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/* C++ compatible function declaration macros.

   Copyright (C) 2010 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify it

   under the terms of the GNU General Public License as published

   by the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#ifndef _GL_CXXDEFS_H

#define _GL_CXXDEFS_H

/* The three most frequent use cases of these macros are:

   * For providing a substitute for a function that is missing on some

     platforms, but is declared and works fine on the platforms on which

     it exists:

       #if @GNULIB_FOO@

       # if !@HAVE_FOO@

       _GL_FUNCDECL_SYS (foo, ...);

       # endif

       _GL_CXXALIAS_SYS (foo, ...);

       _GL_CXXALIASWARN (foo);

       #elif defined GNULIB_POSIXCHECK

       ...

       #endif

   * For providing a replacement for a function that exists on all platforms,

     but is broken/insufficient and needs to be replaced on some platforms:

       #if @GNULIB_FOO@

       # if @REPLACE_FOO@

       #  if !(defined __cplusplus && defined GNULIB_NAMESPACE)

       #   undef foo

       #   define foo rpl_foo

       #  endif

       _GL_FUNCDECL_RPL (foo, ...);

       _GL_CXXALIAS_RPL (foo, ...);

       # else

       _GL_CXXALIAS_SYS (foo, ...);

       # endif

       _GL_CXXALIASWARN (foo);

       #elif defined GNULIB_POSIXCHECK

       ...

       #endif

   * For providing a replacement for a function that exists on some platforms

     but is broken/insufficient and needs to be replaced on some of them and

     is additionally either missing or undeclared on some other platforms:

       #if @GNULIB_FOO@

       # if @REPLACE_FOO@

       #  if !(defined __cplusplus && defined GNULIB_NAMESPACE)

       #   undef foo

       #   define foo rpl_foo

       #  endif

       _GL_FUNCDECL_RPL (foo, ...);

       _GL_CXXALIAS_RPL (foo, ...);

       # else

       #  if !@HAVE_FOO@   or   if !@HAVE_DECL_FOO@

       _GL_FUNCDECL_SYS (foo, ...);

       #  endif

       _GL_CXXALIAS_SYS (foo, ...);

       # endif

       _GL_CXXALIASWARN (foo);

       #elif defined GNULIB_POSIXCHECK

       ...

       #endif

*/

/* _GL_EXTERN_C declaration;

   performs the declaration with C linkage.  */

#if defined __cplusplus

# define _GL_EXTERN_C extern "C"

#else

# define _GL_EXTERN_C extern

#endif

/* _GL_FUNCDECL_RPL (func, rettype, parameters_and_attributes);

   declares a replacement function, named rpl_func, with the given prototype,

   consisting of return type, parameters, and attributes.

   Example:

     _GL_FUNCDECL_RPL (open, int, (const char *filename, int flags, ...)

                                  _GL_ARG_NONNULL ((1)));

 */

#define _GL_FUNCDECL_RPL(func,rettype,parameters_and_attributes) \

  _GL_FUNCDECL_RPL_1 (rpl_##func, rettype, parameters_and_attributes)

#define _GL_FUNCDECL_RPL_1(rpl_func,rettype,parameters_and_attributes) \

  _GL_EXTERN_C rettype rpl_func parameters_and_attributes

/* _GL_FUNCDECL_SYS (func, rettype, parameters_and_attributes);

   declares the system function, named func, with the given prototype,

   consisting of return type, parameters, and attributes.

   Example:

     _GL_FUNCDECL_SYS (open, int, (const char *filename, int flags, ...)

                                  _GL_ARG_NONNULL ((1)));

 */

#define _GL_FUNCDECL_SYS(func,rettype,parameters_and_attributes) \

  _GL_EXTERN_C rettype func parameters_and_attributes

/* _GL_CXXALIAS_RPL (func, rettype, parameters);

   declares a C++ alias called GNULIB_NAMESPACE::func

   that redirects to rpl_func, if GNULIB_NAMESPACE is defined.

   Example:

     _GL_CXXALIAS_RPL (open, int, (const char *filename, int flags, ...));

 */

#define _GL_CXXALIAS_RPL(func,rettype,parameters) \

  _GL_CXXALIAS_RPL_1 (func, rpl_##func, rettype, parameters)

#if defined __cplusplus && defined GNULIB_NAMESPACE

# define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \

    namespace GNULIB_NAMESPACE                                \

    {                                                         \

      rettype (*const func) parameters = ::rpl_func;          \

    }                                                         \

    _GL_EXTERN_C int _gl_cxxalias_dummy

#else

# define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \

    _GL_EXTERN_C int _gl_cxxalias_dummy

#endif

/* _GL_CXXALIAS_RPL_CAST_1 (func, rpl_func, rettype, parameters);

   is like  _GL_CXXALIAS_RPL_1 (func, rpl_func, rettype, parameters);

   except that the C function rpl_func may have a slightly different

   declaration.  A cast is used to silence the "invalid conversion" error

   that would otherwise occur.  */

#if defined __cplusplus && defined GNULIB_NAMESPACE

# define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \

    namespace GNULIB_NAMESPACE                                     \

    {                                                              \

      rettype (*const func) parameters =                           \

        reinterpret_cast<rettype(*)parameters>(::rpl_func);        \

    }                                                              \

    _GL_EXTERN_C int _gl_cxxalias_dummy

#else

# define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \

    _GL_EXTERN_C int _gl_cxxalias_dummy

#endif

/* _GL_CXXALIAS_SYS (func, rettype, parameters);

   declares a C++ alias called GNULIB_NAMESPACE::func

   that redirects to the system provided function func, if GNULIB_NAMESPACE

   is defined.

   Example:

     _GL_CXXALIAS_SYS (open, int, (const char *filename, int flags, ...));

 */

#if defined __cplusplus && defined GNULIB_NAMESPACE

  /* If we were to write

       rettype (*const func) parameters = ::func;

     like above in _GL_CXXALIAS_RPL_1, the compiler could optimize calls

     better (remove an indirection through a 'static' pointer variable),

     but then the _GL_CXXALIASWARN macro below would cause a warning not only

     for uses of ::func but also for uses of GNULIB_NAMESPACE::func.  */

# define _GL_CXXALIAS_SYS(func,rettype,parameters) \

    namespace GNULIB_NAMESPACE                     \

    {                                              \

      static rettype (*func) parameters = ::func;  \

    }                                              \

    _GL_EXTERN_C int _gl_cxxalias_dummy

#else

# define _GL_CXXALIAS_SYS(func,rettype,parameters) \

    _GL_EXTERN_C int _gl_cxxalias_dummy

#endif

/* _GL_CXXALIAS_SYS_CAST (func, rettype, parameters);

   is like  _GL_CXXALIAS_SYS (func, rettype, parameters);

   except that the C function func may have a slightly different declaration.

   A cast is used to silence the "invalid conversion" error that would

   otherwise occur.  */

#if defined __cplusplus && defined GNULIB_NAMESPACE

# define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \

    namespace GNULIB_NAMESPACE                          \

    {                                                   \

      static rettype (*func) parameters =               \

        reinterpret_cast<rettype(*)parameters>(::func); \

    }                                                   \

    _GL_EXTERN_C int _gl_cxxalias_dummy

#else

# define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \

    _GL_EXTERN_C int _gl_cxxalias_dummy

#endif

/* _GL_CXXALIAS_SYS_CAST2 (func, rettype, parameters, rettype2, parameters2);

   is like  _GL_CXXALIAS_SYS (func, rettype, parameters);

   except that the C function is picked among a set of overloaded functions,

   namely the one with rettype2 and parameters2.  Two consecutive casts

   are used to silence the "cannot find a match" and "invalid conversion"

   errors that would otherwise occur.  */

#if defined __cplusplus && defined GNULIB_NAMESPACE

  /* The outer cast must be a reinterpret_cast.

     The inner cast: When the function is defined as a set of overloaded

     functions, it works as a static_cast<>, choosing the designated variant.

     When the function is defined as a single variant, it works as a

     reinterpret_cast<>. The parenthesized cast syntax works both ways.  */

# define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \

    namespace GNULIB_NAMESPACE                                                \

    {                                                                         \

      static rettype (*func) parameters =                                     \

        reinterpret_cast<rettype(*)parameters>(                               \

          (rettype2(*)parameters2)(::func));                                  \

    }                                                                         \

    _GL_EXTERN_C int _gl_cxxalias_dummy

#else

# define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \

    _GL_EXTERN_C int _gl_cxxalias_dummy

#endif

/* _GL_CXXALIASWARN (func);

   causes a warning to be emitted when ::func is used but not when

   GNULIB_NAMESPACE::func is used.  func must be defined without overloaded

   variants.  */

#if defined __cplusplus && defined GNULIB_NAMESPACE

# define _GL_CXXALIASWARN(func) \

   _GL_CXXALIASWARN_1 (func, GNULIB_NAMESPACE)

# define _GL_CXXALIASWARN_1(func,namespace) \

   _GL_CXXALIASWARN_2 (func, namespace)

/* To work around GCC bug <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,

   we enable the warning only when not optimizing.  */

# if !__OPTIMIZE__

#  define _GL_CXXALIASWARN_2(func,namespace) \

    _GL_WARN_ON_USE (func, \

                     "The symbol ::" #func " refers to the system function. " \

                     "Use " #namespace "::" #func " instead.")

# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING

#  define _GL_CXXALIASWARN_2(func,namespace) \

     extern __typeof__ (func) func

# else

#  define _GL_CXXALIASWARN_2(func,namespace) \

     _GL_EXTERN_C int _gl_cxxalias_dummy

# endif

#else

# define _GL_CXXALIASWARN(func) \

    _GL_EXTERN_C int _gl_cxxalias_dummy

#endif

/* _GL_CXXALIASWARN1 (func, rettype, parameters_and_attributes);

   causes a warning to be emitted when the given overloaded variant of ::func

   is used but not when GNULIB_NAMESPACE::func is used.  */

#if defined __cplusplus && defined GNULIB_NAMESPACE

# define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \

   _GL_CXXALIASWARN1_1 (func, rettype, parameters_and_attributes, \

                        GNULIB_NAMESPACE)

# define _GL_CXXALIASWARN1_1(func,rettype,parameters_and_attributes,namespace) \

   _GL_CXXALIASWARN1_2 (func, rettype, parameters_and_attributes, namespace)

/* To work around GCC bug <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,

   we enable the warning only when not optimizing.  */

# if !__OPTIMIZE__

#  define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \

    _GL_WARN_ON_USE_CXX (func, rettype, parameters_and_attributes, \

                         "The symbol ::" #func " refers to the system function. " \

                         "Use " #namespace "::" #func " instead.")

# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING

#  define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \

     extern __typeof__ (func) func

# else

#  define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \

     _GL_EXTERN_C int _gl_cxxalias_dummy

# endif

#else

# define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \

    _GL_EXTERN_C int _gl_cxxalias_dummy

#endif

#endif /* _GL_CXXDEFS_H */