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+# Check for stdbool.h that conforms to C99.
+
+dnl Copyright (C) 2002-2006, 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.
+
+#serial 8
+
+# Prepare for substituting <stdbool.h> if it is not supported.
+
+AC_DEFUN([AM_STDBOOL_H],
+[
+ AC_REQUIRE([AC_CHECK_HEADER_STDBOOL])
+ AC_REQUIRE([AC_CANONICAL_HOST])
+
+ dnl On some platforms, <stdbool.h> does not exist or does not conform to C99.
+ dnl On Solaris 10 with CC=cc CXX=CC, <stdbool.h> exists but is not usable
+ dnl in C++ mode (and no <cstdbool> exists). In this case, we use our
+ dnl replacement, also in C mode (for binary compatibility between C and C++).
+ if test "$ac_cv_header_stdbool_h" = yes; then
+ case "$host_os" in
+ solaris*)
+ if test -z "$GCC"; then
+ STDBOOL_H='stdbool.h'
+ else
+ STDBOOL_H=''
+ fi
+ ;;
+ *)
+ STDBOOL_H=''
+ ;;
+ esac
+ else
+ STDBOOL_H='stdbool.h'
+ fi
+ AC_SUBST([STDBOOL_H])
+ AM_CONDITIONAL([GL_GENERATE_STDBOOL_H], [test -n "$STDBOOL_H"])
+
+ if test "$ac_cv_type__Bool" = yes; then
+ HAVE__BOOL=1
+ else
+ HAVE__BOOL=0
+ fi
+ AC_SUBST([HAVE__BOOL])
+])
+
+# AM_STDBOOL_H will be renamed to gl_STDBOOL_H in the future.
+AC_DEFUN([gl_STDBOOL_H], [AM_STDBOOL_H])
+
+# This version of the macro is needed in autoconf <= 2.68.
+
+AC_DEFUN([AC_CHECK_HEADER_STDBOOL],
+ [AC_CACHE_CHECK([for stdbool.h that conforms to C99],
+ [ac_cv_header_stdbool_h],
+ [AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[
+ #include <stdbool.h>
+
+ #ifdef __cplusplus
+ typedef bool Bool;
+ #else
+ typedef _Bool Bool;
+ #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
+ #endif
+
+ #ifndef __bool_true_false_are_defined
+ "error: __bool_true_false_are_defined is not defined"
+ #endif
+
+ struct s { Bool s: 1; Bool t; bool u: 1; bool v; } 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];
+ /* See body of main program for 'e'. */
+ 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 };
+ /* The following fails for
+ HP aC++/ANSI C B3910B A.05.55 [Dec 04 2003]. */
+ Bool n[m];
+ char o[sizeof n == m * sizeof n[0] ? 1 : -1];
+ char p[-1 - (Bool) 0 < 0 && -1 - (bool) 0 < 0 ? 1 : -1];
+ /* Catch a bug in an HP-UX C compiler. See
+ https://gcc.gnu.org/ml/gcc-patches/2003-12/msg02303.html
+ https://lists.gnu.org/r/bug-coreutils/2005-11/msg00161.html
+ */
+ Bool q = true;
+ Bool *pq = &q;
+ bool *qq = &q;
+ ]],
+ [[
+ bool e = &s;
+ *pq |= q; *pq |= ! q;
+ *qq |= q; *qq |= ! q;
+ /* Refer to every declared value, to avoid compiler optimizations. */
+ return (!a + !b + !c + !d + !e + !f + !g + !h + !i + !!j + !k + !!l
+ + !m + !n + !o + !p + !q + !pq + !qq);
+ ]])],
+ [ac_cv_header_stdbool_h=yes],
+ [ac_cv_header_stdbool_h=no])])
+ AC_CHECK_TYPES([_Bool])
+])