Add new syntax extension fourcc!()

fourcc!() allows you to embed FourCC (or OSType) values that are
evaluated as u32 literals. It takes a 4-byte ASCII string and produces
the u32 resulting in interpreting those 4 bytes as a u32, using either
the platform-native endianness, or explicitly as big or little endian.

src/test/compile-fail/syntax-extension-fourcc-bad-len.rs

@@ -0,0 +1,14 @@
+// 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.
+
+fn main() {
+    let val = fourcc!("foo"); //~ ERROR string literal with len != 4 in fourcc!
+    let val2 = fourcc!("fooba"); //~ ERROR string literal with len != 4 in fourcc!
+}

src/test/compile-fail/syntax-extension-fourcc-invalid-endian.rs

@@ -0,0 +1,13 @@
+// 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.
+
+fn main() {
+    let val = fourcc!("foo ", bork); //~ ERROR invalid endian directive in fourcc!
+}

src/test/compile-fail/syntax-extension-fourcc-non-ascii-str.rs

@@ -0,0 +1,13 @@
+// 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.
+
+fn main() {
+    let v = fourcc!("fooλ"); //~ ERROR non-ascii string literal in fourcc!
+}

src/test/compile-fail/syntax-extension-fourcc-non-literal.rs

@@ -0,0 +1,13 @@
+// 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.
+
+fn main() {
+    let val = fourcc!(foo); //~ ERROR non-literal in fourcc!
+}

src/test/compile-fail/syntax-extension-fourcc-unsupported-literal.rs

@@ -0,0 +1,13 @@
+// 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.
+
+fn main() {
+    let val = fourcc!(45f); //~ ERROR unsupported literal in fourcc!
+}

src/test/run-pass/syntax-extension-fourcc.rs

@@ -0,0 +1,30 @@
+// 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.
+
+static static_val: u32 = fourcc!("foo ");
+static static_val_le: u32 = fourcc!("foo ", little);
+static static_val_be: u32 = fourcc!("foo ", big);
+
+fn main() {
+    let val = fourcc!("foo ");
+    let exp = if cfg!(target_endian = "big") { 0x666f6f20u32 } else { 0x206f6f66u32 };
+    assert_eq!(val, exp);
+
+    let val = fourcc!("foo ", big);
+    assert_eq!(val, 0x666f6f20u32);
+
+    let val = fourcc!("foo ", little);
+    assert_eq!(val, 0x206f6f66u32);
+
+    let exp = if cfg!(target_endian = "big") { 0x666f6f20u32 } else { 0x206f6f66u32 };
+    assert_eq!(static_val, exp);
+    assert_eq!(static_val_le, 0x206f6f66u32);
+    assert_eq!(static_val_be, 0x666f6f20u32);
+}