dhcpd-pools
3.0
ISC dhcpd lease usage analyser
lib
c++defs.h
Go to the documentation of this file.
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/* C++ compatible function declaration macros.
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Copyright (C) 2010-2017 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published
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by the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#ifndef _GL_CXXDEFS_H
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#define _GL_CXXDEFS_H
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/* Begin/end the GNULIB_NAMESPACE namespace. */
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#if defined __cplusplus && defined GNULIB_NAMESPACE
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# define _GL_BEGIN_NAMESPACE namespace GNULIB_NAMESPACE {
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# define _GL_END_NAMESPACE }
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#else
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# define _GL_BEGIN_NAMESPACE
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# define _GL_END_NAMESPACE
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#endif
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/* The three most frequent use cases of these macros are:
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* For providing a substitute for a function that is missing on some
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platforms, but is declared and works fine on the platforms on which
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it exists:
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#if @GNULIB_FOO@
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# if !@HAVE_FOO@
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_GL_FUNCDECL_SYS (foo, ...);
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# endif
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_GL_CXXALIAS_SYS (foo, ...);
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_GL_CXXALIASWARN (foo);
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#elif defined GNULIB_POSIXCHECK
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...
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#endif
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* For providing a replacement for a function that exists on all platforms,
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but is broken/insufficient and needs to be replaced on some platforms:
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#if @GNULIB_FOO@
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# if @REPLACE_FOO@
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# if !(defined __cplusplus && defined GNULIB_NAMESPACE)
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# undef foo
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# define foo rpl_foo
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# endif
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_GL_FUNCDECL_RPL (foo, ...);
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_GL_CXXALIAS_RPL (foo, ...);
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# else
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_GL_CXXALIAS_SYS (foo, ...);
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# endif
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_GL_CXXALIASWARN (foo);
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#elif defined GNULIB_POSIXCHECK
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...
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#endif
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* For providing a replacement for a function that exists on some platforms
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but is broken/insufficient and needs to be replaced on some of them and
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is additionally either missing or undeclared on some other platforms:
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#if @GNULIB_FOO@
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# if @REPLACE_FOO@
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# if !(defined __cplusplus && defined GNULIB_NAMESPACE)
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# undef foo
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# define foo rpl_foo
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# endif
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_GL_FUNCDECL_RPL (foo, ...);
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_GL_CXXALIAS_RPL (foo, ...);
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# else
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# if !@HAVE_FOO@ or if !@HAVE_DECL_FOO@
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_GL_FUNCDECL_SYS (foo, ...);
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# endif
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_GL_CXXALIAS_SYS (foo, ...);
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# endif
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_GL_CXXALIASWARN (foo);
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#elif defined GNULIB_POSIXCHECK
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...
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#endif
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*/
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/* _GL_EXTERN_C declaration;
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performs the declaration with C linkage. */
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#if defined __cplusplus
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# define _GL_EXTERN_C extern "C"
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#else
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# define _GL_EXTERN_C extern
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#endif
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/* _GL_FUNCDECL_RPL (func, rettype, parameters_and_attributes);
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declares a replacement function, named rpl_func, with the given prototype,
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consisting of return type, parameters, and attributes.
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Example:
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_GL_FUNCDECL_RPL (open, int, (const char *filename, int flags, ...)
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_GL_ARG_NONNULL ((1)));
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*/
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#define _GL_FUNCDECL_RPL(func,rettype,parameters_and_attributes) \
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_GL_FUNCDECL_RPL_1 (rpl_##func, rettype, parameters_and_attributes)
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#define _GL_FUNCDECL_RPL_1(rpl_func,rettype,parameters_and_attributes) \
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_GL_EXTERN_C rettype rpl_func parameters_and_attributes
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/* _GL_FUNCDECL_SYS (func, rettype, parameters_and_attributes);
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declares the system function, named func, with the given prototype,
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consisting of return type, parameters, and attributes.
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Example:
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_GL_FUNCDECL_SYS (open, int, (const char *filename, int flags, ...)
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_GL_ARG_NONNULL ((1)));
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*/
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#define _GL_FUNCDECL_SYS(func,rettype,parameters_and_attributes) \
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_GL_EXTERN_C rettype func parameters_and_attributes
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/* _GL_CXXALIAS_RPL (func, rettype, parameters);
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declares a C++ alias called GNULIB_NAMESPACE::func
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that redirects to rpl_func, if GNULIB_NAMESPACE is defined.
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Example:
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_GL_CXXALIAS_RPL (open, int, (const char *filename, int flags, ...));
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Wrapping rpl_func in an object with an inline conversion operator
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avoids a reference to rpl_func unless GNULIB_NAMESPACE::func is
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actually used in the program. */
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#define _GL_CXXALIAS_RPL(func,rettype,parameters) \
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_GL_CXXALIAS_RPL_1 (func, rpl_##func, rettype, parameters)
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#if defined __cplusplus && defined GNULIB_NAMESPACE
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# define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \
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namespace GNULIB_NAMESPACE \
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{ \
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static const struct _gl_ ## func ## _wrapper \
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{ \
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typedef rettype (*type) parameters; \
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\
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inline operator type () const \
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{ \
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return ::rpl_func; \
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} \
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} func = {}; \
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} \
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_GL_EXTERN_C int _gl_cxxalias_dummy
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#else
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# define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \
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_GL_EXTERN_C int _gl_cxxalias_dummy
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#endif
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/* _GL_CXXALIAS_RPL_CAST_1 (func, rpl_func, rettype, parameters);
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is like _GL_CXXALIAS_RPL_1 (func, rpl_func, rettype, parameters);
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except that the C function rpl_func may have a slightly different
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declaration. A cast is used to silence the "invalid conversion" error
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that would otherwise occur. */
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#if defined __cplusplus && defined GNULIB_NAMESPACE
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# define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \
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namespace GNULIB_NAMESPACE \
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{ \
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static const struct _gl_ ## func ## _wrapper \
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{ \
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typedef rettype (*type) parameters; \
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\
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inline operator type () const \
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{ \
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return reinterpret_cast<type>(::rpl_func); \
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} \
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} func = {}; \
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} \
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_GL_EXTERN_C int _gl_cxxalias_dummy
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#else
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# define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \
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_GL_EXTERN_C int _gl_cxxalias_dummy
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#endif
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/* _GL_CXXALIAS_SYS (func, rettype, parameters);
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declares a C++ alias called GNULIB_NAMESPACE::func
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that redirects to the system provided function func, if GNULIB_NAMESPACE
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is defined.
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Example:
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_GL_CXXALIAS_SYS (open, int, (const char *filename, int flags, ...));
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Wrapping func in an object with an inline conversion operator
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avoids a reference to func unless GNULIB_NAMESPACE::func is
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actually used in the program. */
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#if defined __cplusplus && defined GNULIB_NAMESPACE
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# define _GL_CXXALIAS_SYS(func,rettype,parameters) \
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namespace GNULIB_NAMESPACE \
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{ \
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static const struct _gl_ ## func ## _wrapper \
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{ \
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typedef rettype (*type) parameters; \
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\
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inline operator type () const \
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{ \
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return ::func; \
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} \
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} func = {}; \
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} \
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_GL_EXTERN_C int _gl_cxxalias_dummy
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#else
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# define _GL_CXXALIAS_SYS(func,rettype,parameters) \
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_GL_EXTERN_C int _gl_cxxalias_dummy
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#endif
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/* _GL_CXXALIAS_SYS_CAST (func, rettype, parameters);
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is like _GL_CXXALIAS_SYS (func, rettype, parameters);
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except that the C function func may have a slightly different declaration.
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A cast is used to silence the "invalid conversion" error that would
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otherwise occur. */
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#if defined __cplusplus && defined GNULIB_NAMESPACE
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# define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \
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namespace GNULIB_NAMESPACE \
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{ \
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static const struct _gl_ ## func ## _wrapper \
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{ \
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typedef rettype (*type) parameters; \
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\
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inline operator type () const \
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{ \
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return reinterpret_cast<type>(::func); \
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} \
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} func = {}; \
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} \
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_GL_EXTERN_C int _gl_cxxalias_dummy
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#else
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# define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \
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_GL_EXTERN_C int _gl_cxxalias_dummy
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#endif
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/* _GL_CXXALIAS_SYS_CAST2 (func, rettype, parameters, rettype2, parameters2);
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is like _GL_CXXALIAS_SYS (func, rettype, parameters);
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except that the C function is picked among a set of overloaded functions,
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namely the one with rettype2 and parameters2. Two consecutive casts
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are used to silence the "cannot find a match" and "invalid conversion"
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errors that would otherwise occur. */
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#if defined __cplusplus && defined GNULIB_NAMESPACE
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/* The outer cast must be a reinterpret_cast.
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The inner cast: When the function is defined as a set of overloaded
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functions, it works as a static_cast<>, choosing the designated variant.
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When the function is defined as a single variant, it works as a
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reinterpret_cast<>. The parenthesized cast syntax works both ways. */
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# define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \
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namespace GNULIB_NAMESPACE \
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{ \
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static const struct _gl_ ## func ## _wrapper \
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{ \
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typedef rettype (*type) parameters; \
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\
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inline operator type () const \
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{ \
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return reinterpret_cast<type>((rettype2 (*) parameters2)(::func)); \
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} \
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} func = {}; \
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} \
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_GL_EXTERN_C int _gl_cxxalias_dummy
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#else
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# define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \
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_GL_EXTERN_C int _gl_cxxalias_dummy
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#endif
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/* _GL_CXXALIASWARN (func);
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causes a warning to be emitted when ::func is used but not when
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GNULIB_NAMESPACE::func is used. func must be defined without overloaded
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variants. */
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#if defined __cplusplus && defined GNULIB_NAMESPACE
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# define _GL_CXXALIASWARN(func) \
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_GL_CXXALIASWARN_1 (func, GNULIB_NAMESPACE)
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# define _GL_CXXALIASWARN_1(func,namespace) \
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_GL_CXXALIASWARN_2 (func, namespace)
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/* To work around GCC bug <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
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we enable the warning only when not optimizing. */
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# if !__OPTIMIZE__
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# define _GL_CXXALIASWARN_2(func,namespace) \
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_GL_WARN_ON_USE (func, \
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"The symbol ::" #func " refers to the system function. " \
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"Use " #namespace "::" #func " instead.")
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# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
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# define _GL_CXXALIASWARN_2(func,namespace) \
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extern __typeof__ (func) func
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# else
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# define _GL_CXXALIASWARN_2(func,namespace) \
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_GL_EXTERN_C int _gl_cxxalias_dummy
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# endif
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#else
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# define _GL_CXXALIASWARN(func) \
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_GL_EXTERN_C int _gl_cxxalias_dummy
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#endif
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/* _GL_CXXALIASWARN1 (func, rettype, parameters_and_attributes);
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causes a warning to be emitted when the given overloaded variant of ::func
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is used but not when GNULIB_NAMESPACE::func is used. */
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#if defined __cplusplus && defined GNULIB_NAMESPACE
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# define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \
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_GL_CXXALIASWARN1_1 (func, rettype, parameters_and_attributes, \
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GNULIB_NAMESPACE)
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# define _GL_CXXALIASWARN1_1(func,rettype,parameters_and_attributes,namespace) \
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_GL_CXXALIASWARN1_2 (func, rettype, parameters_and_attributes, namespace)
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/* To work around GCC bug <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
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we enable the warning only when not optimizing. */
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# if !__OPTIMIZE__
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# define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
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_GL_WARN_ON_USE_CXX (func, rettype, parameters_and_attributes, \
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"The symbol ::" #func " refers to the system function. " \
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"Use " #namespace "::" #func " instead.")
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# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
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# define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
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extern __typeof__ (func) func
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# else
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# define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
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_GL_EXTERN_C int _gl_cxxalias_dummy
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# endif
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#else
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# define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \
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_GL_EXTERN_C int _gl_cxxalias_dummy
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#endif
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#endif
/* _GL_CXXDEFS_H */
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