1 files changed, 32 insertions, 0 deletions
diff --git a/src/test/ui/nll/issue-53570.rs b/src/test/ui/nll/issue-53570.rs
new file mode 100644
index 000000000..35860ba9c
--- /dev/null
+++ b/src/test/ui/nll/issue-53570.rs
@@ -0,0 +1,32 @@
+// Regression test for #53570. Here, we need to propagate that `T: 'a`
+// but in some versions of NLL we were propagating a stronger
+// requirement that `T: 'static`. This arose because we actually had
+// to propagate both that `T: 'a` but also `T: 'b` where `'b` is the
+// higher-ranked lifetime that appears in the type of the closure
+// parameter `x` -- since `'b` cannot be expressed in the caller's
+// space, that got promoted th `'static`.
+//
+// check-pass
+
+use std::cell::{RefCell, Ref};
+
+trait AnyVec<'a> {
+}
+
+trait GenericVec<T> {
+    fn unwrap<'a, 'b>(vec: &'b dyn AnyVec<'a>) -> &'b [T] where T: 'a;
+}
+
+struct Scratchpad<'a> {
+    buffers: RefCell<Box<dyn AnyVec<'a>>>,
+}
+
+impl<'a> Scratchpad<'a> {
+    fn get<T: GenericVec<T>>(&self) -> Ref<[T]>
+    where T: 'a
+    {
+        Ref::map(self.buffers.borrow(), |x| T::unwrap(x.as_ref()))
+    }
+}
+
+fn main() { }