ldionne added a comment.
This is going to be really naive, but can someone explain why we need these
`__need_XXXXX` macros? Why doesn't `<stddef.h>` simply always declare what it
should declare? Also, does anybody understand the expected relationship between
the C Standard Library headers and these Clang builtin headers? Who defines
what?
Everyone I've spoken to so far about this (and myself) was extremely confused.
At some point I thought these macros were only needed for compatibility with
old glibcs but that wouldn't even be needed anymore, but I'm not certain.
================
Comment at: clang/lib/Headers/stddef.h:118-122
+#ifdef __cplusplus
+namespace std {
+typedef decltype(nullptr) nullptr_t;
+}
+using ::std::nullptr_t;
----------------
iana wrote:
> aaron.ballman wrote:
> > Related:
> >
> > https://github.com/llvm/llvm-project/issues/37564
> > https://cplusplus.github.io/LWG/issue3484
> >
> > CC @ldionne
> I don't _think_ this change actually changes the way nullptr_t gets defined
> in C++, does it?
I think we absolutely don't want to touch `std::nullptr_t` from this header.
It's libc++'s responsibility to define that, and in fact we define it in
`std::__1`, so this is even an ABI break (or I guess it would be a compiler
error, not sure).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D157757/new/
https://reviews.llvm.org/D157757
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