1 files changed, 50 insertions, 0 deletions
diff --git a/src/test/ui/associated-types/cache/project-fn-ret-contravariant.rs b/src/test/ui/associated-types/cache/project-fn-ret-contravariant.rs
new file mode 100644
index 000000000..f1ea6627a
--- /dev/null
+++ b/src/test/ui/associated-types/cache/project-fn-ret-contravariant.rs
@@ -0,0 +1,50 @@
+#![feature(unboxed_closures)]
+
+// Test for projection cache. We should be able to project distinct
+// lifetimes from `foo` as we reinstantiate it multiple times, but not
+// if we do it just once. In this variant, the region `'a` is used in
+// an contravariant position, which affects the results.
+
+// revisions: ok oneuse transmute krisskross
+//[ok] check-pass
+//[oneuse] check-pass
+
+#![allow(dead_code, unused_variables)]
+
+fn foo<'a>() -> &'a u32 { loop { } }
+
+fn bar<T>(t: T, x: T::Output) -> T::Output
+    where T: FnOnce<()>
+{
+    t()
+}
+
+#[cfg(ok)] // two instantiations: OK
+fn baz<'a,'b>(x: &'a u32, y: &'b u32) -> (&'a u32, &'b u32) {
+    let a = bar(foo, x);
+    let b = bar(foo, y);
+    (a, b)
+}
+
+#[cfg(oneuse)] // one instantiation: OK (surprisingly)
+fn baz<'a,'b>(x: &'a u32, y: &'b u32) -> (&'a u32, &'b u32) {
+    let f /* : fn() -> &'static u32 */ = foo; // <-- inferred type annotated
+    let a = bar(f, x); // this is considered ok because fn args are contravariant...
+    let b = bar(f, y); // ...and hence we infer T to distinct values in each call.
+    (a, b)
+}
+
+#[cfg(transmute)] // one instantiations: BAD
+fn baz<'a,'b>(x: &'a u32) -> &'static u32 {
+   bar(foo, x) //[transmute]~ ERROR lifetime may not live long enough
+}
+
+#[cfg(krisskross)] // two instantiations, mixing and matching: BAD
+fn transmute<'a,'b>(x: &'a u32, y: &'b u32) -> (&'a u32, &'b u32) {
+   let a = bar(foo, y);
+   let b = bar(foo, x);
+   (a, b) //[krisskross]~ ERROR lifetime may not live long enough
+   //[krisskross]~^ ERROR lifetime may not live long enough
+}
+
+fn main() { }