<flat_map>: Restore use of push_back in flat_(multi)map::insert#5422
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StephanTLavavej merged 1 commit intomicrosoft:feature/flat_mapfrom Apr 21, 2025
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<flat_map>: Restore use of push_back in flat_(multi)map::insert`<flat_map>: Restore use of push_back in flat_(multi)map::insert
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Ah, I see, this is an optimization to avoid the general codepath for insert-at-end, it is not for correctness. |
StephanTLavavej
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Apr 21, 2025
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Thanks for figuring out how to combine performance with generality! 😸 |
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libc++ tests seem to use some hostile sequence containers whose
push_backhave non-standard semantics forflat_meow. Per [sequence.reqmts]/104 and /108, this is unfortunately permitted, becausepush_backwith the standard semantics is only required forbasic_string,deque,inplace_vector,list, andvector.AFAIK, most uses of flat container adaptors will use
vectoras the underlying containers. Also, every standard container adoptable forflat_meowhaspush_backwith guaranteed semantics. So I think it's worthy enablepush_backfor the most usual uses.Notes:
_Has_guaranteed_push_backforlistis deliberately missing becauselistisn't adoptable forflat_meow.inplace_vectoris not implemented yet so the partial specialization for it is missing.