libdap Updated for version 3.21.1
libdap4 is an implementation of OPeNDAP's DAP protocol.
c++defs.h
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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 */