On Thu, Apr 4, 2024 at 12:07 PM Jonathan Wakely <cxx_at_[hidden]> wrote:
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> On Thu, 4 Apr 2024, 16:59 Jonathan Wakely, <cxx_at_[hidden]> wrote:
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>> On Thu, 4 Apr 2024, 16:39 Aaron Ballman via Liaison, <liaison_at_[hidden]> wrote:
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>>> Also, I can't square how that fits with "The intended use of these
>>> headers is for interoperability only. It is possible that C++ source
>>> files need to include one of these headers in order to be valid ISO C.
>>> Source files that are not intended to also be valid ISO C should not
>>> use any of the C headers."
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>>> If it's for interoperability with valid ISO C... C23 is valid ISO C
>>> whether WG21 has rebased or not.
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>> But a common header that you expect to be used by both C and C++ code should generally stick to the common subset of the two languages. So don't use stdbit.h or assume unreachable is a macro.
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> I'm other words, "interoperability with ISO C" doesn't mean everything that's valid in the current C standard must also work in C++. That would be a very bizarre interpretation.
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> The current wording for the C headers is an attempt to improve what was there before, which said "these are deprecated, don't use them". It now says "these are here for interop with C, your don't need them otherwise". That's all it's trying to say. Please don't read between the lines to interpret it as "all valid C is valid C++". That's just silly. That's not the intention. If the intention is unclear, we can clarify it, but don't just assume silly intent.

Sorry, I'm really not aiming for silly intent, more just trying to
understand how to map that intent to an implementation that aims to
work with effectively arbitrary C standard libraries and this question
came up in those discussions.

~Aaron