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54 lines
1.8 KiB
Plaintext
54 lines
1.8 KiB
Plaintext
# c-bool.m4
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# serial 1
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dnl Copyright 2022-2024 Free Software Foundation, Inc.
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dnl This file is free software; the Free Software Foundation
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dnl gives unlimited permission to copy and/or distribute it,
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dnl with or without modifications, as long as this notice is preserved.
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# Check for bool that conforms to C2023.
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AC_DEFUN([gl_C_BOOL],
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[
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AC_CACHE_CHECK([for bool, true, false], [gl_cv_c_bool],
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[AC_COMPILE_IFELSE(
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[AC_LANG_SOURCE([[
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#if true == false
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#error "true == false"
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#endif
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extern bool b;
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bool b = true == false;]])],
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[gl_cv_c_bool=yes],
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[gl_cv_c_bool=no])])
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if test "$gl_cv_c_bool" = yes; then
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AC_DEFINE([HAVE_C_BOOL], [1],
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[Define to 1 if bool, true and false work as per C2023.])
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fi
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AC_CHECK_HEADERS_ONCE([stdbool.h])
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dnl The "zz" puts this toward config.h's end, to avoid potential
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dnl collisions with other definitions.
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dnl If 'bool', 'true' and 'false' do not work, arrange for them to work.
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dnl In C, this means including <stdbool.h> if it is not already included.
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dnl However, if the preprocessor mistakenly treats 'true' as 0,
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dnl define it to a bool expression equal to 1; this is needed in
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dnl Sun C++ 5.11 (Oracle Solaris Studio 12.2, 2010) and older.
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AH_VERBATIM([zzbool],
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[#ifndef HAVE_C_BOOL
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# if !defined __cplusplus && !defined __bool_true_false_are_defined
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# if HAVE_STDBOOL_H
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# include <stdbool.h>
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# else
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# if defined __SUNPRO_C
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# error "<stdbool.h> is not usable with this configuration. To make it usable, add -D_STDC_C99= to $CC."
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# else
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# error "<stdbool.h> does not exist on this platform. Use gnulib module 'stdbool-c99' instead of gnulib module 'stdbool'."
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# endif
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# endif
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# endif
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# if !true
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# define true (!false)
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# endif
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#endif])
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])
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