[PATCH] D140250: Define NULL in its own header

Aaron Ballman via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Wed Jan 25 12:56:33 PST 2023


aaron.ballman added a comment.

In D140250#4081009 <https://reviews.llvm.org/D140250#4081009>, @iana wrote:

> In D140250#4080990 <https://reviews.llvm.org/D140250#4080990>, @rsmith wrote:
>
>> Wait a second... if an OS wants only `NULL`, we already have a supported way of achieving that, which is compatible with GCC and glibc and other POSIX compilers -- define `__need_NULL` before including the header.
>>
>> We shouldn't be providing internal headers with `__mangled_names` for OSes to include, those should be implementation details.
>
> You can't do that with modules though, `#define __need_NULL #include <stddef.h>` doesn't work.

Also, from the patch summary: ` i.e. in POSIX headers that are required to define NULL but not the rest of stddef.h.` -- I don't think `__need_NULL` works for this because it gets you `NULL` but it also gets you the rest of the stddef.h header, right?


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  https://reviews.llvm.org/D140250/new/

https://reviews.llvm.org/D140250



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