[clang] Add __nullptr as a keyword to C

[AidanGoldfarb]

This PR resolves #121503.

I was not sure whether I added my test in the correct place, and if so, if that deprecates nullptr-98.cpp

[llvmbot]

@llvm/pr-subscribers-clang

Author: Aidan Goldfarb (AidanGoldfarb)

Changes

This PR resolves #121503.

I was not sure whether I added my test in the correct place, and if so, if that deprecates nullptr-98.cpp

---

Full diff: https://github.com/llvm/llvm-project/pull/123119.diff

2 Files Affected:

• (modified) clang/include/clang/Basic/TokenKinds.def (+1-1)
• (modified) clang/test/Sema/nullptr.c (+3)

diff --git a/clang/include/clang/Basic/TokenKinds.def b/clang/include/clang/Basic/TokenKinds.def
index 2c692c999bdff5..8902a20b07ffa8 100644
--- a/clang/include/clang/Basic/TokenKinds.def
+++ b/clang/include/clang/Basic/TokenKinds.def
@@ -707,7 +707,7 @@ ALIAS("__decltype"       , decltype     , KEYCXX)
 ALIAS("__imag__"         , __imag       , KEYALL)
 ALIAS("__inline"         , inline       , KEYALL)
 ALIAS("__inline__"       , inline       , KEYALL)
-ALIAS("__nullptr"        , nullptr      , KEYCXX)
+ALIAS("__nullptr"        , nullptr      , KEYALL)
 ALIAS("__real__"         , __real       , KEYALL)
 ALIAS("__restrict"       , restrict     , KEYALL)
 ALIAS("__restrict__"     , restrict     , KEYALL)
diff --git a/clang/test/Sema/nullptr.c b/clang/test/Sema/nullptr.c
index d11765a9c881a1..64095fc00691cd 100644
--- a/clang/test/Sema/nullptr.c
+++ b/clang/test/Sema/nullptr.c
@@ -108,3 +108,6 @@ void test_f1() {
   int ir = (f1)(nullptr);
 }
 
+// __nullptr keyword in C
+void foo(void *);
+void bar() { foo(__nullptr); }
\ No newline at end of file

[Sirraide]

Looking good overall, but this still needs a release note.

[Sirraide]

nit: missing newline at the end of the file

[AaronBallman]

Please be sure to also update clang/docs/ReleaseNotes.rst so users know about the new functionality. Also, not signing you up for this work, but we really should document all of these keywords in clang/docs/LanguageExtensions.rst. Maybe it's worth starting with this one and hopefully we can backfill the rest in the future?

[AidanGoldfarb]

Updating LanguageExtensions.rst before merge (and final reviews).

[AaronBallman]

LGTM aside from a change to the documentation. Thank you!