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f434ba03 | 1 | /* C++ compatible function declaration macros. |
49e4877c | 2 | Copyright (C) 2010-2016 Free Software Foundation, Inc. |
f434ba03 PA |
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 | |
770d76d7 | 12 | General Public License for more details. |
f434ba03 PA |
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 */ |