[Clang] `__nullptr` isn't available in C

[philnik777]

C23 added nullptr as a keyword. C++ gained __nullptr as an extension a long time ago, but this isn't available in C for some reason. There doesn't seem much of a reason why it shouldn't be available in C.

[shafik]

CC @AaronBallman @erichkeane

[erichkeane]

The original commit that added __nullptr is here: 4aff944

It sadly doesn't have any real motivation nor review (for obvious reasons), but I would have no objection to exposing this. Its a 1-line change plus a test change (change ALIAS("__nullptr" , nullptr , KEYCXX) in TokenKinds.def to be KEYALL), so I'd be reasonably unopposed.

I DO have a hard time justifying the 'feature' at all, though I suspect at the time the theft of the keyword was meaningful here. I guess C is likely going through the same thing... All that to say, "this is weakly motivated for me, but since we're doing it in C++, I don't see the harm to doing it in C".

[llvmbot]

Hi!

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[llvmbot]

@llvm/issue-subscribers-good-first-issue

Author: Nikolas Klauser (philnik777)

C23 added `nullptr` as a keyword. C++ gained `__nullptr` as an extension a long time ago, but this isn't available in C for some reason. There doesn't seem much of a reason why it shouldn't be available in C.

[AidanGoldfarb]

I would be happy to take a look at this. Seems to be a simple enough change, but I can wait until there is some consensus on its necessity

[AaronBallman]

I would be happy to take a look at this. Seems to be a simple enough change, but I can wait until there is some consensus on its necessity

I think it's reasonable to add; it helps folks who might have their own uses of nullptr as an identifier but they want to migrate to C23.