std: use a match in assert_eq! to extend the lifetime of the args.

This enables

    assert_eq!(foo.collect::<Vec<...>>().as_slice(), &[1,2,3,4]);

to work, by extending the lifetime of the .as_slice() rvalue.

Author: huonw

src/libstd/macros.rs

@@ -117,13 +117,15 @@ macro_rules! assert(
 #[macro_export]
 macro_rules! assert_eq(
     ($given:expr , $expected:expr) => ({
-        let given_val = &($given);
-        let expected_val = &($expected);
-        // check both directions of equality....
-        if !((*given_val == *expected_val) &&
-             (*expected_val == *given_val)) {
-            fail!("assertion failed: `(left == right) && (right == left)` \
-                   (left: `{}`, right: `{}`)", *given_val, *expected_val)
+        match (&($given), &($expected)) {
+            (given_val, expected_val) => {
+                // check both directions of equality....
+                if !((*given_val == *expected_val) &&
+                     (*expected_val == *given_val)) {
+                    fail!("assertion failed: `(left == right) && (right == left)` \
+                           (left: `{}`, right: `{}`)", *given_val, *expected_val)
+                }
+            }
         }
     })
 )