1 files changed, 39 insertions, 0 deletions
diff --git a/tests/ui/nll/ty-outlives/ty-param-closure-approximate-lower-bound.rs b/tests/ui/nll/ty-outlives/ty-param-closure-approximate-lower-bound.rs
new file mode 100644
index 000000000..4d8380599
--- /dev/null
+++ b/tests/ui/nll/ty-outlives/ty-param-closure-approximate-lower-bound.rs
@@ -0,0 +1,39 @@
+// compile-flags:-Zverbose
+
+#![allow(warnings)]
+#![feature(rustc_attrs)]
+
+use std::cell::Cell;
+
+// Invoke in such a way that the callee knows:
+//
+// - 'a: 'x
+//
+// and it must prove that `T: 'x`. Callee passes along `T: 'a`.
+fn twice<'a, F, T>(v: Cell<&'a ()>, value: T, mut f: F)
+where
+    F: for<'x> FnMut(Option<Cell<&'a &'x ()>>, &T),
+{
+    f(None, &value);
+    f(None, &value);
+}
+
+#[rustc_regions]
+fn generic<T>(value: T) {
+    let cell = Cell::new(&());
+    twice(cell, value, |a, b| invoke(a, b));
+}
+
+#[rustc_regions]
+fn generic_fail<'a, T>(cell: Cell<&'a ()>, value: T) {
+    twice(cell, value, |a, b| invoke(a, b));
+    //~^ ERROR the parameter type `T` may not live long enough
+}
+
+fn invoke<'a, 'x, T>(x: Option<Cell<&'x &'a ()>>, y: &T)
+where
+    T: 'x,
+{
+}
+
+fn main() {}