Add test case for issue 7911

Author: jeremyletang

src/test/run-pass/issue-7911.rs

@@ -0,0 +1,48 @@
+// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// xfail-pretty
+
+// (Closes #7911) Test that we can use the same self expression 
+// with different mutability in macro in two methods
+
+#[allow(unused_variable)]; // unused foobar_immut + foobar_mut
+#[feature(macro_rules)];
+
+trait FooBar {}
+struct Bar(i32);
+struct Foo { bar: Bar }
+
+impl FooBar for Bar {}
+
+trait Test {
+    fn get_immut<'r>(&'r self) -> &'r FooBar;
+    fn get_mut<'r>(&'r mut self) -> &'r mut FooBar;
+}
+
+macro_rules! generate_test(($type_:path, $field:expr) => (
+    impl Test for $type_ {
+        fn get_immut<'r>(&'r self) -> &'r FooBar {
+            &$field as &FooBar
+        }
+
+        fn get_mut<'r>(&'r mut self) -> &'r mut FooBar {
+            &mut $field as &mut FooBar
+        }
+    }
+))
+
+generate_test!(Foo, self.bar)
+
+pub fn main() {
+    let mut foo: Foo = Foo { bar: Bar(42) };
+    { let foobar_immut = foo.get_immut(); }
+    { let foobar_mut = foo.get_mut(); }
+}