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Remove calls to mem::forget and mem::replace in Option::get_or_insert_with. #111301

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May 7, 2023
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Remove calls to mem::forget and mem::replace in Option::get_or_insert_with. #111301

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6 changes: 2 additions & 4 deletions library/core/src/option.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1641,10 +1641,8 @@ impl<T> Option<T> {
where
F: FnOnce() -> T,
{
if let None = *self {
// the compiler isn't smart enough to know that we are not dropping a `T`
// here and wants us to ensure `T` can be dropped at compile time.
mem::forget(mem::replace(self, Some(f())))
if let None = self {
*self = Some(f());
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This change makes sense to me, though -- the forget+replace is a residue from when this was unstably const, before that was undone.

}

// SAFETY: a `None` variant for `self` would have been replaced by a `Some`
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