1 files changed, 31 insertions, 0 deletions
diff --git a/tests/ui/traits/next-solver/equating-projection-cyclically.rs b/tests/ui/traits/next-solver/equating-projection-cyclically.rs
new file mode 100644
index 000000000..e7c80cfd7
--- /dev/null
+++ b/tests/ui/traits/next-solver/equating-projection-cyclically.rs
@@ -0,0 +1,31 @@
+// check-pass
+// compile-flags: -Znext-solver
+
+trait Test {
+    type Assoc;
+}
+
+fn transform<T: Test>(x: Inv<T>) -> Inv<T::Assoc> {
+    todo!()
+}
+
+impl Test for i32 {
+    type Assoc = i32;
+}
+
+impl Test for String {
+    type Assoc = String;
+}
+
+struct Inv<T>(Option<*mut T>);
+
+fn main() {
+    let mut x: Inv<_> = Inv(None);
+    // This ends up equating `Inv<?x>` with `Inv<<?x as Test>::Assoc>`
+    // which fails the occurs check when generalizing `?x`.
+    //
+    // We end up emitting a delayed obligation, causing this to still
+    // succeed.
+    x = transform(x);
+    x = Inv::<i32>(None);
+}