llvm-project/clang/test/Headers/ms-null-ms-header-vs-stddef.cpp

// RUN: %clang_cc1 -fsyntax-only -triple i686-pc-win32 -fms-compatibility -fms-compatibility-version=17.00 %s
// RUN: %clang_cc1 -fsyntax-only -triple i386-mingw32 %s

// Something in MSVC's headers (pulled in e.g. by <crtdefs.h>) defines __null
// to something, mimic that.
#define __null

#include <stddef.h>

// __null is used as a type annotation in MS headers, with __null defined to
// nothing in regular builds. This should continue to work even with stddef.h
// included.
void f(__null void* p) { }

// NULL should work fine even with __null defined to nothing.
void* p = NULL;