c++defs.h

Last change on this file was 3529, checked in by bird, 3 years ago
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1	/* C++ compatible function declaration macros.
2	Copyright (C) 2010-2021 Free Software Foundation, Inc.
3
4	This program is free software: you can redistribute it and/or modify it
5	under the terms of the GNU Lesser General Public License as published
6	by the Free Software Foundation; either version 2 of the License, or
7	(at your option) any later version.
8
9	This program is distributed in the hope that it will be useful,
10	but WITHOUT ANY WARRANTY; without even the implied warranty of
11	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12	Lesser General Public License for more details.
13
14	You should have received a copy of the GNU Lesser General Public License
15	along with this program. If not, see <https://www.gnu.org/licenses/>. */
16
17	#ifndef _GL_CXXDEFS_H
18	#define _GL_CXXDEFS_H
19
20	/* Begin/end the GNULIB_NAMESPACE namespace. */
21	#if defined __cplusplus && defined GNULIB_NAMESPACE
22	# define _GL_BEGIN_NAMESPACE namespace GNULIB_NAMESPACE {
23	# define _GL_END_NAMESPACE }
24	#else
25	# define _GL_BEGIN_NAMESPACE
26	# define _GL_END_NAMESPACE
27	#endif
28
29	/* The three most frequent use cases of these macros are:
30
31	* For providing a substitute for a function that is missing on some
32	platforms, but is declared and works fine on the platforms on which
33	it exists:
34
35	#if @GNULIB_FOO@
36	# if !@HAVE_FOO@
37	_GL_FUNCDECL_SYS (foo, ...);
38	# endif
39	_GL_CXXALIAS_SYS (foo, ...);
40	_GL_CXXALIASWARN (foo);
41	#elif defined GNULIB_POSIXCHECK
42	...
43	#endif
44
45	* For providing a replacement for a function that exists on all platforms,
46	but is broken/insufficient and needs to be replaced on some platforms:
47
48	#if @GNULIB_FOO@
49	# if @REPLACE_FOO@
50	# if !(defined __cplusplus && defined GNULIB_NAMESPACE)
51	# undef foo
52	# define foo rpl_foo
53	# endif
54	_GL_FUNCDECL_RPL (foo, ...);
55	_GL_CXXALIAS_RPL (foo, ...);
56	# else
57	_GL_CXXALIAS_SYS (foo, ...);
58	# endif
59	_GL_CXXALIASWARN (foo);
60	#elif defined GNULIB_POSIXCHECK
61	...
62	#endif
63
64	* For providing a replacement for a function that exists on some platforms
65	but is broken/insufficient and needs to be replaced on some of them and
66	is additionally either missing or undeclared on some other platforms:
67
68	#if @GNULIB_FOO@
69	# if @REPLACE_FOO@
70	# if !(defined __cplusplus && defined GNULIB_NAMESPACE)
71	# undef foo
72	# define foo rpl_foo
73	# endif
74	_GL_FUNCDECL_RPL (foo, ...);
75	_GL_CXXALIAS_RPL (foo, ...);
76	# else
77	# if !@HAVE_FOO@ or if !@HAVE_DECL_FOO@
78	_GL_FUNCDECL_SYS (foo, ...);
79	# endif
80	_GL_CXXALIAS_SYS (foo, ...);
81	# endif
82	_GL_CXXALIASWARN (foo);
83	#elif defined GNULIB_POSIXCHECK
84	...
85	#endif
86	*/
87
88	/* _GL_EXTERN_C declaration;
89	performs the declaration with C linkage. */
90	#if defined __cplusplus
91	# define _GL_EXTERN_C extern "C"
92	#else
93	# define _GL_EXTERN_C extern
94	#endif
95
96	/* _GL_FUNCDECL_RPL (func, rettype, parameters_and_attributes);
97	declares a replacement function, named rpl_func, with the given prototype,
98	consisting of return type, parameters, and attributes.
99	Example:
100	_GL_FUNCDECL_RPL (open, int, (const char *filename, int flags, ...)
101	_GL_ARG_NONNULL ((1)));
102	*/
103	#define _GL_FUNCDECL_RPL(func,rettype,parameters_and_attributes) \
104	_GL_FUNCDECL_RPL_1 (rpl_##func, rettype, parameters_and_attributes)
105	#define _GL_FUNCDECL_RPL_1(rpl_func,rettype,parameters_and_attributes) \
106	_GL_EXTERN_C rettype rpl_func parameters_and_attributes
107
108	/* _GL_FUNCDECL_SYS (func, rettype, parameters_and_attributes);
109	declares the system function, named func, with the given prototype,
110	consisting of return type, parameters, and attributes.
111	Example:
112	_GL_FUNCDECL_SYS (open, int, (const char *filename, int flags, ...)
113	_GL_ARG_NONNULL ((1)));
114	*/
115	#define _GL_FUNCDECL_SYS(func,rettype,parameters_and_attributes) \
116	_GL_EXTERN_C rettype func parameters_and_attributes
117
118	/* _GL_CXXALIAS_RPL (func, rettype, parameters);
119	declares a C++ alias called GNULIB_NAMESPACE::func
120	that redirects to rpl_func, if GNULIB_NAMESPACE is defined.
121	Example:
122	_GL_CXXALIAS_RPL (open, int, (const char *filename, int flags, ...));
123
124	Wrapping rpl_func in an object with an inline conversion operator
125	avoids a reference to rpl_func unless GNULIB_NAMESPACE::func is
126	actually used in the program. */
127	#define _GL_CXXALIAS_RPL(func,rettype,parameters) \
128	_GL_CXXALIAS_RPL_1 (func, rpl_##func, rettype, parameters)
129	#if defined __cplusplus && defined GNULIB_NAMESPACE
130	# define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \
131	namespace GNULIB_NAMESPACE \
132	{ \
133	static const struct _gl_ ## func ## _wrapper \
134	{ \
135	typedef rettype (*type) parameters; \
136	\
137	inline operator type () const \
138	{ \
139	return ::rpl_func; \
140	} \
141	} func = {}; \
142	} \
143	_GL_EXTERN_C int _gl_cxxalias_dummy
144	#else
145	# define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \
146	_GL_EXTERN_C int _gl_cxxalias_dummy
147	#endif
148
149	/* _GL_CXXALIAS_MDA (func, rettype, parameters);
150	is to be used when func is a Microsoft deprecated alias, on native Windows.
151	It declares a C++ alias called GNULIB_NAMESPACE::func
152	that redirects to _func, if GNULIB_NAMESPACE is defined.
153	Example:
154	_GL_CXXALIAS_MDA (open, int, (const char *filename, int flags, ...));
155	*/
156	#define _GL_CXXALIAS_MDA(func,rettype,parameters) \
157	_GL_CXXALIAS_RPL_1 (func, _##func, rettype, parameters)
158
159	/* _GL_CXXALIAS_RPL_CAST_1 (func, rpl_func, rettype, parameters);
160	is like _GL_CXXALIAS_RPL_1 (func, rpl_func, rettype, parameters);
161	except that the C function rpl_func may have a slightly different
162	declaration. A cast is used to silence the "invalid conversion" error
163	that would otherwise occur. */
164	#if defined __cplusplus && defined GNULIB_NAMESPACE
165	# define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \
166	namespace GNULIB_NAMESPACE \
167	{ \
168	static const struct _gl_ ## func ## _wrapper \
169	{ \
170	typedef rettype (*type) parameters; \
171	\
172	inline operator type () const \
173	{ \
174	return reinterpret_cast<type>(::rpl_func); \
175	} \
176	} func = {}; \
177	} \
178	_GL_EXTERN_C int _gl_cxxalias_dummy
179	#else
180	# define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \
181	_GL_EXTERN_C int _gl_cxxalias_dummy
182	#endif
183
184	/* _GL_CXXALIAS_MDA_CAST (func, rettype, parameters);
185	is like _GL_CXXALIAS_MDA (func, rettype, parameters);
186	except that the C function func may have a slightly different declaration.
187	A cast is used to silence the "invalid conversion" error that would
188	otherwise occur. */
189	#define _GL_CXXALIAS_MDA_CAST(func,rettype,parameters) \
190	_GL_CXXALIAS_RPL_CAST_1 (func, _##func, rettype, parameters)
191
192	/* _GL_CXXALIAS_SYS (func, rettype, parameters);
193	declares a C++ alias called GNULIB_NAMESPACE::func
194	that redirects to the system provided function func, if GNULIB_NAMESPACE
195	is defined.
196	Example:
197	_GL_CXXALIAS_SYS (open, int, (const char *filename, int flags, ...));
198
199	Wrapping func in an object with an inline conversion operator
200	avoids a reference to func unless GNULIB_NAMESPACE::func is
201	actually used in the program. */
202	#if defined __cplusplus && defined GNULIB_NAMESPACE
203	# define _GL_CXXALIAS_SYS(func,rettype,parameters) \
204	namespace GNULIB_NAMESPACE \
205	{ \
206	static const struct _gl_ ## func ## _wrapper \
207	{ \
208	typedef rettype (*type) parameters; \
209	\
210	inline operator type () const \
211	{ \
212	return ::func; \
213	} \
214	} func = {}; \
215	} \
216	_GL_EXTERN_C int _gl_cxxalias_dummy
217	#else
218	# define _GL_CXXALIAS_SYS(func,rettype,parameters) \
219	_GL_EXTERN_C int _gl_cxxalias_dummy
220	#endif
221
222	/* _GL_CXXALIAS_SYS_CAST (func, rettype, parameters);
223	is like _GL_CXXALIAS_SYS (func, rettype, parameters);
224	except that the C function func may have a slightly different declaration.
225	A cast is used to silence the "invalid conversion" error that would
226	otherwise occur. */
227	#if defined __cplusplus && defined GNULIB_NAMESPACE
228	# define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \
229	namespace GNULIB_NAMESPACE \
230	{ \
231	static const struct _gl_ ## func ## _wrapper \
232	{ \
233	typedef rettype (*type) parameters; \
234	\
235	inline operator type () const \
236	{ \
237	return reinterpret_cast<type>(::func); \
238	} \
239	} func = {}; \
240	} \
241	_GL_EXTERN_C int _gl_cxxalias_dummy
242	#else
243	# define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \
244	_GL_EXTERN_C int _gl_cxxalias_dummy
245	#endif
246
247	/* _GL_CXXALIAS_SYS_CAST2 (func, rettype, parameters, rettype2, parameters2);
248	is like _GL_CXXALIAS_SYS (func, rettype, parameters);
249	except that the C function is picked among a set of overloaded functions,
250	namely the one with rettype2 and parameters2. Two consecutive casts
251	are used to silence the "cannot find a match" and "invalid conversion"
252	errors that would otherwise occur. */
253	#if defined __cplusplus && defined GNULIB_NAMESPACE
254	/* The outer cast must be a reinterpret_cast.
255	The inner cast: When the function is defined as a set of overloaded
256	functions, it works as a static_cast<>, choosing the designated variant.
257	When the function is defined as a single variant, it works as a
258	reinterpret_cast<>. The parenthesized cast syntax works both ways. */
259	# define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \
260	namespace GNULIB_NAMESPACE \
261	{ \
262	static const struct _gl_ ## func ## _wrapper \
263	{ \
264	typedef rettype (*type) parameters; \
265	\
266	inline operator type () const \
267	{ \
268	return reinterpret_cast<type>((rettype2 (*) parameters2)(::func)); \
269	} \
270	} func = {}; \
271	} \
272	_GL_EXTERN_C int _gl_cxxalias_dummy
273	#else
274	# define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \
275	_GL_EXTERN_C int _gl_cxxalias_dummy
276	#endif
277
278	/* _GL_CXXALIASWARN (func);
279	causes a warning to be emitted when ::func is used but not when
280	GNULIB_NAMESPACE::func is used. func must be defined without overloaded
281	variants. */
282	#if defined __cplusplus && defined GNULIB_NAMESPACE
283	# define _GL_CXXALIASWARN(func) \
284	_GL_CXXALIASWARN_1 (func, GNULIB_NAMESPACE)
285	# define _GL_CXXALIASWARN_1(func,namespace) \
286	_GL_CXXALIASWARN_2 (func, namespace)
287	/* To work around GCC bug <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
288	we enable the warning only when not optimizing. */
289	# if !(defined __GNUC__ && !defined __clang__ && __OPTIMIZE__)
290	# define _GL_CXXALIASWARN_2(func,namespace) \
291	_GL_WARN_ON_USE (func, \
292	"The symbol ::" #func " refers to the system function. " \
293	"Use " #namespace "::" #func " instead.")
294	# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
295	# define _GL_CXXALIASWARN_2(func,namespace) \
296	extern __typeof__ (func) func
297	# else
298	# define _GL_CXXALIASWARN_2(func,namespace) \
299	_GL_EXTERN_C int _gl_cxxalias_dummy
300	# endif
301	#else
302	# define _GL_CXXALIASWARN(func) \
303	_GL_EXTERN_C int _gl_cxxalias_dummy
304	#endif
305
306	/* _GL_CXXALIASWARN1 (func, rettype, parameters_and_attributes);
307	causes a warning to be emitted when the given overloaded variant of ::func
308	is used but not when GNULIB_NAMESPACE::func is used. */
309	#if defined __cplusplus && defined GNULIB_NAMESPACE
310	# define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \
311	_GL_CXXALIASWARN1_1 (func, rettype, parameters_and_attributes, \
312	GNULIB_NAMESPACE)
313	# define _GL_CXXALIASWARN1_1(func,rettype,parameters_and_attributes,namespace) \
314	_GL_CXXALIASWARN1_2 (func, rettype, parameters_and_attributes, namespace)
315	/* To work around GCC bug <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
316	we enable the warning only when not optimizing. */
317	# if !(defined __GNUC__ && !defined __clang__ && __OPTIMIZE__)
318	# define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
319	_GL_WARN_ON_USE_CXX (func, rettype, rettype, parameters_and_attributes, \
320	"The symbol ::" #func " refers to the system function. " \
321	"Use " #namespace "::" #func " instead.")
322	# else
323	# define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
324	_GL_EXTERN_C int _gl_cxxalias_dummy
325	# endif
326	#else
327	# define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \
328	_GL_EXTERN_C int _gl_cxxalias_dummy
329	#endif
330
331	#endif /* _GL_CXXDEFS_H */

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source: kBuild/vendor/grep/current/gnulib-tests/c++defs.h

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