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Annotation of embedaddon/libiconv/srcm4/stdbool.m4, revision 1.1.1.1

1.1       misho       1: # Check for stdbool.h that conforms to C99.
                      2: 
                      3: dnl Copyright (C) 2002-2006, 2009 Free Software Foundation, Inc.
                      4: dnl This file is free software; the Free Software Foundation
                      5: dnl gives unlimited permission to copy and/or distribute it,
                      6: dnl with or without modifications, as long as this notice is preserved.
                      7: 
                      8: # Prepare for substituting <stdbool.h> if it is not supported.
                      9: 
                     10: AC_DEFUN([AM_STDBOOL_H],
                     11: [
                     12:   AC_REQUIRE([AC_HEADER_STDBOOL])
                     13: 
                     14:   # Define two additional variables used in the Makefile substitution.
                     15: 
                     16:   if test "$ac_cv_header_stdbool_h" = yes; then
                     17:     STDBOOL_H=''
                     18:   else
                     19:     STDBOOL_H='stdbool.h'
                     20:   fi
                     21:   AC_SUBST([STDBOOL_H])
                     22: 
                     23:   if test "$ac_cv_type__Bool" = yes; then
                     24:     HAVE__BOOL=1
                     25:   else
                     26:     HAVE__BOOL=0
                     27:   fi
                     28:   AC_SUBST([HAVE__BOOL])
                     29: ])
                     30: 
                     31: # AM_STDBOOL_H will be renamed to gl_STDBOOL_H in the future.
                     32: AC_DEFUN([gl_STDBOOL_H], [AM_STDBOOL_H])
                     33: 
                     34: # This macro is only needed in autoconf <= 2.59.  Newer versions of autoconf
                     35: # have this macro built-in.
                     36: 
                     37: AC_DEFUN([AC_HEADER_STDBOOL],
                     38:   [AC_CACHE_CHECK([for stdbool.h that conforms to C99],
                     39:      [ac_cv_header_stdbool_h],
                     40:      [AC_TRY_COMPILE(
                     41:        [
                     42:          #include <stdbool.h>
                     43:          #ifndef bool
                     44:           "error: bool is not defined"
                     45:          #endif
                     46:          #ifndef false
                     47:           "error: false is not defined"
                     48:          #endif
                     49:          #if false
                     50:           "error: false is not 0"
                     51:          #endif
                     52:          #ifndef true
                     53:           "error: true is not defined"
                     54:          #endif
                     55:          #if true != 1
                     56:           "error: true is not 1"
                     57:          #endif
                     58:          #ifndef __bool_true_false_are_defined
                     59:           "error: __bool_true_false_are_defined is not defined"
                     60:          #endif
                     61: 
                     62:          struct s { _Bool s: 1; _Bool t; } s;
                     63: 
                     64:          char a[true == 1 ? 1 : -1];
                     65:          char b[false == 0 ? 1 : -1];
                     66:          char c[__bool_true_false_are_defined == 1 ? 1 : -1];
                     67:          char d[(bool) 0.5 == true ? 1 : -1];
                     68:          bool e = &s;
                     69:          char f[(_Bool) 0.0 == false ? 1 : -1];
                     70:          char g[true];
                     71:          char h[sizeof (_Bool)];
                     72:          char i[sizeof s.t];
                     73:          enum { j = false, k = true, l = false * true, m = true * 256 };
                     74:          _Bool n[m];
                     75:          char o[sizeof n == m * sizeof n[0] ? 1 : -1];
                     76:          char p[-1 - (_Bool) 0 < 0 && -1 - (bool) 0 < 0 ? 1 : -1];
                     77:          #if defined __xlc__ || defined __GNUC__
                     78:           /* Catch a bug in IBM AIX xlc compiler version 6.0.0.0
                     79:              reported by James Lemley on 2005-10-05; see
                     80:              http://lists.gnu.org/archive/html/bug-coreutils/2005-10/msg00086.html
                     81:              This test is not quite right, since xlc is allowed to
                     82:              reject this program, as the initializer for xlcbug is
                     83:              not one of the forms that C requires support for.
                     84:              However, doing the test right would require a run-time
                     85:              test, and that would make cross-compilation harder.
                     86:              Let us hope that IBM fixes the xlc bug, and also adds
                     87:              support for this kind of constant expression.  In the
                     88:              meantime, this test will reject xlc, which is OK, since
                     89:              our stdbool.h substitute should suffice.  We also test
                     90:              this with GCC, where it should work, to detect more
                     91:              quickly whether someone messes up the test in the
                     92:              future.  */
                     93:           char digs[] = "0123456789";
                     94:           int xlcbug = 1 / (&(digs + 5)[-2 + (bool) 1] == &digs[4] ? 1 : -1);
                     95:          #endif
                     96:          /* Catch a bug in an HP-UX C compiler.  See
                     97:             http://gcc.gnu.org/ml/gcc-patches/2003-12/msg02303.html
                     98:             http://lists.gnu.org/archive/html/bug-coreutils/2005-11/msg00161.html
                     99:           */
                    100:          _Bool q = true;
                    101:          _Bool *pq = &q;
                    102:        ],
                    103:        [
                    104:          *pq |= q;
                    105:          *pq |= ! q;
                    106:          /* Refer to every declared value, to avoid compiler optimizations.  */
                    107:          return (!a + !b + !c + !d + !e + !f + !g + !h + !i + !!j + !k + !!l
                    108:                  + !m + !n + !o + !p + !q + !pq);
                    109:        ],
                    110:        [ac_cv_header_stdbool_h=yes],
                    111:        [ac_cv_header_stdbool_h=no])])
                    112:    AC_CHECK_TYPES([_Bool])
                    113:    if test $ac_cv_header_stdbool_h = yes; then
                    114:      AC_DEFINE([HAVE_STDBOOL_H], [1], [Define to 1 if stdbool.h conforms to C99.])
                    115:    fi])