Export vec!() from libcollections

Fixes #16806. The duplication of code with libstd is unfortunate, but there's
already a lot of that exported from core::macros.

Author: Keegan McAllister

src/libcollections/lib.rs

@@ -574,4 +574,5 @@ mod std {
 mod collections {
     pub use hash;     // deriving(Hsah)
     pub use string;   // format!()
+    pub use vec;      // vec!()
 }

src/libcollections/macros.rs

@@ -11,10 +11,11 @@
 #![macro_escape]
 
 /// Creates a `std::vec::Vec` containing the arguments.
+#[macro_export]
 macro_rules! vec(
     ($($e:expr),*) => ({
         // leading _ to allow empty construction without a warning.
-        let mut _temp = ::vec::Vec::new();
+        let mut _temp = ::collections::vec::Vec::new();
         $(_temp.push($e);)*
         _temp
     });

src/test/run-pass/vec-macro-no-std.rs

@@ -0,0 +1,34 @@
+// Copyright 2014 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.
+
+#![feature(phase)]
+#![no_std]
+
+#[phase(plugin, link)]
+extern crate core;
+
+#[phase(plugin, link)]
+extern crate collections;
+
+extern crate native;
+
+use core::option::Some;
+use collections::vec::Vec;
+use collections::MutableSeq;
+
+// Issue #16806
+
+fn main() {
+    let x: Vec<u8> = vec!(0, 1, 2);
+    match x.last() {
+        Some(&2) => (),
+        _ => fail!(),
+    }
+}