+2023-02-09 Paul Eggert <eggert@cs.ucla.edu>
+
+ nullptr: work around Apple clang 14 issue
+ Problem reported by Bruno Haible in:
+ https://lists.gnu.org/r/bug-gnulib/2023-02/msg00098.html
+ * doc/gnulib.texi (nullptr): Document limitations better.
+ * m4/nullptr.m4 (gl_NULLPTR): Check for incompatibility of macOS
+ clang 14.0.0 (clang-1400.0.29.202), where <stddef.h> defines a
+ non-working nullptr macro.
+
2023-02-09 Bruno Haible <bruno@clisp.org>
math: Fix compilation error in C++ mode on macOS 12.5.
@item
On older platforms Gnulib cannot easily emulate @code{nullptr_t}, so
-null pointer type checking is more error prone, and @code{_Generic}
-expressions cannot reliably distinguish @code{nullptr}'s type from
-integer or @code{void *} types.
+null pointer type checking is more error prone. In C, @code{_Generic}
+expressions cannot reliably distinguish the type of @code{nullptr}
+from integer or @code{void *} types. C++ overloading has similar
+limitations.
@end itemize
@node static_assert
[AC_COMPILE_IFELSE(
[AC_LANG_SOURCE([[int *p = nullptr;]])],
[gl_cv_cxx_nullptr=yes],
- [gl_cv_cxx_nullptr=no])])
- gl_cxx_nullptr=$gl_cv_cxx_nullptr
- AC_LANG_POP([C++])],
- [gl_cxx_nullptr=no])
- if test "$gl_cxx_nullptr" = yes; then
- AC_DEFINE([HAVE_CXX_NULLPTR], [1], [Define to 1 if C++ nullptr works.])
- fi
+ [AC_COMPILE_IFELSE(
+ [AC_LANG_SOURCE([[#include <stddef.h>
+ int *p = nullptr;]])],
+ [gl_cv_cxx_nullptr="yes, but it is a <stddef.h> macro"],
+ [gl_cv_cxx_nullptr=no])])])
+ AS_CASE([$gl_cv_cxx_nullptr],
+ [yes], [gl_have_cxx_nullptr=1],
+ [yes*], [gl_have_cxx_nullptr="(-1)"],
+ [gl_have_cxx_nullptr=0])
+ AC_DEFINE_UNQUOTED([HAVE_CXX_NULLPTR], [$gl_have_cxx_nullptr],
+ [Define to 1 if C++ nullptr works, 0 if not,
+ (-1) if it is a <stddef.h> macro.])
+ AC_LANG_POP([C++])])
])
- AH_VERBATIM([nullptr],
-[#ifndef nullptr /* keep config.h idempotent */
+ AH_VERBATIM([zznullptr],
+[#if defined __cplusplus && HAVE_CXX_NULLPTR < 0
+# include <stddef.h>
+# undef/**/nullptr
+#endif
+#ifndef nullptr
# if !defined __cplusplus && !defined HAVE_C_NULLPTR
# define nullptr ((void *) 0)
-# elif defined __cplusplus && !defined HAVE_CXX_NULLPTR
+# elif defined __cplusplus && HAVE_CXX_NULLPTR <= 0
# if 3 <= __GNUG__
# define nullptr __null
# else