1 files changed, 35 insertions, 0 deletions
diff --git a/tests/ui/regions/type-param-outlives-reempty-issue-74429.rs b/tests/ui/regions/type-param-outlives-reempty-issue-74429.rs
new file mode 100644
index 000000000..d463f311c
--- /dev/null
+++ b/tests/ui/regions/type-param-outlives-reempty-issue-74429.rs
@@ -0,0 +1,35 @@
+// Regression test for #74429, where we didn't think that a type parameter
+// outlived `ReEmpty`.
+
+// check-pass
+
+use std::marker::PhantomData;
+
+fn apply<T, F: FnOnce(T)>(_: T, _: F) {}
+
+#[derive(Clone, Copy)]
+struct Invariant<T> {
+    t: T,
+    p: PhantomData<fn(T) -> T>,
+}
+
+fn verify_reempty<T>(x: T) {
+    // r is inferred to have type `Invariant<&ReEmpty(U0) T>`
+    let r = Invariant { t: &x, p: PhantomData };
+    // Creates a new universe, all variables from now on are in `U1`, say.
+    let _: fn(&()) = |_| {};
+    // Closure parameter is of type `&ReEmpty(U1) T`, so the closure has an implied
+    // bound of `T: ReEmpty(U1)`
+    apply(&x, |_| {
+        // Requires `typeof(r)` is well-formed, i.e. `T: ReEmpty(U0)`. If we
+        // only have the implied bound from the closure parameter to use this
+        // requires `ReEmpty(U1): ReEmpty(U0)`, which isn't true so we reported
+        // an error.
+        //
+        // This doesn't happen any more because we ensure that `T: ReEmpty(U0)`
+        // is an implicit bound for all type parameters.
+        drop(r);
+    });
+}
+
+fn main() {}