Re: improving C++ libc headers

On 31 Jan 2024, at 05:03, Mark Millard <marklmi@yahoo.com> wrote:
> 
> Lexi Winter <lexi_at_le-fay.org> wrote on
> Date: Tue, 30 Jan 2024 13:30:54 UTC :
> 
>> i am considering working up a patch to improve C++ libc headers in FreeBSD.
>> 
>> the problem with the current headers (which come from clang/libc++) is
>> that this code compiles:
>> 
>> ------
>> #include <cstdlib>
>> auto main() -> int {
>> exit(0);
>> }
>> ------
>> 
>> this should be a compile-time error, because <cstdio> does not declare
>> ::exit[0]. however, it works because <cstdlib> is implemented like
>> this:
> 
> While I like the removal of header pollution, various
> C++ standard vintages have explicit wording that it is
> not an error for "C++ headers for C library facilities"
> (the for-C ones that are <c...> named) to be this way:
> 
> QUOTE of an example:
> It is unspecified whether these names (. . .) are first
> declared in the global namespace scope and are then
> injected into namespace std by explicit using-declarations.
> END QUOTE

Yeah, this is completely unrealistic, and will break a huge amount of
programs for little gain.

-Dimitry