1: /* C++ compatible function declaration macros.
2: Copyright (C) 2010-2019 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 General Public License as published
6: by the Free Software Foundation; either version 3 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: General Public License for more details.
13:
14: You should have received a copy of the GNU 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_RPL_CAST_1 (func, rpl_func, rettype, parameters);
150: is like _GL_CXXALIAS_RPL_1 (func, rpl_func, rettype, parameters);
151: except that the C function rpl_func may have a slightly different
152: declaration. A cast is used to silence the "invalid conversion" error
153: that would otherwise occur. */
154: #if defined __cplusplus && defined GNULIB_NAMESPACE
155: # define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \
156: namespace GNULIB_NAMESPACE \
157: { \
158: static const struct _gl_ ## func ## _wrapper \
159: { \
160: typedef rettype (*type) parameters; \
161: \
162: inline operator type () const \
163: { \
164: return reinterpret_cast<type>(::rpl_func); \
165: } \
166: } func = {}; \
167: } \
168: _GL_EXTERN_C int _gl_cxxalias_dummy
169: #else
170: # define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \
171: _GL_EXTERN_C int _gl_cxxalias_dummy
172: #endif
173:
174: /* _GL_CXXALIAS_SYS (func, rettype, parameters);
175: declares a C++ alias called GNULIB_NAMESPACE::func
176: that redirects to the system provided function func, if GNULIB_NAMESPACE
177: is defined.
178: Example:
179: _GL_CXXALIAS_SYS (open, int, (const char *filename, int flags, ...));
180:
181: Wrapping func in an object with an inline conversion operator
182: avoids a reference to func unless GNULIB_NAMESPACE::func is
183: actually used in the program. */
184: #if defined __cplusplus && defined GNULIB_NAMESPACE
185: # define _GL_CXXALIAS_SYS(func,rettype,parameters) \
186: namespace GNULIB_NAMESPACE \
187: { \
188: static const struct _gl_ ## func ## _wrapper \
189: { \
190: typedef rettype (*type) parameters; \
191: \
192: inline operator type () const \
193: { \
194: return ::func; \
195: } \
196: } func = {}; \
197: } \
198: _GL_EXTERN_C int _gl_cxxalias_dummy
199: #else
200: # define _GL_CXXALIAS_SYS(func,rettype,parameters) \
201: _GL_EXTERN_C int _gl_cxxalias_dummy
202: #endif
203:
204: /* _GL_CXXALIAS_SYS_CAST (func, rettype, parameters);
205: is like _GL_CXXALIAS_SYS (func, rettype, parameters);
206: except that the C function func may have a slightly different declaration.
207: A cast is used to silence the "invalid conversion" error that would
208: otherwise occur. */
209: #if defined __cplusplus && defined GNULIB_NAMESPACE
210: # define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \
211: namespace GNULIB_NAMESPACE \
212: { \
213: static const struct _gl_ ## func ## _wrapper \
214: { \
215: typedef rettype (*type) parameters; \
216: \
217: inline operator type () const \
218: { \
219: return reinterpret_cast<type>(::func); \
220: } \
221: } func = {}; \
222: } \
223: _GL_EXTERN_C int _gl_cxxalias_dummy
224: #else
225: # define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \
226: _GL_EXTERN_C int _gl_cxxalias_dummy
227: #endif
228:
229: /* _GL_CXXALIAS_SYS_CAST2 (func, rettype, parameters, rettype2, parameters2);
230: is like _GL_CXXALIAS_SYS (func, rettype, parameters);
231: except that the C function is picked among a set of overloaded functions,
232: namely the one with rettype2 and parameters2. Two consecutive casts
233: are used to silence the "cannot find a match" and "invalid conversion"
234: errors that would otherwise occur. */
235: #if defined __cplusplus && defined GNULIB_NAMESPACE
236: /* The outer cast must be a reinterpret_cast.
237: The inner cast: When the function is defined as a set of overloaded
238: functions, it works as a static_cast<>, choosing the designated variant.
239: When the function is defined as a single variant, it works as a
240: reinterpret_cast<>. The parenthesized cast syntax works both ways. */
241: # define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \
242: namespace GNULIB_NAMESPACE \
243: { \
244: static const struct _gl_ ## func ## _wrapper \
245: { \
246: typedef rettype (*type) parameters; \
247: \
248: inline operator type () const \
249: { \
250: return reinterpret_cast<type>((rettype2 (*) parameters2)(::func)); \
251: } \
252: } func = {}; \
253: } \
254: _GL_EXTERN_C int _gl_cxxalias_dummy
255: #else
256: # define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \
257: _GL_EXTERN_C int _gl_cxxalias_dummy
258: #endif
259:
260: /* _GL_CXXALIASWARN (func);
261: causes a warning to be emitted when ::func is used but not when
262: GNULIB_NAMESPACE::func is used. func must be defined without overloaded
263: variants. */
264: #if defined __cplusplus && defined GNULIB_NAMESPACE
265: # define _GL_CXXALIASWARN(func) \
266: _GL_CXXALIASWARN_1 (func, GNULIB_NAMESPACE)
267: # define _GL_CXXALIASWARN_1(func,namespace) \
268: _GL_CXXALIASWARN_2 (func, namespace)
269: /* To work around GCC bug <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
270: we enable the warning only when not optimizing. */
271: # if !__OPTIMIZE__
272: # define _GL_CXXALIASWARN_2(func,namespace) \
273: _GL_WARN_ON_USE (func, \
274: "The symbol ::" #func " refers to the system function. " \
275: "Use " #namespace "::" #func " instead.")
276: # elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
277: # define _GL_CXXALIASWARN_2(func,namespace) \
278: extern __typeof__ (func) func
279: # else
280: # define _GL_CXXALIASWARN_2(func,namespace) \
281: _GL_EXTERN_C int _gl_cxxalias_dummy
282: # endif
283: #else
284: # define _GL_CXXALIASWARN(func) \
285: _GL_EXTERN_C int _gl_cxxalias_dummy
286: #endif
287:
288: /* _GL_CXXALIASWARN1 (func, rettype, parameters_and_attributes);
289: causes a warning to be emitted when the given overloaded variant of ::func
290: is used but not when GNULIB_NAMESPACE::func is used. */
291: #if defined __cplusplus && defined GNULIB_NAMESPACE
292: # define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \
293: _GL_CXXALIASWARN1_1 (func, rettype, parameters_and_attributes, \
294: GNULIB_NAMESPACE)
295: # define _GL_CXXALIASWARN1_1(func,rettype,parameters_and_attributes,namespace) \
296: _GL_CXXALIASWARN1_2 (func, rettype, parameters_and_attributes, namespace)
297: /* To work around GCC bug <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
298: we enable the warning only when not optimizing. */
299: # if !__OPTIMIZE__
300: # define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
301: _GL_WARN_ON_USE_CXX (func, rettype, parameters_and_attributes, \
302: "The symbol ::" #func " refers to the system function. " \
303: "Use " #namespace "::" #func " instead.")
304: # elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
305: # define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
306: extern __typeof__ (func) func
307: # else
308: # define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
309: _GL_EXTERN_C int _gl_cxxalias_dummy
310: # endif
311: #else
312: # define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \
313: _GL_EXTERN_C int _gl_cxxalias_dummy
314: #endif
315:
316: #endif /* _GL_CXXDEFS_H */
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