m4/stdbool.m4

# Check for stdbool.h that conforms to C99.

dnl Copyright (C) 2002-2004 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.

# Prepare for substituting <stdbool.h> if it is not supported.

AC_DEFUN([AM_STDBOOL_H],
[
  AC_REQUIRE([AC_HEADER_STDBOOL])

  # Define two additional variables used in the Makefile substitution.

  if test "$ac_cv_header_stdbool_h" = yes; then
    STDBOOL_H=''
  else
    STDBOOL_H='stdbool.h'
  fi
  AC_SUBST([STDBOOL_H])

  if test "$ac_cv_type__Bool" = yes; then
    HAVE__BOOL=1
  else
    HAVE__BOOL=0
  fi
  AC_SUBST([HAVE__BOOL])
])

# This macro is only needed in autoconf <= 2.59.  Newer versions of autoconf
# have this macro built-in.

AC_DEFUN([AC_HEADER_STDBOOL],
  [AC_CACHE_CHECK([for stdbool.h that conforms to C99],
     [ac_cv_header_stdbool_h],
     [AC_TRY_COMPILE(
	[
	  #include <stdbool.h>
	  #ifndef bool
	   "error: bool is not defined"
	  #endif
	  #ifndef false
	   "error: false is not defined"
	  #endif
	  #if false
	   "error: false is not 0"
	  #endif
	  #ifndef true
	   "error: true is not defined"
	  #endif
	  #if true != 1
	   "error: true is not 1"
	  #endif
	  #ifndef __bool_true_false_are_defined
	   "error: __bool_true_false_are_defined is not defined"
	  #endif

	  struct s { _Bool s: 1; _Bool t; } s;

	  char a[true == 1 ? 1 : -1];
	  char b[false == 0 ? 1 : -1];
	  char c[__bool_true_false_are_defined == 1 ? 1 : -1];
	  char d[(bool) -0.5 == true ? 1 : -1];
	  bool e = &s;
	  char f[(_Bool) -0.0 == false ? 1 : -1];
	  char g[true];
	  char h[sizeof (_Bool)];
	  char i[sizeof s.t];
	  enum { j = false, k = true, l = false * true, m = true * 256 };
	  _Bool n[m];
	  char o[sizeof n == m * sizeof n[0] ? 1 : -1];
	],
	[
	  return (!a + !b + !c + !d + !e + !f + !g + !h + !i + !j + !k + !l
		  + !m + !n + !o);
	],
	[ac_cv_header_stdbool_h=yes],
	[ac_cv_header_stdbool_h=no])])
   AC_CHECK_TYPES([_Bool])
   if test $ac_cv_header_stdbool_h = yes; then
     AC_DEFINE(HAVE_STDBOOL_H, 1, [Define to 1 if stdbool.h conforms to C99.])
   fi])