dhcpd-pools  2.28
ISC dhcpd lease usage analyser
c++defs.h
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1 #ifndef _GL_CXXDEFS_H
2 #define _GL_CXXDEFS_H
3 
4 /* The three most frequent use cases of these macros are:
5 
6  * For providing a substitute for a function that is missing on some
7  platforms, but is declared and works fine on the platforms on which
8  it exists:
9 
10  #if @GNULIB_FOO@
11  # if !@HAVE_FOO@
12  _GL_FUNCDECL_SYS (foo, ...);
13  # endif
14  _GL_CXXALIAS_SYS (foo, ...);
15  _GL_CXXALIASWARN (foo);
16  #elif defined GNULIB_POSIXCHECK
17  ...
18  #endif
19 
20  * For providing a replacement for a function that exists on all platforms,
21  but is broken/insufficient and needs to be replaced on some platforms:
22 
23  #if @GNULIB_FOO@
24  # if @REPLACE_FOO@
25  # if !(defined __cplusplus && defined GNULIB_NAMESPACE)
26  # undef foo
27  # define foo rpl_foo
28  # endif
29  _GL_FUNCDECL_RPL (foo, ...);
30  _GL_CXXALIAS_RPL (foo, ...);
31  # else
32  _GL_CXXALIAS_SYS (foo, ...);
33  # endif
34  _GL_CXXALIASWARN (foo);
35  #elif defined GNULIB_POSIXCHECK
36  ...
37  #endif
38 
39  * For providing a replacement for a function that exists on some platforms
40  but is broken/insufficient and needs to be replaced on some of them and
41  is additionally either missing or undeclared on some other platforms:
42 
43  #if @GNULIB_FOO@
44  # if @REPLACE_FOO@
45  # if !(defined __cplusplus && defined GNULIB_NAMESPACE)
46  # undef foo
47  # define foo rpl_foo
48  # endif
49  _GL_FUNCDECL_RPL (foo, ...);
50  _GL_CXXALIAS_RPL (foo, ...);
51  # else
52  # if !@HAVE_FOO@ or if !@HAVE_DECL_FOO@
53  _GL_FUNCDECL_SYS (foo, ...);
54  # endif
55  _GL_CXXALIAS_SYS (foo, ...);
56  # endif
57  _GL_CXXALIASWARN (foo);
58  #elif defined GNULIB_POSIXCHECK
59  ...
60  #endif
61 */
62 
63 /* _GL_EXTERN_C declaration;
64  performs the declaration with C linkage. */
65 #if defined __cplusplus
66 # define _GL_EXTERN_C extern "C"
67 #else
68 # define _GL_EXTERN_C extern
69 #endif
70 
71 /* _GL_FUNCDECL_RPL (func, rettype, parameters_and_attributes);
72  declares a replacement function, named rpl_func, with the given prototype,
73  consisting of return type, parameters, and attributes.
74  Example:
75  _GL_FUNCDECL_RPL (open, int, (const char *filename, int flags, ...)
76  _GL_ARG_NONNULL ((1)));
77  */
78 #define _GL_FUNCDECL_RPL(func,rettype,parameters_and_attributes) \
79  _GL_FUNCDECL_RPL_1 (rpl_##func, rettype, parameters_and_attributes)
80 #define _GL_FUNCDECL_RPL_1(rpl_func,rettype,parameters_and_attributes) \
81  _GL_EXTERN_C rettype rpl_func parameters_and_attributes
82 
83 /* _GL_FUNCDECL_SYS (func, rettype, parameters_and_attributes);
84  declares the system function, named func, with the given prototype,
85  consisting of return type, parameters, and attributes.
86  Example:
87  _GL_FUNCDECL_SYS (open, int, (const char *filename, int flags, ...)
88  _GL_ARG_NONNULL ((1)));
89  */
90 #define _GL_FUNCDECL_SYS(func,rettype,parameters_and_attributes) \
91  _GL_EXTERN_C rettype func parameters_and_attributes
92 
93 /* _GL_CXXALIAS_RPL (func, rettype, parameters);
94  declares a C++ alias called GNULIB_NAMESPACE::func
95  that redirects to rpl_func, if GNULIB_NAMESPACE is defined.
96  Example:
97  _GL_CXXALIAS_RPL (open, int, (const char *filename, int flags, ...));
98  */
99 #define _GL_CXXALIAS_RPL(func,rettype,parameters) \
100  _GL_CXXALIAS_RPL_1 (func, rpl_##func, rettype, parameters)
101 #if defined __cplusplus && defined GNULIB_NAMESPACE
102 # define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \
103  namespace GNULIB_NAMESPACE \
104  { \
105  rettype (*const func) parameters = ::rpl_func; \
106  } \
107  _GL_EXTERN_C int _gl_cxxalias_dummy
108 #else
109 # define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \
110  _GL_EXTERN_C int _gl_cxxalias_dummy
111 #endif
112 
113 /* _GL_CXXALIAS_RPL_CAST_1 (func, rpl_func, rettype, parameters);
114  is like _GL_CXXALIAS_RPL_1 (func, rpl_func, rettype, parameters);
115  except that the C function rpl_func may have a slightly different
116  declaration. A cast is used to silence the "invalid conversion" error
117  that would otherwise occur. */
118 #if defined __cplusplus && defined GNULIB_NAMESPACE
119 # define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \
120  namespace GNULIB_NAMESPACE \
121  { \
122  rettype (*const func) parameters = \
123  reinterpret_cast<rettype(*)parameters>(::rpl_func); \
124  } \
125  _GL_EXTERN_C int _gl_cxxalias_dummy
126 #else
127 # define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \
128  _GL_EXTERN_C int _gl_cxxalias_dummy
129 #endif
130 
131 /* _GL_CXXALIAS_SYS (func, rettype, parameters);
132  declares a C++ alias called GNULIB_NAMESPACE::func
133  that redirects to the system provided function func, if GNULIB_NAMESPACE
134  is defined.
135  Example:
136  _GL_CXXALIAS_SYS (open, int, (const char *filename, int flags, ...));
137  */
138 #if defined __cplusplus && defined GNULIB_NAMESPACE
139  /* If we were to write
140  rettype (*const func) parameters = ::func;
141  like above in _GL_CXXALIAS_RPL_1, the compiler could optimize calls
142  better (remove an indirection through a 'static' pointer variable),
143  but then the _GL_CXXALIASWARN macro below would cause a warning not only
144  for uses of ::func but also for uses of GNULIB_NAMESPACE::func. */
145 # define _GL_CXXALIAS_SYS(func,rettype,parameters) \
146  namespace GNULIB_NAMESPACE \
147  { \
148  static rettype (*func) parameters = ::func; \
149  } \
150  _GL_EXTERN_C int _gl_cxxalias_dummy
151 #else
152 # define _GL_CXXALIAS_SYS(func,rettype,parameters) \
153  _GL_EXTERN_C int _gl_cxxalias_dummy
154 #endif
155 
156 /* _GL_CXXALIAS_SYS_CAST (func, rettype, parameters);
157  is like _GL_CXXALIAS_SYS (func, rettype, parameters);
158  except that the C function func may have a slightly different declaration.
159  A cast is used to silence the "invalid conversion" error that would
160  otherwise occur. */
161 #if defined __cplusplus && defined GNULIB_NAMESPACE
162 # define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \
163  namespace GNULIB_NAMESPACE \
164  { \
165  static rettype (*func) parameters = \
166  reinterpret_cast<rettype(*)parameters>(::func); \
167  } \
168  _GL_EXTERN_C int _gl_cxxalias_dummy
169 #else
170 # define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \
171  _GL_EXTERN_C int _gl_cxxalias_dummy
172 #endif
173 
174 /* _GL_CXXALIAS_SYS_CAST2 (func, rettype, parameters, rettype2, parameters2);
175  is like _GL_CXXALIAS_SYS (func, rettype, parameters);
176  except that the C function is picked among a set of overloaded functions,
177  namely the one with rettype2 and parameters2. Two consecutive casts
178  are used to silence the "cannot find a match" and "invalid conversion"
179  errors that would otherwise occur. */
180 #if defined __cplusplus && defined GNULIB_NAMESPACE
181  /* The outer cast must be a reinterpret_cast.
182  The inner cast: When the function is defined as a set of overloaded
183  functions, it works as a static_cast<>, choosing the designated variant.
184  When the function is defined as a single variant, it works as a
185  reinterpret_cast<>. The parenthesized cast syntax works both ways. */
186 # define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \
187  namespace GNULIB_NAMESPACE \
188  { \
189  static rettype (*func) parameters = \
190  reinterpret_cast<rettype(*)parameters>( \
191  (rettype2(*)parameters2)(::func)); \
192  } \
193  _GL_EXTERN_C int _gl_cxxalias_dummy
194 #else
195 # define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \
196  _GL_EXTERN_C int _gl_cxxalias_dummy
197 #endif
198 
199 /* _GL_CXXALIASWARN (func);
200  causes a warning to be emitted when ::func is used but not when
201  GNULIB_NAMESPACE::func is used. func must be defined without overloaded
202  variants. */
203 #if defined __cplusplus && defined GNULIB_NAMESPACE
204 # define _GL_CXXALIASWARN(func) \
205  _GL_CXXALIASWARN_1 (func, GNULIB_NAMESPACE)
206 # define _GL_CXXALIASWARN_1(func,namespace) \
207  _GL_CXXALIASWARN_2 (func, namespace)
208 /* To work around GCC bug <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
209  we enable the warning only when not optimizing. */
210 # if !__OPTIMIZE__
211 # define _GL_CXXALIASWARN_2(func,namespace) \
212  _GL_WARN_ON_USE (func, \
213  "The symbol ::" #func " refers to the system function. " \
214  "Use " #namespace "::" #func " instead.")
215 # elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
216 # define _GL_CXXALIASWARN_2(func,namespace) \
217  extern __typeof__ (func) func
218 # else
219 # define _GL_CXXALIASWARN_2(func,namespace) \
220  _GL_EXTERN_C int _gl_cxxalias_dummy
221 # endif
222 #else
223 # define _GL_CXXALIASWARN(func) \
224  _GL_EXTERN_C int _gl_cxxalias_dummy
225 #endif
226 
227 /* _GL_CXXALIASWARN1 (func, rettype, parameters_and_attributes);
228  causes a warning to be emitted when the given overloaded variant of ::func
229  is used but not when GNULIB_NAMESPACE::func is used. */
230 #if defined __cplusplus && defined GNULIB_NAMESPACE
231 # define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \
232  _GL_CXXALIASWARN1_1 (func, rettype, parameters_and_attributes, \
233  GNULIB_NAMESPACE)
234 # define _GL_CXXALIASWARN1_1(func,rettype,parameters_and_attributes,namespace) \
235  _GL_CXXALIASWARN1_2 (func, rettype, parameters_and_attributes, namespace)
236 /* To work around GCC bug <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
237  we enable the warning only when not optimizing. */
238 # if !__OPTIMIZE__
239 # define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
240  _GL_WARN_ON_USE_CXX (func, rettype, parameters_and_attributes, \
241  "The symbol ::" #func " refers to the system function. " \
242  "Use " #namespace "::" #func " instead.")
243 # elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
244 # define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
245  extern __typeof__ (func) func
246 # else
247 # define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
248  _GL_EXTERN_C int _gl_cxxalias_dummy
249 # endif
250 #else
251 # define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \
252  _GL_EXTERN_C int _gl_cxxalias_dummy
253 #endif
254 
255 #endif /* _GL_CXXDEFS_H */