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1 /* C++ compatible function declaration macros. | |
2 Copyright (C) 2010, 2011 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 Lesser 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 <http://www.gnu.org/licenses/>. */ | |
16 | |
17 #ifndef _GL_CXXDEFS_H | |
18 #define _GL_CXXDEFS_H | |
19 | |
20 /* The three most frequent use cases of these macros are: | |
21 | |
22 * For providing a substitute for a function that is missing on some | |
23 platforms, but is declared and works fine on the platforms on which | |
24 it exists: | |
25 | |
26 #if @GNULIB_FOO@ | |
27 # if !@HAVE_FOO@ | |
28 _GL_FUNCDECL_SYS (foo, ...); | |
29 # endif | |
30 _GL_CXXALIAS_SYS (foo, ...); | |
31 _GL_CXXALIASWARN (foo); | |
32 #elif defined GNULIB_POSIXCHECK | |
33 ... | |
34 #endif | |
35 | |
36 * For providing a replacement for a function that exists on all platforms, | |
37 but is broken/insufficient and needs to be replaced on some platforms: | |
38 | |
39 #if @GNULIB_FOO@ | |
40 # if @REPLACE_FOO@ | |
41 # if !(defined __cplusplus && defined GNULIB_NAMESPACE) | |
42 # undef foo | |
43 # define foo rpl_foo | |
44 # endif | |
45 _GL_FUNCDECL_RPL (foo, ...); | |
46 _GL_CXXALIAS_RPL (foo, ...); | |
47 # else | |
48 _GL_CXXALIAS_SYS (foo, ...); | |
49 # endif | |
50 _GL_CXXALIASWARN (foo); | |
51 #elif defined GNULIB_POSIXCHECK | |
52 ... | |
53 #endif | |
54 | |
55 * For providing a replacement for a function that exists on some platforms | |
56 but is broken/insufficient and needs to be replaced on some of them and | |
57 is additionally either missing or undeclared on some other platforms: | |
58 | |
59 #if @GNULIB_FOO@ | |
60 # if @REPLACE_FOO@ | |
61 # if !(defined __cplusplus && defined GNULIB_NAMESPACE) | |
62 # undef foo | |
63 # define foo rpl_foo | |
64 # endif | |
65 _GL_FUNCDECL_RPL (foo, ...); | |
66 _GL_CXXALIAS_RPL (foo, ...); | |
67 # else | |
68 # if !@HAVE_FOO@ or if !@HAVE_DECL_FOO@ | |
69 _GL_FUNCDECL_SYS (foo, ...); | |
70 # endif | |
71 _GL_CXXALIAS_SYS (foo, ...); | |
72 # endif | |
73 _GL_CXXALIASWARN (foo); | |
74 #elif defined GNULIB_POSIXCHECK | |
75 ... | |
76 #endif | |
77 */ | |
78 | |
79 /* _GL_EXTERN_C declaration; | |
80 performs the declaration with C linkage. */ | |
81 #if defined __cplusplus | |
82 # define _GL_EXTERN_C extern "C" | |
83 #else | |
84 # define _GL_EXTERN_C extern | |
85 #endif | |
86 | |
87 /* _GL_FUNCDECL_RPL (func, rettype, parameters_and_attributes); | |
88 declares a replacement function, named rpl_func, with the given prototype, | |
89 consisting of return type, parameters, and attributes. | |
90 Example: | |
91 _GL_FUNCDECL_RPL (open, int, (const char *filename, int flags, ...) | |
92 _GL_ARG_NONNULL ((1))); | |
93 */ | |
94 #define _GL_FUNCDECL_RPL(func,rettype,parameters_and_attributes) \ | |
95 _GL_FUNCDECL_RPL_1 (rpl_##func, rettype, parameters_and_attributes) | |
96 #define _GL_FUNCDECL_RPL_1(rpl_func,rettype,parameters_and_attributes) \ | |
97 _GL_EXTERN_C rettype rpl_func parameters_and_attributes | |
98 | |
99 /* _GL_FUNCDECL_SYS (func, rettype, parameters_and_attributes); | |
100 declares the system function, named func, with the given prototype, | |
101 consisting of return type, parameters, and attributes. | |
102 Example: | |
103 _GL_FUNCDECL_SYS (open, int, (const char *filename, int flags, ...) | |
104 _GL_ARG_NONNULL ((1))); | |
105 */ | |
106 #define _GL_FUNCDECL_SYS(func,rettype,parameters_and_attributes) \ | |
107 _GL_EXTERN_C rettype func parameters_and_attributes | |
108 | |
109 /* _GL_CXXALIAS_RPL (func, rettype, parameters); | |
110 declares a C++ alias called GNULIB_NAMESPACE::func | |
111 that redirects to rpl_func, if GNULIB_NAMESPACE is defined. | |
112 Example: | |
113 _GL_CXXALIAS_RPL (open, int, (const char *filename, int flags, ...)); | |
114 */ | |
115 #define _GL_CXXALIAS_RPL(func,rettype,parameters) \ | |
116 _GL_CXXALIAS_RPL_1 (func, rpl_##func, rettype, parameters) | |
117 #if defined __cplusplus && defined GNULIB_NAMESPACE | |
118 # define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \ | |
119 namespace GNULIB_NAMESPACE \ | |
120 { \ | |
121 rettype (*const func) parameters = ::rpl_func; \ | |
122 } \ | |
123 _GL_EXTERN_C int _gl_cxxalias_dummy | |
124 #else | |
125 # define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \ | |
126 _GL_EXTERN_C int _gl_cxxalias_dummy | |
127 #endif | |
128 | |
129 /* _GL_CXXALIAS_RPL_CAST_1 (func, rpl_func, rettype, parameters); | |
130 is like _GL_CXXALIAS_RPL_1 (func, rpl_func, rettype, parameters); | |
131 except that the C function rpl_func may have a slightly different | |
132 declaration. A cast is used to silence the "invalid conversion" error | |
133 that would otherwise occur. */ | |
134 #if defined __cplusplus && defined GNULIB_NAMESPACE | |
135 # define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \ | |
136 namespace GNULIB_NAMESPACE \ | |
137 { \ | |
138 rettype (*const func) parameters = \ | |
139 reinterpret_cast<rettype(*)parameters>(::rpl_func); \ | |
140 } \ | |
141 _GL_EXTERN_C int _gl_cxxalias_dummy | |
142 #else | |
143 # define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \ | |
144 _GL_EXTERN_C int _gl_cxxalias_dummy | |
145 #endif | |
146 | |
147 /* _GL_CXXALIAS_SYS (func, rettype, parameters); | |
148 declares a C++ alias called GNULIB_NAMESPACE::func | |
149 that redirects to the system provided function func, if GNULIB_NAMESPACE | |
150 is defined. | |
151 Example: | |
152 _GL_CXXALIAS_SYS (open, int, (const char *filename, int flags, ...)); | |
153 */ | |
154 #if defined __cplusplus && defined GNULIB_NAMESPACE | |
155 /* If we were to write | |
156 rettype (*const func) parameters = ::func; | |
157 like above in _GL_CXXALIAS_RPL_1, the compiler could optimize calls | |
158 better (remove an indirection through a 'static' pointer variable), | |
159 but then the _GL_CXXALIASWARN macro below would cause a warning not only | |
160 for uses of ::func but also for uses of GNULIB_NAMESPACE::func. */ | |
161 # define _GL_CXXALIAS_SYS(func,rettype,parameters) \ | |
162 namespace GNULIB_NAMESPACE \ | |
163 { \ | |
164 static rettype (*func) parameters = ::func; \ | |
165 } \ | |
166 _GL_EXTERN_C int _gl_cxxalias_dummy | |
167 #else | |
168 # define _GL_CXXALIAS_SYS(func,rettype,parameters) \ | |
169 _GL_EXTERN_C int _gl_cxxalias_dummy | |
170 #endif | |
171 | |
172 /* _GL_CXXALIAS_SYS_CAST (func, rettype, parameters); | |
173 is like _GL_CXXALIAS_SYS (func, rettype, parameters); | |
174 except that the C function func may have a slightly different declaration. | |
175 A cast is used to silence the "invalid conversion" error that would | |
176 otherwise occur. */ | |
177 #if defined __cplusplus && defined GNULIB_NAMESPACE | |
178 # define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \ | |
179 namespace GNULIB_NAMESPACE \ | |
180 { \ | |
181 static rettype (*func) parameters = \ | |
182 reinterpret_cast<rettype(*)parameters>(::func); \ | |
183 } \ | |
184 _GL_EXTERN_C int _gl_cxxalias_dummy | |
185 #else | |
186 # define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \ | |
187 _GL_EXTERN_C int _gl_cxxalias_dummy | |
188 #endif | |
189 | |
190 /* _GL_CXXALIAS_SYS_CAST2 (func, rettype, parameters, rettype2, parameters2); | |
191 is like _GL_CXXALIAS_SYS (func, rettype, parameters); | |
192 except that the C function is picked among a set of overloaded functions, | |
193 namely the one with rettype2 and parameters2. Two consecutive casts | |
194 are used to silence the "cannot find a match" and "invalid conversion" | |
195 errors that would otherwise occur. */ | |
196 #if defined __cplusplus && defined GNULIB_NAMESPACE | |
197 /* The outer cast must be a reinterpret_cast. | |
198 The inner cast: When the function is defined as a set of overloaded | |
199 functions, it works as a static_cast<>, choosing the designated variant. | |
200 When the function is defined as a single variant, it works as a | |
201 reinterpret_cast<>. The parenthesized cast syntax works both ways. */ | |
202 # define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \ | |
203 namespace GNULIB_NAMESPACE \ | |
204 { \ | |
205 static rettype (*func) parameters = \ | |
206 reinterpret_cast<rettype(*)parameters>( \ | |
207 (rettype2(*)parameters2)(::func)); \ | |
208 } \ | |
209 _GL_EXTERN_C int _gl_cxxalias_dummy | |
210 #else | |
211 # define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \ | |
212 _GL_EXTERN_C int _gl_cxxalias_dummy | |
213 #endif | |
214 | |
215 /* _GL_CXXALIASWARN (func); | |
216 causes a warning to be emitted when ::func is used but not when | |
217 GNULIB_NAMESPACE::func is used. func must be defined without overloaded | |
218 variants. */ | |
219 #if defined __cplusplus && defined GNULIB_NAMESPACE | |
220 # define _GL_CXXALIASWARN(func) \ | |
221 _GL_CXXALIASWARN_1 (func, GNULIB_NAMESPACE) | |
222 # define _GL_CXXALIASWARN_1(func,namespace) \ | |
223 _GL_CXXALIASWARN_2 (func, namespace) | |
224 /* To work around GCC bug <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>, | |
225 we enable the warning only when not optimizing. */ | |
226 # if !__OPTIMIZE__ | |
227 # define _GL_CXXALIASWARN_2(func,namespace) \ | |
228 _GL_WARN_ON_USE (func, \ | |
229 "The symbol ::" #func " refers to the system function. " \ | |
230 "Use " #namespace "::" #func " instead.") | |
231 # elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING | |
232 # define _GL_CXXALIASWARN_2(func,namespace) \ | |
233 extern __typeof__ (func) func | |
234 # else | |
235 # define _GL_CXXALIASWARN_2(func,namespace) \ | |
236 _GL_EXTERN_C int _gl_cxxalias_dummy | |
237 # endif | |
238 #else | |
239 # define _GL_CXXALIASWARN(func) \ | |
240 _GL_EXTERN_C int _gl_cxxalias_dummy | |
241 #endif | |
242 | |
243 /* _GL_CXXALIASWARN1 (func, rettype, parameters_and_attributes); | |
244 causes a warning to be emitted when the given overloaded variant of ::func | |
245 is used but not when GNULIB_NAMESPACE::func is used. */ | |
246 #if defined __cplusplus && defined GNULIB_NAMESPACE | |
247 # define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \ | |
248 _GL_CXXALIASWARN1_1 (func, rettype, parameters_and_attributes, \ | |
249 GNULIB_NAMESPACE) | |
250 # define _GL_CXXALIASWARN1_1(func,rettype,parameters_and_attributes,namespace) \ | |
251 _GL_CXXALIASWARN1_2 (func, rettype, parameters_and_attributes, namespace) | |
252 /* To work around GCC bug <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>, | |
253 we enable the warning only when not optimizing. */ | |
254 # if !__OPTIMIZE__ | |
255 # define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace)
\ | |
256 _GL_WARN_ON_USE_CXX (func, rettype, parameters_and_attributes, \ | |
257 "The symbol ::" #func " refers to the system function.
" \ | |
258 "Use " #namespace "::" #func " instead.") | |
259 # elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING | |
260 # define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace)
\ | |
261 extern __typeof__ (func) func | |
262 # else | |
263 # define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace)
\ | |
264 _GL_EXTERN_C int _gl_cxxalias_dummy | |
265 # endif | |
266 #else | |
267 # define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \ | |
268 _GL_EXTERN_C int _gl_cxxalias_dummy | |
269 #endif | |
270 | |
271 #endif /* _GL_CXXDEFS_H */ | |
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