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Remove fast path in reallocation for same layout sizes #75621
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This is not documented though, is it? It least
grow
does not have a comment explaining the caller obligations.Looks like
new_size >= old_size
would have to be among those.There was a problem hiding this comment.
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It's a safety constraint, that
new_size
must be greater than or equal toold_size
. Ifold_size
is non-zero (was checked just before),new_size
can't be zero.There was a problem hiding this comment.
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I have a commit ready to be pushed, which cleans up the implementations and documentation of
AllocRef
a bit, so those things get more clear. Theunsafe
should be moved to line 217 instead. The match arm, wherelayout.size() == 0
does not needunsafe
at all.Uh oh!
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Right, my only comment is that this is an undocumented safety constraint -- at least when looking just at the grow function, and not at the entire file.
EDIT: well, there is a debug assertion. But the usual comment explaining to the caller what they have to uphold is missing.
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However, I didn't want to change implementations much in this PR because of the perf-run.
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This is stated in the safety-section of the trait.
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Oh I see... in GH I couldn't see that this is a trait impl. Sorry.
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No Problem!
In any case #75657 should make this more readable if you only read the code. :)