More Mut tests

src/libstd/mutable.rs

@@ -295,4 +295,13 @@ mod test {
         let _b = x.borrow();
         x.with_mut(|x| *x += 1);
     }
+
+    #[test]
+    #[should_fail]
+    fn discard_doesnt_unborrow() {
+        let x = Mut::new(0);
+        let _b = x.borrow();
+        let _ = _b;
+        let _b = x.borrow_mut();
+    }
 }

src/test/compile-fail/mut-cant-alias.rs

@@ -0,0 +1,18 @@
+// Copyright 2013 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.
+
+use std::mutable::Mut;
+
+fn main() {
+    let m = Mut::new(0);
+    let mut b = m.borrow_mut();
+    let b1 = b.get();
+    let b2 = b.get(); //~ ERROR cannot borrow `b` as mutable more than once at a time
+}

src/test/compile-fail/mut-ptr-cant-outlive-ref.rs

@@ -0,0 +1,20 @@
+// Copyright 2013 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.
+
+use std::mutable::Mut;
+
+fn main() {
+    let m = Mut::new(0);
+    let p;
+    {
+        let b = m.borrow();
+        p = b.get(); //~ ERROR borrowed value does not live long enough
+    }
+}