Auto merge of #50739 - gnzlbg:vec_reserve, r=sfackler

Switch Vec from doubling size on growth to using RawVec's reserve

On growth, Vec does not require to exactly double its size for correctness,
like, for example, VecDeque does.

Using reserve instead better expresses this intent. It also allows to reuse
Excess capacity on growth and for better growth-policies to be provided by
RawVec.

r? @sfackler

1 files changed, 2 insertions, 2 deletions

diff --git a/src/liballoc/vec.rs b/src/liballoc/vec.rs
index bf89b377b7e..c48c64a8bef 100644
--- a/src/liballoc/vec.rs
+++ b/src/liballoc/vec.rs
@@ -837,7 +837,7 @@ impl<T> Vec<T> {
 
         // space for the new element
         if len == self.buf.cap() {
-            self.buf.double();
+            self.reserve(1);
         }
 
         unsafe {
@@ -1057,7 +1057,7 @@ impl<T> Vec<T> {
         // This will panic or abort if we would allocate > isize::MAX bytes
         // or if the length increment would overflow for zero-sized types.
         if self.len == self.buf.cap() {
-            self.buf.double();
+            self.reserve(1);
         }
         unsafe {
             let end = self.as_mut_ptr().offset(self.len as isize);