1 files changed, 44 insertions, 0 deletions
diff --git a/tests/ui/regions/regions-no-variance-from-fn-generics.rs b/tests/ui/regions/regions-no-variance-from-fn-generics.rs
new file mode 100644
index 000000000..76706a827
--- /dev/null
+++ b/tests/ui/regions/regions-no-variance-from-fn-generics.rs
@@ -0,0 +1,44 @@
+// run-pass
+#![allow(unused_variables)]
+// Issue #12856: a lifetime formal binding introduced by a generic fn
+// should not upset the variance inference for actual occurrences of
+// that lifetime in type expressions.
+
+
+pub trait HasLife<'a> {
+    fn dummy(&'a self) { } // just to induce a variance on 'a
+}
+
+trait UseLife01 {
+    fn refs<'a, H: HasLife<'a>>(&'a self) -> H;
+}
+
+trait UseLife02 {
+    fn refs<'a, T: 'a, H: HasType<&'a T>>(&'a self) -> H;
+}
+
+
+pub trait HasType<T>
+{
+    fn dummy(&self, t: T) -> T { panic!() }
+}
+
+
+trait UseLife03<T> {
+    fn refs<'a, H: HasType<&'a T>>(&'a self) -> H where T: 'a;
+}
+
+
+// (The functions below were not actually a problem observed during
+// fixing of #12856; they just seem like natural tests to put in to
+// cover a couple more points in the testing space)
+
+pub fn top_refs_1<'a, H: HasLife<'a>>(_s: &'a ()) -> H {
+    unimplemented!()
+}
+
+pub fn top_refs_2<'a, T: 'a, H: HasType<&'a T>>(_s: &'a ()) -> H {
+    unimplemented!()
+}
+
+pub fn main() {}