Rollup merge of #80774 - LingMan:patch-1, r=nagisa

Fix safety comment

The size assertion in the comment was inverted compared to the code. After fixing that the implication that `(new_size >= old_size) => new_size != 0` still doesn't hold so explain why `old_size != 0` at this point.
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Yuki Okushi 2021-01-10 16:55:57 +09:00 committed by GitHub
commit d64356f06c
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@ -166,8 +166,9 @@ impl System {
match old_layout.size() {
0 => self.alloc_impl(new_layout, zeroed),
// SAFETY: `new_size` is non-zero as `old_size` is greater than or equal to `new_size`
// as required by safety conditions. Other conditions must be upheld by the caller
// SAFETY: `new_size` is non-zero as `new_size` is greater than or equal to `old_size`
// as required by safety conditions and the `old_size == 0` case was handled in the
// previous match arm. Other conditions must be upheld by the caller
old_size if old_layout.align() == new_layout.align() => unsafe {
let new_size = new_layout.size();