<map>, <unordered_map>: Allow MapLike<K, V&> again#3660
Merged
StephanTLavavej merged 1 commit intomicrosoft:mainfrom Apr 20, 2023
Merged
<map>, <unordered_map>: Allow MapLike<K, V&> again#3660StephanTLavavej merged 1 commit intomicrosoft:mainfrom
<map>, <unordered_map>: Allow MapLike<K, V&> again#3660StephanTLavavej merged 1 commit intomicrosoft:mainfrom
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barcharcraz
approved these changes
Apr 20, 2023
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I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed. |
[associative.reqmts.general]/8 says that the rules applying to |
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I think the cross-references in [associative.reqmts.general] are swapped; it doesn't make sense to apply the |
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One of the changes that I pushed to #2436 was damaging - while map-like types can't tolerate references as key types, using references as mapped types appears to be permitted (by the Standard, libstdc++, and libc++), and there are 4 projects across vcpkg and Real World Code that are doing this.
Fortunately, we can fix this before changes stop flowing into VS 2022 17.7 Preview 2, so users will never be affected. I'm removing my bad
static_asserts, and adding test coverage to minimally verify that this scenario compiles.(I suppose we could instead assert that the mapped types aren't function types or void types, but I'd rather just drop it entirely. Such usage is extremely unlikely and will still be rejected, just with lengthy diagnostics.)