Use $crate and macro reexport to reduce duplicated code

Many of libstd's macros are now re-exported from libcore and libcollections.
Their libstd definitions have moved to a macros_stage0 module and can disappear
after the next snapshot.

Where the two crates had already diverged, I took the libstd versions as
they're generally newer and better-tested. See e.g. d3c831b, which was a fix to
libstd's assert_eq!() that didn't make it into libcore's.

Fixes #16806.

2 files changed, 15 insertions, 0 deletions

diff --git a/src/libcollections/lib.rs b/src/libcollections/lib.rs
index db236795038..27ab791b604 100644
--- a/src/libcollections/lib.rs
+++ b/src/libcollections/lib.rs
@@ -51,6 +51,9 @@ pub use string::String;
 pub use vec::Vec;
 pub use vec_map::VecMap;
 
+// Needed for the vec! macro
+pub use alloc::boxed;
+
 mod macros;
 
 pub mod binary_heap;
diff --git a/src/libcollections/macros.rs b/src/libcollections/macros.rs
index ce4b1e46773..0dbc71269a6 100644
--- a/src/libcollections/macros.rs
+++ b/src/libcollections/macros.rs
@@ -11,6 +11,8 @@
 #![macro_escape]
 
 /// Creates a `std::vec::Vec` containing the arguments.
+// NOTE: remove after the next snapshot
+#[cfg(stage0)]
 macro_rules! vec {
     ($($e:expr),*) => ({
         // leading _ to allow empty construction without a warning.
@@ -21,3 +23,13 @@ macro_rules! vec {
     ($($e:expr),+,) => (vec!($($e),+))
 }
 
+/// Creates a `Vec` containing the arguments.
+#[cfg(not(stage0))]
+#[macro_export]
+macro_rules! vec {
+    ($($x:expr),*) => ({
+        let xs: $crate::boxed::Box<[_]> = box [$($x),*];
+        $crate::slice::SliceExt::into_vec(xs)
+    });
+    ($($x:expr,)*) => (vec![$($x),*])
+}