized where Self: 'a;
+}
+
+struct Bar<'a, T: Foo + 'a>(T::Gat<'a>);
+
+struct Baz<T: ?Sized>(PhantomData<T>);
+
+impl<T: ?Sized> Foo for Baz<T> {
+    type Gat<'a> = T where Self: 'a;
+}
+
+fn main() {
+    let x = Bar::<'_, Baz<()>>(());
+    let y: &Bar<'_, Baz<dyn Debug>> = &x;
+}
diff --git a/src/test/ui/unsized/issue-75899.rs b/src/test/ui/unsized/issue-75899.rs
new file mode 100644
index 00000000000..abff17e11b5
--- /dev/null
+++ b/src/test/ui/unsized/issue-75899.rs
@@ -0,0 +1,18 @@
+// check-pass
+
+trait Trait {}
+impl<T> Trait for T {}
+
+trait Noop {
+    type Assoc: ?Sized;
+}
+impl<T: ?Sized> Noop for T {
+    type Assoc = T;
+}
+
+struct NoopNewtype<T: ?Sized + Noop>(T::Assoc);
+fn coerce_newtype<T: Trait>(x: &NoopNewtype<T>) -> &NoopNewtype<dyn Trait + '_> {
+    x
+}
+
+fn main() {}