1 files changed, 64 insertions, 0 deletions
diff --git a/src/test/ui/associated-types/cache/project-fn-ret-invariant.rs b/src/test/ui/associated-types/cache/project-fn-ret-invariant.rs
new file mode 100644
index 000000000..1075fd6e0
--- /dev/null
+++ b/src/test/ui/associated-types/cache/project-fn-ret-invariant.rs
@@ -0,0 +1,64 @@
+#![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 invariant position, which affects the results.
+
+// revisions: ok oneuse transmute krisskross
+//[ok] check-pass
+
+#![allow(dead_code, unused_variables)]
+
+use std::marker::PhantomData;
+
+struct Type<'a> {
+    // Invariant
+    data: PhantomData<fn(&'a u32) -> &'a u32>,
+}
+
+fn foo<'a>() -> Type<'a> {
+    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: Type<'a>, y: Type<'b>) -> (Type<'a>, Type<'b>) {
+    let a = bar(foo, x);
+    let b = bar(foo, y);
+    (a, b)
+}
+
+#[cfg(oneuse)] // one instantiation: BAD
+fn baz<'a, 'b>(x: Type<'a>, y: Type<'b>) -> (Type<'a>, Type<'b>) {
+    let f = foo; // <-- No consistent type can be inferred for `f` here.
+    let a = bar(f, x);
+    //[oneuse]~^ ERROR lifetime may not live long enough
+    //[oneuse]~| ERROR lifetime may not live long enough
+    let b = bar(f, y);
+    (a, b)
+}
+
+#[cfg(transmute)] // one instantiations: BAD
+fn baz<'a, 'b>(x: Type<'a>) -> Type<'static> {
+    // Cannot instantiate `foo` with any lifetime other than `'a`,
+    // since it is provided as input.
+
+    bar(foo, x) //[transmute]~ ERROR lifetime may not live long enough
+}
+
+#[cfg(krisskross)] // two instantiations, mixing and matching: BAD
+fn transmute<'a, 'b>(x: Type<'a>, y: Type<'b>) -> (Type<'a>, Type<'b>) {
+    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() {}