test our some of the various combinations of fn subtyping

Author: nikomatsakis

src/test/compile-fail/pure-subtyping.rs

@@ -18,5 +18,19 @@ fn assign_to_unsafe(x: pure fn(), y: fn(), z: unsafe fn()) {
     let o: unsafe fn() = z;
 }
 
+fn assign_to_pure2(x: pure fn@(), y: fn@(), z: unsafe fn@()) {
+    let a: pure fn() = x;
+    let b: pure fn() = y; //! ERROR expected pure fn but found impure fn
+    let c: pure fn() = z; //! ERROR expected pure fn but found unsafe fn
+
+    let a: pure fn~() = x; //! ERROR closure protocol mismatch (fn~ vs fn@)
+    let b: pure fn~() = y; //! ERROR closure protocol mismatch (fn~ vs fn@)
+    let c: pure fn~() = z; //! ERROR closure protocol mismatch (fn~ vs fn@)
+
+    let a: unsafe fn~() = x; //! ERROR closure protocol mismatch (fn~ vs fn@)
+    let b: unsafe fn~() = y; //! ERROR closure protocol mismatch (fn~ vs fn@)
+    let c: unsafe fn~() = z; //! ERROR closure protocol mismatch (fn~ vs fn@)
+}
+
 fn main() {
 }