| 1 | /* C++ compatible function declaration macros. |
| 2 | Copyright (C) 2010-2014 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 <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 */ |