Tweak typecheck to enforce covariance on higher-order function arguments

1 files changed, 14 insertions, 0 deletions

diff --git a/src/test/compile-fail/block-coerce-no-2.rs b/src/test/compile-fail/block-coerce-no-2.rs
new file mode 100644
index 00000000000..926e39529ea
--- /dev/null
+++ b/src/test/compile-fail/block-coerce-no-2.rs
@@ -0,0 +1,14 @@
+// error-pattern: mismatched types
+
+// Make sure that fn-to-block coercion isn't incorrectly lifted over
+// other tycons.
+
+fn main() {
+    fn f(f: fn(fn(fn()))) {
+    }
+
+    fn g(f: fn(block())) {
+    }
+
+    f(g);
+}