More tests wrt #2263.

Author: lkuper

src/test/compile-fail/regions-fn-subtyping.rs

@@ -0,0 +1,21 @@
+// Issue #2263.
+
+// Here, `f` is a function that takes a pointer `x` and a function
+// `g`, where `g` requires its argument `y` to be in the same region
+// that `x` is in.
+fn has_same_region(f: fn(x: &a.int, g: fn(y: &a.int))) {
+    // Somewhat counterintuitively, this fails because, in
+    // `wants_two_regions`, the `g` argument needs to be able to
+    // accept any region.  That is, the type that `has_same_region`
+    // expects is *not* a subtype of the type that `wants_two_regions`
+    // expects.
+    wants_two_regions(f); //! ERROR mismatched types
+}
+
+fn wants_two_regions(_f: fn(x: &int, g: fn(y: &int))) {
+}
+
+fn main() {
+}
+
+

src/test/run-pass/regions-fn-subtyping-2.rs

@@ -0,0 +1,20 @@
+// xfail-test
+
+// Issue #2263.
+
+// Here, `f` is a function that takes a pointer `x` and a function
+// `g`, where `g` requires its argument `y` to be in the same region
+// that `x` is in.
+fn has_same_region(f: fn(x: &a.int, g: fn(y: &a.int))) {
+    // `f` should be the type that `wants_same_region` wants, but
+    // right now the compiler complains that it isn't.
+    wants_same_region(f);
+}
+
+fn wants_same_region(_f: fn(x: &b.int, g: fn(y: &b.int))) { 
+}
+
+fn main() {
+}
+
+