Short-circuit some variant constraints
#4966
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`variant`'s converting constructor and assignment operator templates are constrained to reject arguments of the `variant`'s type. In such a case, the templates instantiated to check the constructibility constraint might be ill-formed outside the immediate context of template instantiation causing a hard error. We should split the constraints into multiple `enable_if_t`s to enable short-circuiting of later constraints when the earlier constraints fail. Fixes microsoft#4959.
CaseyCarter
commented
Sep 19, 2024
barcharcraz
approved these changes
Sep 19, 2024
StephanTLavavej
requested changes
Sep 20, 2024
StephanTLavavej
approved these changes
Sep 20, 2024
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variant's converting constructor and assignment operator templates are constrained to reject arguments of thevariant's type. In such a case, the templates instantiated to check the constructibility constraint might be ill-formed outside the immediate context of template instantiation causing a hard error. We should split the constraints into multipleenable_if_ts to enable short-circuiting of later constraints when the earlier constraints fail.Fixes #4959.