Yuki Okushi 290117f7d9
Rollup merge of #82564 - WaffleLapkin:revert_spare_mut, r=RalfJung
Revert `Vec::spare_capacity_mut` impl to prevent pointers invalidation

The implementation was changed in #79015.

Later it was [pointed out](https://github.com/rust-lang/rust/issues/81944#issuecomment-782849785) that the implementation invalidates pointers to the buffer (initialized elements) by creating a unique reference to the buffer. This PR reverts the implementation.

r? ```@RalfJung```
2021-03-04 20:01:06 +09:00
..
2021-02-20 17:19:30 -05:00
2020-12-02 14:09:36 +01:00
2020-12-13 10:21:24 +01:00