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