auto merge of #5410 : luqmana/rust/cfg-and, r=graydon

This adopts the syntax from #2119. No more annoying workarounds involving wrapping in mods!

src/test/compile-fail/test-cfg.rs

@@ -0,0 +1,18 @@
+// 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.
+
+// compile-flags: --cfg foo
+
+#[cfg(foo, bar)] // foo AND bar
+fn foo() {}
+
+fn main() {
+    foo(); //~ ERROR unresolved name: `foo`.
+}

src/test/run-pass/cfgs-on-items.rs

@@ -0,0 +1,31 @@
+// 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-fast
+// compile-flags: --cfg fooA --cfg fooB
+
+// fooA AND !bar
+#[cfg(fooA, not(bar))]
+fn foo1() -> int { 1 }
+
+// !fooA AND !bar
+#[cfg(not(fooA, bar))]
+fn foo2() -> int { 2 }
+
+// fooC OR (fooB AND !bar)
+#[cfg(fooC)]
+#[cfg(fooB, not(bar))]
+fn foo2() -> int { 3 }
+
+
+fn main() {
+    fail_unless!(1 == foo1());
+    fail_unless!(3 == foo2());
+}