kc3-lang/gnulib/m4/nullptr.m4

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• Hash : 36f06b07
  Author :
  Date : 2023-02-09T17:09:23
  

  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.
  

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• m4/nullptr.m4

• # Check for nullptr that conforms to C23 and C++11.
  
  dnl Copyright 2023 Free Software Foundation, Inc.
  dnl This file is free software; the Free Software Foundation
  dnl gives unlimited permission to copy and/or distribute it,
  dnl with or without modifications, as long as this notice is preserved.
  
  AC_DEFUN([gl_NULLPTR],
  [
    m4_provide_if([AC_PROG_CC],
      [AC_LANG_PUSH([C])
       AC_CACHE_CHECK([for C nullptr], [gl_cv_c_nullptr],
         [AC_COMPILE_IFELSE(
            [AC_LANG_SOURCE([[int *p = nullptr;]])],
            [gl_cv_c_nullptr=yes],
            [gl_cv_c_nullptr=no])])
        gl_c_nullptr=$gl_cv_c_nullptr
        AC_LANG_POP([C])],
       [gl_c_nullptr=no])
    if test "$gl_c_nullptr" = yes; then
      AC_DEFINE([HAVE_C_NULLPTR], [1],
        [Define to 1 if C nullptr is known to work.])
    fi
  
    m4_provide_if([AC_PROG_CXX],
      [AC_LANG_PUSH([C++])
       AC_CACHE_CHECK([for C++ nullptr], [gl_cv_cxx_nullptr],
         [AC_COMPILE_IFELSE(
            [AC_LANG_SOURCE([[int *p = nullptr;]])],
            [gl_cv_cxx_nullptr=yes],
            [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([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 && HAVE_CXX_NULLPTR <= 0
  #  if 3 <= __GNUG__
  #   define nullptr __null
  #  else
  #   define nullptr 0L
  #  endif
  # endif
  #endif])
  ])
  

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