Use .copy_from_slice() where applicable

.copy_from_slice() does the same job of .clone_from_slice(), but the
former is explicitly for Copy elements and calls `memcpy` directly, and
thus is it efficient without optimization too.

2 files changed, 3 insertions, 2 deletions

diff --git a/src/libcoretest/lib.rs b/src/libcoretest/lib.rs
index f23ddea5cc9..e4df99002c8 100644
--- a/src/libcoretest/lib.rs
+++ b/src/libcoretest/lib.rs
@@ -15,6 +15,7 @@
 #![feature(box_syntax)]
 #![feature(cell_extras)]
 #![feature(const_fn)]
+#![feature(copy_from_slice)]
 #![feature(core_float)]
 #![feature(core_private_bignum)]
 #![feature(core_private_diy_float)]
diff --git a/src/libcoretest/num/flt2dec/mod.rs b/src/libcoretest/num/flt2dec/mod.rs
index 48a5501acb7..1a592f3ad42 100644
--- a/src/libcoretest/num/flt2dec/mod.rs
+++ b/src/libcoretest/num/flt2dec/mod.rs
@@ -100,7 +100,7 @@ fn check_exact<F, T>(mut f: F, v: T, vstr: &str, expected: &[u8], expectedk: i16
 
     // check significant digits
     for i in 1..cut.unwrap_or(expected.len() - 1) {
-        expected_[..i].clone_from_slice(&expected[..i]);
+        expected_[..i].copy_from_slice(&expected[..i]);
         let mut expectedk_ = expectedk;
         if expected[i] >= b'5' {
             // check if this is a rounding-to-even case.
@@ -147,7 +147,7 @@ fn check_exact<F, T>(mut f: F, v: T, vstr: &str, expected: &[u8], expectedk: i16
     // check infinite zero digits
     if let Some(cut) = cut {
         for i in cut..expected.len()-1 {
-            expected_[..cut].clone_from_slice(&expected[..cut]);
+            expected_[..cut].copy_from_slice(&expected[..cut]);
             for c in &mut expected_[cut..i] { *c = b'0'; }
 
             try_exact!(f(&decoded) => &mut buf, &expected_[..i], expectedk;