1 files changed, 53 insertions, 0 deletions
diff --git a/src/test/ui/nll/ty-outlives/ty-param-closure-outlives-from-return-type.rs b/src/test/ui/nll/ty-outlives/ty-param-closure-outlives-from-return-type.rs
new file mode 100644
index 000000000..4343c3aee
--- /dev/null
+++ b/src/test/ui/nll/ty-outlives/ty-param-closure-outlives-from-return-type.rs
@@ -0,0 +1,53 @@
+// compile-flags:-Zverbose
+
+#![allow(warnings)]
+#![feature(rustc_attrs)]
+
+use std::fmt::Debug;
+
+fn with_signature<'a, T, F>(x: Box<T>, op: F) -> Box<dyn Debug + 'a>
+    where F: FnOnce(Box<T>) -> Box<dyn Debug + 'a>
+{
+    op(x)
+}
+
+#[rustc_regions]
+fn no_region<'a, T>(x: Box<T>) -> Box<dyn Debug + 'a>
+where
+    T: Debug,
+{
+    // Here, the closure winds up being required to prove that `T:
+    // 'a`.  In principle, it could know that, except that it is
+    // type-checked in a fully generic way, and hence it winds up with
+    // a propagated requirement that `T: '_#2`, where `'_#2` appears
+    // in the return type. The caller makes the mapping from `'_#2` to
+    // `'a` (and subsequently reports an error).
+
+    with_signature(x, |y| y)
+    //~^ ERROR the parameter type `T` may not live long enough
+}
+
+fn correct_region<'a, T>(x: Box<T>) -> Box<Debug + 'a>
+where
+    T: 'a + Debug,
+{
+    x
+}
+
+fn wrong_region<'a, 'b, T>(x: Box<T>) -> Box<Debug + 'a>
+where
+    T: 'b + Debug,
+{
+    x
+    //~^ ERROR the parameter type `T` may not live long enough
+}
+
+fn outlives_region<'a, 'b, T>(x: Box<T>) -> Box<Debug + 'a>
+where
+    T: 'b + Debug,
+    'b: 'a,
+{
+    x
+}
+
+fn main() {}