dnl A placeholder for <stddef.h>, for platforms that have issues.

# stddef_h.m4 serial 6

dnl Copyright (C) 2009-2020 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_STDDEF_H],

[

  AC_REQUIRE([gl_STDDEF_H_DEFAULTS])

  AC_REQUIRE([gt_TYPE_WCHAR_T])

  STDDEF_H=

  dnl Test whether the type max_align_t exists and whether its alignment

  dnl "is as great as is supported by the implementation in all contexts".

  AC_CACHE_CHECK([for good max_align_t],

    [gl_cv_type_max_align_t],

    [AC_COMPILE_IFELSE(

       [AC_LANG_PROGRAM(

          [[#include <stddef.h>

            unsigned int s = sizeof (max_align_t);

            #if defined __GNUC__ || defined __IBM__ALIGNOF__

            int check1[2 * (__alignof__ (double) <= __alignof__ (max_align_t)) - 1];

            int check2[2 * (__alignof__ (long double) <= __alignof__ (max_align_t)) - 1];

            #endif

          ]])],

       [gl_cv_type_max_align_t=yes],

       [gl_cv_type_max_align_t=no])

    ])

  if test $gl_cv_type_max_align_t = no; then

    HAVE_MAX_ALIGN_T=0

    STDDEF_H=stddef.h

  fi

  if test $gt_cv_c_wchar_t = no; then

    HAVE_WCHAR_T=0

    STDDEF_H=stddef.h

  fi

  AC_CACHE_CHECK([whether NULL can be used in arbitrary expressions],

    [gl_cv_decl_null_works],

    [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <stddef.h>

      int test[2 * (sizeof NULL == sizeof (void *)) -1];

]])],

      [gl_cv_decl_null_works=yes],

      [gl_cv_decl_null_works=no])])

  if test $gl_cv_decl_null_works = no; then

    REPLACE_NULL=1

    STDDEF_H=stddef.h

  fi

  AC_SUBST([STDDEF_H])

  AM_CONDITIONAL([GL_GENERATE_STDDEF_H], [test -n "$STDDEF_H"])

  if test -n "$STDDEF_H"; then

    gl_NEXT_HEADERS([stddef.h])

  fi

])

AC_DEFUN([gl_STDDEF_MODULE_INDICATOR],

[

  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.

  AC_REQUIRE([gl_STDDEF_H_DEFAULTS])

  gl_MODULE_INDICATOR_SET_VARIABLE([$1])

])

AC_DEFUN([gl_STDDEF_H_DEFAULTS],

[

  dnl Assume proper GNU behavior unless another module says otherwise.

  REPLACE_NULL=0;                AC_SUBST([REPLACE_NULL])

  HAVE_MAX_ALIGN_T=1;            AC_SUBST([HAVE_MAX_ALIGN_T])

  HAVE_WCHAR_T=1;                AC_SUBST([HAVE_WCHAR_T])

])