| 1 | /* C++ compatible function declaration macros.
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| 2 | Copyright (C) 2010-2012 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 General Public License as published
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| 6 | by the Free Software Foundation; either version 3 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 | 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 General Public License
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| 15 | along with this program. If not, see <http://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 | /* The three most frequent use cases of these macros are:
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| 21 |
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| 22 | * For providing a substitute for a function that is missing on some
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| 23 | platforms, but is declared and works fine on the platforms on which
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| 24 | it exists:
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| 25 |
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| 26 | #if @GNULIB_FOO@
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| 27 | # if !@HAVE_FOO@
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| 28 | _GL_FUNCDECL_SYS (foo, ...);
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| 29 | # endif
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| 30 | _GL_CXXALIAS_SYS (foo, ...);
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| 31 | _GL_CXXALIASWARN (foo);
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| 32 | #elif defined GNULIB_POSIXCHECK
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| 33 | ...
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| 34 | #endif
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| 35 |
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| 36 | * For providing a replacement for a function that exists on all platforms,
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| 37 | but is broken/insufficient and needs to be replaced on some platforms:
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| 38 |
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| 39 | #if @GNULIB_FOO@
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| 40 | # if @REPLACE_FOO@
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| 41 | # if !(defined __cplusplus && defined GNULIB_NAMESPACE)
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| 42 | # undef foo
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| 43 | # define foo rpl_foo
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| 44 | # endif
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| 45 | _GL_FUNCDECL_RPL (foo, ...);
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| 46 | _GL_CXXALIAS_RPL (foo, ...);
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| 47 | # else
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| 48 | _GL_CXXALIAS_SYS (foo, ...);
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| 49 | # endif
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| 50 | _GL_CXXALIASWARN (foo);
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| 51 | #elif defined GNULIB_POSIXCHECK
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| 52 | ...
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| 53 | #endif
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| 54 |
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| 55 | * For providing a replacement for a function that exists on some platforms
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| 56 | but is broken/insufficient and needs to be replaced on some of them and
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| 57 | is additionally either missing or undeclared on some other platforms:
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| 58 |
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| 59 | #if @GNULIB_FOO@
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| 60 | # if @REPLACE_FOO@
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| 61 | # if !(defined __cplusplus && defined GNULIB_NAMESPACE)
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| 62 | # undef foo
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| 63 | # define foo rpl_foo
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| 64 | # endif
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| 65 | _GL_FUNCDECL_RPL (foo, ...);
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| 66 | _GL_CXXALIAS_RPL (foo, ...);
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| 67 | # else
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| 68 | # if !@HAVE_FOO@ or if !@HAVE_DECL_FOO@
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| 69 | _GL_FUNCDECL_SYS (foo, ...);
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| 70 | # endif
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| 71 | _GL_CXXALIAS_SYS (foo, ...);
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| 72 | # endif
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| 73 | _GL_CXXALIASWARN (foo);
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| 74 | #elif defined GNULIB_POSIXCHECK
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| 75 | ...
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| 76 | #endif
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| 77 | */
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| 78 |
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| 79 | /* _GL_EXTERN_C declaration;
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| 80 | performs the declaration with C linkage. */
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| 81 | #if defined __cplusplus
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| 82 | # define _GL_EXTERN_C extern "C"
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| 83 | #else
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| 84 | # define _GL_EXTERN_C extern
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| 85 | #endif
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| 86 |
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| 87 | /* _GL_FUNCDECL_RPL (func, rettype, parameters_and_attributes);
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| 88 | declares a replacement function, named rpl_func, with the given prototype,
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| 89 | consisting of return type, parameters, and attributes.
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| 90 | Example:
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| 91 | _GL_FUNCDECL_RPL (open, int, (const char *filename, int flags, ...)
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| 92 | _GL_ARG_NONNULL ((1)));
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| 93 | */
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| 94 | #define _GL_FUNCDECL_RPL(func,rettype,parameters_and_attributes) \
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| 95 | _GL_FUNCDECL_RPL_1 (rpl_##func, rettype, parameters_and_attributes)
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| 96 | #define _GL_FUNCDECL_RPL_1(rpl_func,rettype,parameters_and_attributes) \
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| 97 | _GL_EXTERN_C rettype rpl_func parameters_and_attributes
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| 98 |
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| 99 | /* _GL_FUNCDECL_SYS (func, rettype, parameters_and_attributes);
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| 100 | declares the system function, named func, with the given prototype,
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| 101 | consisting of return type, parameters, and attributes.
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| 102 | Example:
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| 103 | _GL_FUNCDECL_SYS (open, int, (const char *filename, int flags, ...)
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| 104 | _GL_ARG_NONNULL ((1)));
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| 105 | */
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| 106 | #define _GL_FUNCDECL_SYS(func,rettype,parameters_and_attributes) \
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| 107 | _GL_EXTERN_C rettype func parameters_and_attributes
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| 108 |
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| 109 | /* _GL_CXXALIAS_RPL (func, rettype, parameters);
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| 110 | declares a C++ alias called GNULIB_NAMESPACE::func
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| 111 | that redirects to rpl_func, if GNULIB_NAMESPACE is defined.
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| 112 | Example:
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| 113 | _GL_CXXALIAS_RPL (open, int, (const char *filename, int flags, ...));
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| 114 | */
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| 115 | #define _GL_CXXALIAS_RPL(func,rettype,parameters) \
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| 116 | _GL_CXXALIAS_RPL_1 (func, rpl_##func, rettype, parameters)
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| 117 | #if defined __cplusplus && defined GNULIB_NAMESPACE
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| 118 | # define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \
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| 119 | namespace GNULIB_NAMESPACE \
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| 120 | { \
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| 121 | rettype (*const func) parameters = ::rpl_func; \
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| 122 | } \
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| 123 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 124 | #else
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| 125 | # define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \
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| 126 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 127 | #endif
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| 128 |
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| 129 | /* _GL_CXXALIAS_RPL_CAST_1 (func, rpl_func, rettype, parameters);
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| 130 | is like _GL_CXXALIAS_RPL_1 (func, rpl_func, rettype, parameters);
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| 131 | except that the C function rpl_func may have a slightly different
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| 132 | declaration. A cast is used to silence the "invalid conversion" error
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| 133 | that would otherwise occur. */
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| 134 | #if defined __cplusplus && defined GNULIB_NAMESPACE
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| 135 | # define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \
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| 136 | namespace GNULIB_NAMESPACE \
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| 137 | { \
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| 138 | rettype (*const func) parameters = \
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| 139 | reinterpret_cast<rettype(*)parameters>(::rpl_func); \
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| 140 | } \
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| 141 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 142 | #else
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| 143 | # define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \
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| 144 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 145 | #endif
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| 146 |
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| 147 | /* _GL_CXXALIAS_SYS (func, rettype, parameters);
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| 148 | declares a C++ alias called GNULIB_NAMESPACE::func
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| 149 | that redirects to the system provided function func, if GNULIB_NAMESPACE
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| 150 | is defined.
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| 151 | Example:
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| 152 | _GL_CXXALIAS_SYS (open, int, (const char *filename, int flags, ...));
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| 153 | */
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| 154 | #if defined __cplusplus && defined GNULIB_NAMESPACE
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| 155 | /* If we were to write
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| 156 | rettype (*const func) parameters = ::func;
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| 157 | like above in _GL_CXXALIAS_RPL_1, the compiler could optimize calls
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| 158 | better (remove an indirection through a 'static' pointer variable),
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| 159 | but then the _GL_CXXALIASWARN macro below would cause a warning not only
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| 160 | for uses of ::func but also for uses of GNULIB_NAMESPACE::func. */
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| 161 | # define _GL_CXXALIAS_SYS(func,rettype,parameters) \
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| 162 | namespace GNULIB_NAMESPACE \
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| 163 | { \
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| 164 | static rettype (*func) parameters = ::func; \
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| 165 | } \
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| 166 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 167 | #else
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| 168 | # define _GL_CXXALIAS_SYS(func,rettype,parameters) \
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| 169 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 170 | #endif
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| 171 |
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| 172 | /* _GL_CXXALIAS_SYS_CAST (func, rettype, parameters);
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| 173 | is like _GL_CXXALIAS_SYS (func, rettype, parameters);
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| 174 | except that the C function func may have a slightly different declaration.
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| 175 | A cast is used to silence the "invalid conversion" error that would
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| 176 | otherwise occur. */
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| 177 | #if defined __cplusplus && defined GNULIB_NAMESPACE
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| 178 | # define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \
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| 179 | namespace GNULIB_NAMESPACE \
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| 180 | { \
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| 181 | static rettype (*func) parameters = \
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| 182 | reinterpret_cast<rettype(*)parameters>(::func); \
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| 183 | } \
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| 184 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 185 | #else
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| 186 | # define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \
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| 187 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 188 | #endif
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| 189 |
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| 190 | /* _GL_CXXALIAS_SYS_CAST2 (func, rettype, parameters, rettype2, parameters2);
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| 191 | is like _GL_CXXALIAS_SYS (func, rettype, parameters);
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| 192 | except that the C function is picked among a set of overloaded functions,
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| 193 | namely the one with rettype2 and parameters2. Two consecutive casts
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| 194 | are used to silence the "cannot find a match" and "invalid conversion"
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| 195 | errors that would otherwise occur. */
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| 196 | #if defined __cplusplus && defined GNULIB_NAMESPACE
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| 197 | /* The outer cast must be a reinterpret_cast.
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| 198 | The inner cast: When the function is defined as a set of overloaded
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| 199 | functions, it works as a static_cast<>, choosing the designated variant.
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| 200 | When the function is defined as a single variant, it works as a
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| 201 | reinterpret_cast<>. The parenthesized cast syntax works both ways. */
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| 202 | # define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \
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| 203 | namespace GNULIB_NAMESPACE \
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| 204 | { \
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| 205 | static rettype (*func) parameters = \
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| 206 | reinterpret_cast<rettype(*)parameters>( \
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| 207 | (rettype2(*)parameters2)(::func)); \
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| 208 | } \
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| 209 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 210 | #else
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| 211 | # define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \
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| 212 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 213 | #endif
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| 214 |
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| 215 | /* _GL_CXXALIASWARN (func);
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| 216 | causes a warning to be emitted when ::func is used but not when
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| 217 | GNULIB_NAMESPACE::func is used. func must be defined without overloaded
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| 218 | variants. */
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| 219 | #if defined __cplusplus && defined GNULIB_NAMESPACE
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| 220 | # define _GL_CXXALIASWARN(func) \
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| 221 | _GL_CXXALIASWARN_1 (func, GNULIB_NAMESPACE)
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| 222 | # define _GL_CXXALIASWARN_1(func,namespace) \
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| 223 | _GL_CXXALIASWARN_2 (func, namespace)
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| 224 | /* To work around GCC bug <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
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| 225 | we enable the warning only when not optimizing. */
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| 226 | # if !__OPTIMIZE__
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| 227 | # define _GL_CXXALIASWARN_2(func,namespace) \
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| 228 | _GL_WARN_ON_USE (func, \
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| 229 | "The symbol ::" #func " refers to the system function. " \
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| 230 | "Use " #namespace "::" #func " instead.")
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| 231 | # elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
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| 232 | # define _GL_CXXALIASWARN_2(func,namespace) \
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| 233 | extern __typeof__ (func) func
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| 234 | # else
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| 235 | # define _GL_CXXALIASWARN_2(func,namespace) \
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| 236 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 237 | # endif
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| 238 | #else
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| 239 | # define _GL_CXXALIASWARN(func) \
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| 240 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 241 | #endif
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| 242 |
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| 243 | /* _GL_CXXALIASWARN1 (func, rettype, parameters_and_attributes);
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| 244 | causes a warning to be emitted when the given overloaded variant of ::func
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| 245 | is used but not when GNULIB_NAMESPACE::func is used. */
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| 246 | #if defined __cplusplus && defined GNULIB_NAMESPACE
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| 247 | # define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \
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| 248 | _GL_CXXALIASWARN1_1 (func, rettype, parameters_and_attributes, \
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| 249 | GNULIB_NAMESPACE)
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| 250 | # define _GL_CXXALIASWARN1_1(func,rettype,parameters_and_attributes,namespace) \
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| 251 | _GL_CXXALIASWARN1_2 (func, rettype, parameters_and_attributes, namespace)
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| 252 | /* To work around GCC bug <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
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| 253 | we enable the warning only when not optimizing. */
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| 254 | # if !__OPTIMIZE__
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| 255 | # define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
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| 256 | _GL_WARN_ON_USE_CXX (func, rettype, parameters_and_attributes, \
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| 257 | "The symbol ::" #func " refers to the system function. " \
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| 258 | "Use " #namespace "::" #func " instead.")
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| 259 | # elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
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| 260 | # define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
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| 261 | extern __typeof__ (func) func
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| 262 | # else
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| 263 | # define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
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| 264 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 265 | # endif
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| 266 | #else
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| 267 | # define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \
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| 268 | _GL_EXTERN_C int _gl_cxxalias_dummy
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| 269 | #endif
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| 270 |
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| 271 | #endif /* _GL_CXXDEFS_H */
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