| 1 | /* C++ compatible function declaration macros.
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| 2 | Copyright (C) 2010-2021 Free Software Foundation, Inc.
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| 3 |
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| 4 | This program is free software: you can redistribute it and/or modify it
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| 5 | under the terms of the GNU Lesser General Public License as published
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| 6 | by the Free Software Foundation; either version 2 of the License, or
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| 7 | (at your option) any later version.
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| 8 |
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| 9 | This program is distributed in the hope that it will be useful,
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 12 | Lesser General Public License for more details.
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| 13 |
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| 14 | You should have received a copy of the GNU Lesser General Public License
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| 15 | along with this program. If not, see <https://www.gnu.org/licenses/>. */
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| 16 |
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| 17 | #ifndef _GL_CXXDEFS_H
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| 18 | #define _GL_CXXDEFS_H
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| 19 |
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| 20 | /* Begin/end the GNULIB_NAMESPACE namespace. */
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| 21 | #if defined __cplusplus && defined GNULIB_NAMESPACE
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| 22 | # define _GL_BEGIN_NAMESPACE namespace GNULIB_NAMESPACE {
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| 23 | # define _GL_END_NAMESPACE }
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| 24 | #else
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| 25 | # define _GL_BEGIN_NAMESPACE
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| 26 | # define _GL_END_NAMESPACE
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| 27 | #endif
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| 28 |
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| 29 | /* The three most frequent use cases of these macros are:
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| 30 |
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| 31 | * For providing a substitute for a function that is missing on some
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| 32 | platforms, but is declared and works fine on the platforms on which
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| 33 | it exists:
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| 34 |
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| 35 | #if @GNULIB_FOO@
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| 36 | # if !@HAVE_FOO@
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| 37 | _GL_FUNCDECL_SYS (foo, ...);
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| 38 | # endif
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| 39 | _GL_CXXALIAS_SYS (foo, ...);
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| 40 | _GL_CXXALIASWARN (foo);
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| 41 | #elif defined GNULIB_POSIXCHECK
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| 42 | ...
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| 43 | #endif
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| 44 |
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| 45 | * For providing a replacement for a function that exists on all platforms,
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| 46 | but is broken/insufficient and needs to be replaced on some platforms:
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| 47 |
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| 48 | #if @GNULIB_FOO@
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| 49 | # if @REPLACE_FOO@
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| 50 | # if !(defined __cplusplus && defined GNULIB_NAMESPACE)
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| 51 | # undef foo
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| 52 | # define foo rpl_foo
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| 53 | # endif
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| 54 | _GL_FUNCDECL_RPL (foo, ...);
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| 55 | _GL_CXXALIAS_RPL (foo, ...);
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| 56 | # else
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| 57 | _GL_CXXALIAS_SYS (foo, ...);
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| 58 | # endif
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| 59 | _GL_CXXALIASWARN (foo);
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| 60 | #elif defined GNULIB_POSIXCHECK
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| 61 | ...
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| 62 | #endif
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| 63 |
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| 64 | * For providing a replacement for a function that exists on some platforms
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| 65 | but is broken/insufficient and needs to be replaced on some of them and
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| 66 | is additionally either missing or undeclared on some other platforms:
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| 67 |
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| 68 | #if @GNULIB_FOO@
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| 69 | # if @REPLACE_FOO@
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| 70 | # if !(defined __cplusplus && defined GNULIB_NAMESPACE)
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| 71 | # undef foo
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| 72 | # define foo rpl_foo
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| 73 | # endif
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| 74 | _GL_FUNCDECL_RPL (foo, ...);
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| 75 | _GL_CXXALIAS_RPL (foo, ...);
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| 76 | # else
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| 77 | # if !@HAVE_FOO@ or if !@HAVE_DECL_FOO@
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| 78 | _GL_FUNCDECL_SYS (foo, ...);
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| 79 | # endif
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| 80 | _GL_CXXALIAS_SYS (foo, ...);
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| 81 | # endif
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| 82 | _GL_CXXALIASWARN (foo);
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| 83 | #elif defined GNULIB_POSIXCHECK
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| 84 | ...
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| 85 | #endif
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| 86 | */
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| 87 |
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| 88 | /* _GL_EXTERN_C declaration;
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| 89 | performs the declaration with C linkage. */
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| 90 | #if defined __cplusplus
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| 91 | # define _GL_EXTERN_C extern "C"
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| 92 | #else
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| 93 | # define _GL_EXTERN_C extern
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| 94 | #endif
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| 95 |
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| 96 | /* _GL_FUNCDECL_RPL (func, rettype, parameters_and_attributes);
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| 97 | declares a replacement function, named rpl_func, with the given prototype,
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| 98 | consisting of return type, parameters, and attributes.
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| 99 | Example:
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| 100 | _GL_FUNCDECL_RPL (open, int, (const char *filename, int flags, ...)
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| 101 | _GL_ARG_NONNULL ((1)));
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| 102 | */
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| 103 | #define _GL_FUNCDECL_RPL(func,rettype,parameters_and_attributes) \
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| 104 | _GL_FUNCDECL_RPL_1 (rpl_##func, rettype, parameters_and_attributes)
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| 105 | #define _GL_FUNCDECL_RPL_1(rpl_func,rettype,parameters_and_attributes) \
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| 106 | _GL_EXTERN_C rettype rpl_func parameters_and_attributes
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| 107 |
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| 108 | /* _GL_FUNCDECL_SYS (func, rettype, parameters_and_attributes);
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| 109 | declares the system function, named func, with the given prototype,
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| 110 | consisting of return type, parameters, and attributes.
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| 111 | Example:
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| 112 | _GL_FUNCDECL_SYS (open, int, (const char *filename, int flags, ...)
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| 113 | _GL_ARG_NONNULL ((1)));
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| 114 | */
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| 115 | #define _GL_FUNCDECL_SYS(func,rettype,parameters_and_attributes) \
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| 116 | _GL_EXTERN_C rettype func parameters_and_attributes
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| 117 |
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| 118 | /* _GL_CXXALIAS_RPL (func, rettype, parameters);
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| 119 | declares a C++ alias called GNULIB_NAMESPACE::func
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| 120 | that redirects to rpl_func, if GNULIB_NAMESPACE is defined.
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| 121 | Example:
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| 122 | _GL_CXXALIAS_RPL (open, int, (const char *filename, int flags, ...));
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| 123 |
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| 124 | Wrapping rpl_func in an object with an inline conversion operator
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| 125 | avoids a reference to rpl_func unless GNULIB_NAMESPACE::func is
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| 126 | actually used in the program. */
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| 127 | #define _GL_CXXALIAS_RPL(func,rettype,parameters) \
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| 128 | _GL_CXXALIAS_RPL_1 (func, rpl_##func, rettype, parameters)
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| 129 | #if defined __cplusplus && defined GNULIB_NAMESPACE
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| 130 | # define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \
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| 131 | namespace GNULIB_NAMESPACE \
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| 132 | { \
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| 133 | static const struct _gl_ ## func ## _wrapper \
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| 134 | { \
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| 135 | typedef rettype (*type) parameters; \
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| 136 | \
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| 137 | inline operator type () const \
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| 138 | { \
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| 139 | return ::rpl_func; \
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| 140 | } \
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| 141 | } func = {}; \
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| 142 | } \
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| 143 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 144 | #else
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| 145 | # define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \
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| 146 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 147 | #endif
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| 148 |
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| 149 | /* _GL_CXXALIAS_MDA (func, rettype, parameters);
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| 150 | is to be used when func is a Microsoft deprecated alias, on native Windows.
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| 151 | It declares a C++ alias called GNULIB_NAMESPACE::func
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| 152 | that redirects to _func, if GNULIB_NAMESPACE is defined.
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| 153 | Example:
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| 154 | _GL_CXXALIAS_MDA (open, int, (const char *filename, int flags, ...));
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| 155 | */
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| 156 | #define _GL_CXXALIAS_MDA(func,rettype,parameters) \
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| 157 | _GL_CXXALIAS_RPL_1 (func, _##func, rettype, parameters)
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| 158 |
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| 159 | /* _GL_CXXALIAS_RPL_CAST_1 (func, rpl_func, rettype, parameters);
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| 160 | is like _GL_CXXALIAS_RPL_1 (func, rpl_func, rettype, parameters);
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| 161 | except that the C function rpl_func may have a slightly different
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| 162 | declaration. A cast is used to silence the "invalid conversion" error
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| 163 | that would otherwise occur. */
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| 164 | #if defined __cplusplus && defined GNULIB_NAMESPACE
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| 165 | # define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \
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| 166 | namespace GNULIB_NAMESPACE \
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| 167 | { \
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| 168 | static const struct _gl_ ## func ## _wrapper \
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| 169 | { \
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| 170 | typedef rettype (*type) parameters; \
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| 171 | \
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| 172 | inline operator type () const \
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| 173 | { \
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| 174 | return reinterpret_cast<type>(::rpl_func); \
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| 175 | } \
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| 176 | } func = {}; \
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| 177 | } \
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| 178 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 179 | #else
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| 180 | # define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \
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| 181 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 182 | #endif
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| 183 |
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| 184 | /* _GL_CXXALIAS_MDA_CAST (func, rettype, parameters);
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| 185 | is like _GL_CXXALIAS_MDA (func, rettype, parameters);
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| 186 | except that the C function func may have a slightly different declaration.
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| 187 | A cast is used to silence the "invalid conversion" error that would
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| 188 | otherwise occur. */
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| 189 | #define _GL_CXXALIAS_MDA_CAST(func,rettype,parameters) \
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| 190 | _GL_CXXALIAS_RPL_CAST_1 (func, _##func, rettype, parameters)
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| 191 |
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| 192 | /* _GL_CXXALIAS_SYS (func, rettype, parameters);
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| 193 | declares a C++ alias called GNULIB_NAMESPACE::func
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| 194 | that redirects to the system provided function func, if GNULIB_NAMESPACE
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| 195 | is defined.
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| 196 | Example:
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| 197 | _GL_CXXALIAS_SYS (open, int, (const char *filename, int flags, ...));
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| 198 |
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| 199 | Wrapping func in an object with an inline conversion operator
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| 200 | avoids a reference to func unless GNULIB_NAMESPACE::func is
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| 201 | actually used in the program. */
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| 202 | #if defined __cplusplus && defined GNULIB_NAMESPACE
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| 203 | # define _GL_CXXALIAS_SYS(func,rettype,parameters) \
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| 204 | namespace GNULIB_NAMESPACE \
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| 205 | { \
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| 206 | static const struct _gl_ ## func ## _wrapper \
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| 207 | { \
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| 208 | typedef rettype (*type) parameters; \
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| 209 | \
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| 210 | inline operator type () const \
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| 211 | { \
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| 212 | return ::func; \
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| 213 | } \
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| 214 | } func = {}; \
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| 215 | } \
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| 216 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 217 | #else
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| 218 | # define _GL_CXXALIAS_SYS(func,rettype,parameters) \
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| 219 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 220 | #endif
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| 221 |
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| 222 | /* _GL_CXXALIAS_SYS_CAST (func, rettype, parameters);
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| 223 | is like _GL_CXXALIAS_SYS (func, rettype, parameters);
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| 224 | except that the C function func may have a slightly different declaration.
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| 225 | A cast is used to silence the "invalid conversion" error that would
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| 226 | otherwise occur. */
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| 227 | #if defined __cplusplus && defined GNULIB_NAMESPACE
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| 228 | # define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \
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| 229 | namespace GNULIB_NAMESPACE \
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| 230 | { \
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| 231 | static const struct _gl_ ## func ## _wrapper \
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| 232 | { \
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| 233 | typedef rettype (*type) parameters; \
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| 234 | \
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| 235 | inline operator type () const \
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| 236 | { \
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| 237 | return reinterpret_cast<type>(::func); \
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| 238 | } \
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| 239 | } func = {}; \
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| 240 | } \
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| 241 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 242 | #else
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| 243 | # define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \
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| 244 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 245 | #endif
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| 246 |
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| 247 | /* _GL_CXXALIAS_SYS_CAST2 (func, rettype, parameters, rettype2, parameters2);
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| 248 | is like _GL_CXXALIAS_SYS (func, rettype, parameters);
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| 249 | except that the C function is picked among a set of overloaded functions,
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| 250 | namely the one with rettype2 and parameters2. Two consecutive casts
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| 251 | are used to silence the "cannot find a match" and "invalid conversion"
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| 252 | errors that would otherwise occur. */
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| 253 | #if defined __cplusplus && defined GNULIB_NAMESPACE
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| 254 | /* The outer cast must be a reinterpret_cast.
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| 255 | The inner cast: When the function is defined as a set of overloaded
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| 256 | functions, it works as a static_cast<>, choosing the designated variant.
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| 257 | When the function is defined as a single variant, it works as a
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| 258 | reinterpret_cast<>. The parenthesized cast syntax works both ways. */
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| 259 | # define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \
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| 260 | namespace GNULIB_NAMESPACE \
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| 261 | { \
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| 262 | static const struct _gl_ ## func ## _wrapper \
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| 263 | { \
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| 264 | typedef rettype (*type) parameters; \
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| 265 | \
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| 266 | inline operator type () const \
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| 267 | { \
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| 268 | return reinterpret_cast<type>((rettype2 (*) parameters2)(::func)); \
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| 269 | } \
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| 270 | } func = {}; \
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| 271 | } \
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| 272 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 273 | #else
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| 274 | # define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \
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| 275 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 276 | #endif
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| 277 |
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| 278 | /* _GL_CXXALIASWARN (func);
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| 279 | causes a warning to be emitted when ::func is used but not when
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| 280 | GNULIB_NAMESPACE::func is used. func must be defined without overloaded
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| 281 | variants. */
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| 282 | #if defined __cplusplus && defined GNULIB_NAMESPACE
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| 283 | # define _GL_CXXALIASWARN(func) \
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| 284 | _GL_CXXALIASWARN_1 (func, GNULIB_NAMESPACE)
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| 285 | # define _GL_CXXALIASWARN_1(func,namespace) \
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| 286 | _GL_CXXALIASWARN_2 (func, namespace)
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| 287 | /* To work around GCC bug <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
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| 288 | we enable the warning only when not optimizing. */
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| 289 | # if !(defined __GNUC__ && !defined __clang__ && __OPTIMIZE__)
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| 290 | # define _GL_CXXALIASWARN_2(func,namespace) \
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| 291 | _GL_WARN_ON_USE (func, \
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| 292 | "The symbol ::" #func " refers to the system function. " \
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| 293 | "Use " #namespace "::" #func " instead.")
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| 294 | # elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
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| 295 | # define _GL_CXXALIASWARN_2(func,namespace) \
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| 296 | extern __typeof__ (func) func
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| 297 | # else
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| 298 | # define _GL_CXXALIASWARN_2(func,namespace) \
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| 299 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 300 | # endif
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| 301 | #else
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| 302 | # define _GL_CXXALIASWARN(func) \
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| 303 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 304 | #endif
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| 305 |
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| 306 | /* _GL_CXXALIASWARN1 (func, rettype, parameters_and_attributes);
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| 307 | causes a warning to be emitted when the given overloaded variant of ::func
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| 308 | is used but not when GNULIB_NAMESPACE::func is used. */
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| 309 | #if defined __cplusplus && defined GNULIB_NAMESPACE
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| 310 | # define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \
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| 311 | _GL_CXXALIASWARN1_1 (func, rettype, parameters_and_attributes, \
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| 312 | GNULIB_NAMESPACE)
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| 313 | # define _GL_CXXALIASWARN1_1(func,rettype,parameters_and_attributes,namespace) \
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| 314 | _GL_CXXALIASWARN1_2 (func, rettype, parameters_and_attributes, namespace)
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| 315 | /* To work around GCC bug <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
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| 316 | we enable the warning only when not optimizing. */
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| 317 | # if !(defined __GNUC__ && !defined __clang__ && __OPTIMIZE__)
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| 318 | # define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
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| 319 | _GL_WARN_ON_USE_CXX (func, rettype, rettype, parameters_and_attributes, \
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| 320 | "The symbol ::" #func " refers to the system function. " \
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| 321 | "Use " #namespace "::" #func " instead.")
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| 322 | # else
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| 323 | # define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
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| 324 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 325 | # endif
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| 326 | #else
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| 327 | # define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \
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| 328 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 329 | #endif
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| 330 |
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| 331 | #endif /* _GL_CXXDEFS_H */
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