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emacs/lib/c++defs.h
Paul Eggert ba05d005e5 Update copyright year to 2021 
Run "TZ=UTC0 admin/update-copyright".
2021-01-01 01:13:56 -08:00

332 lines
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/* C++ compatible function declaration macros.
Copyright (C) 2010-2021 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
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 <https://www.gnu.org/licenses/>. */
#ifndef _GL_CXXDEFS_H
#define _GL_CXXDEFS_H
/* Begin/end the GNULIB_NAMESPACE namespace. */
#if defined __cplusplus && defined GNULIB_NAMESPACE
# define _GL_BEGIN_NAMESPACE namespace GNULIB_NAMESPACE {
# define _GL_END_NAMESPACE }
#else
# define _GL_BEGIN_NAMESPACE
# define _GL_END_NAMESPACE
#endif
/* 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, ...));
Wrapping rpl_func in an object with an inline conversion operator
avoids a reference to rpl_func unless GNULIB_NAMESPACE::func is
actually used in the program. */
#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 \
{ \
static const struct _gl_ ## func ## _wrapper \
{ \
typedef rettype (*type) parameters; \
\
inline operator type () const \
{ \
return ::rpl_func; \
} \
} 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_MDA (func, rettype, parameters);
is to be used when func is a Microsoft deprecated alias, on native Windows.
It declares a C++ alias called GNULIB_NAMESPACE::func
that redirects to _func, if GNULIB_NAMESPACE is defined.
Example:
_GL_CXXALIAS_MDA (open, int, (const char *filename, int flags, ...));
*/
#define _GL_CXXALIAS_MDA(func,rettype,parameters) \
_GL_CXXALIAS_RPL_1 (func, _##func, rettype, parameters)
/* _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 \
{ \
static const struct _gl_ ## func ## _wrapper \
{ \
typedef rettype (*type) parameters; \
\
inline operator type () const \
{ \
return reinterpret_cast<type>(::rpl_func); \
} \
} 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_MDA_CAST (func, rettype, parameters);
is like _GL_CXXALIAS_MDA (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. */
#define _GL_CXXALIAS_MDA_CAST(func,rettype,parameters) \
_GL_CXXALIAS_RPL_CAST_1 (func, _##func, rettype, parameters)
/* _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, ...));
Wrapping func in an object with an inline conversion operator
avoids a reference to func unless GNULIB_NAMESPACE::func is
actually used in the program. */
#if defined __cplusplus && defined GNULIB_NAMESPACE
# define _GL_CXXALIAS_SYS(func,rettype,parameters) \
namespace GNULIB_NAMESPACE \
{ \
static const struct _gl_ ## func ## _wrapper \
{ \
typedef rettype (*type) parameters; \
\
inline operator type () const \
{ \
return ::func; \
} \
} 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 const struct _gl_ ## func ## _wrapper \
{ \
typedef rettype (*type) parameters; \
\
inline operator type () const \
{ \
return reinterpret_cast<type>(::func); \
} \
} 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 const struct _gl_ ## func ## _wrapper \
{ \
typedef rettype (*type) parameters; \
\
inline operator type () const \
{ \
return reinterpret_cast<type>((rettype2 (*) parameters2)(::func)); \
} \
} 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 <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
we enable the warning only when not optimizing. */
# if !(defined __GNUC__ && !defined __clang__ && __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 <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
we enable the warning only when not optimizing. */
# if !(defined __GNUC__ && !defined __clang__ && __OPTIMIZE__)
# define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
_GL_WARN_ON_USE_CXX (func, rettype, rettype, parameters_and_attributes, \
"The symbol ::" #func " refers to the system function. " \
"Use " #namespace "::" #func " instead.")
# 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 */
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