mdw@git.distorted.org.uk Git - mLib/blob - utils/macros.h

   1 /* -*-c-*-
   2  *
   3  * Handy macros
   4  *
   5  * (c) 2003 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of the mLib utilities library.
  11  *
  12  * mLib is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU Library General Public License as
  14  * published by the Free Software Foundation; either version 2 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * mLib is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU Library General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Library General Public
  23  * License along with mLib; if not, write to the Free
  24  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  25  * MA 02111-1307, USA.
  26  */
  27
  28 #ifndef MLIB_MACROS_H
  29 #define MLIB_MACROS_H
  30
  31 #ifdef __cplusplus
  32   extern "C" {
  33 #endif
  34
  35 /*----- Miscellaneous utility macros --------------------------------------*/
  36
  37 #define N(v) (sizeof(v)/sizeof(*v))
  38
  39 #define MLIB__STR(x) #x
  40 #define STR(x) MLIB__STR(x)
  41
  42 #define MLIB__GLUE(x, y) x##y
  43 #define GLUE(x, y) MLIB__GLUE(x, y)
  44
  45 /*----- Compiler diagnostics ----------------------------------------------*/
  46
  47 /* --- Compiler-specific definitions --- */
  48
  49 #if defined(__GNUC__)
  50 #  define GCC_VERSION_P(maj, min)                                       \
  51         (__GNUC__ > (maj) || (__GNUC__ == (maj) && __GNUC_MINOR__ >= (min)))
  52 #else
  53 #  define GCC_VERSION_P(maj, min) 0
  54 #endif
  55
  56 #ifdef __clang__
  57 #  define CLANG_VERSION_P(maj, min)                                     \
  58         (__clang_major__ > (maj) || (__clang_major__ == (maj) &&        \
  59                                      __clang_minor__ >= (min)))
  60 #else
  61 #  define CLANG_VERSION_P(maj, min) 0
  62 #endif
  63
  64 #if GCC_VERSION_P(2, 5) || CLANG_VERSION_P(3, 3)
  65 #  define NORETURN __attribute__((noreturn))
  66 #  define PRINTF_LIKE(fix, aix) __attribute__((format(printf, fix, aix)))
  67 #  define SCANF_LIKE(fix, aix) __attribute__((format(scanf, fix, aix)))
  68 #  define IGNORABLE __attribute__((unused))
  69 #endif
  70
  71 #if GCC_VERSION_P(4, 5) || CLANG_VERSION_P(3, 3)
  72 #  define DEPRECATED(msg) __attribute__((deprecated(msg)))
  73 #elif GCC_VERSION_P(3, 1)
  74 #  define DEPRECATED(msg) __attribute__((deprecated))
  75 #endif
  76
  77 #if GCC_VERSION_P(4, 0) || CLANG_VERSION_P(3, 3)
  78 #  define EXECL_LIKE(ntrail) __attribute__((sentinel(ntrail)))
  79 #endif
  80
  81 #if CLANG_VERSION_P(3, 3)
  82
  83 #  define MLIB__PRAGMA_HACK(x) _Pragma(#x)
  84 #  define MLIB__MUFFLE_WARNINGS(warns, body)                            \
  85         _Pragma("clang diagnostic push")                                \
  86         warns                                                           \
  87         body                                                            \
  88         _Pragma("clang diagnostic pop")
  89 #  define CLANG_WARNING(warn)                                           \
  90         MLIB__PRAGMA_HACK(clang diagnostic ignored warn)
  91 #  define MUFFLE_WARNINGS_DECL(warns, body)                             \
  92         MLIB__MUFFLE_WARNINGS(warns, body)
  93 #  define MUFFLE_WARNINGS_EXPR(warns, body)                             \
  94         __extension__ ({ MLIB__MUFFLE_WARNINGS(warns, (body);) })
  95 #  define MUFFLE_WARNINGS_STMT(warns, body)                             \
  96         do { MLIB__MUFFLE_WARNINGS(warns, body) } while (0)
  97
  98 #elif GCC_VERSION_P(4, 6)
  99
 100    /* --- Diagnostic suppression in GCC: a tale of woe --- *
 101     *
 102     * This is extremely unpleasant, largely as a result of bugs in the GCC
 103     * preprocessor's handling of @_Pragma@.  The fundamental problem is
 104     * that it's the preprocessor, and not the compiler proper, which
 105     * detects @_Pragma@, emitting @#pragma@ lines into its output; and it
 106     * does it during macro expansion, even if the macro is being expanded
 107     * during argument collection.  Since arguments are expanded before
 108     * replacing the macro's invocation with its body, a pragma in an
 109     * argument will be emitted %%\emph{before}%% any pragmata in the body,
 110     * even if they appear before the argument in the body -- and even if
 111     * the argument doesn't actually appear anywhere at all in the body.
 112     *
 113     * Another, rather less significant, problem is that @_Pragma@'s
 114     * argument is a single string literal, recognized in translation phase
 115     * 4, before string-literal concatenation in phase 6, so we must build
 116     * pragma bodies as token lists and then stringify them.
 117     *
 118     * As a result, we need some subterfuge here.  The @MLIB__PRAGMA_HACK@
 119     * macro issues a @_Pragma@ on its argument token list, which it
 120     * stringifies; this deals with the second problem.  The first is
 121     * trickier: we must delay expansion of @MLIB__PRAGMA_HACK@ from the
 122     * argument collection phase to the body rescanning phase, and we do
 123     * this by splitting the invocations between @GCC_WARNING@ macro calls:
 124     * the name is left hanging from the previous call (or from
 125     * @MLIB__MUFFLE_WARNINGS@, in the first case) and the body is supplied
 126     * by @GCC_WARNING@, which also supplies the next @MLIB__PRAGMA_HACK@.
 127     * The remaining problem is to make sure we can dispose of the final
 128     * trailing @MLIB__PRAGMA_HACK@ harmlessly, which we do by introducing
 129     * an extra argument @emitp@, which may be either @t@ or @nil@; this
 130     * dispatches to an appropriate helper macro by means of token-pasting.
 131     *
 132     * I'm so sorry.
 133     */
 134
 135 #  define MLIB__PRAGMA_HACK_t(x) _Pragma(#x)
 136 #  define MLIB__PRAGMA_HACK_nil(x)
 137 #  define MLIB__PRAGMA_HACK(emitp, x) MLIB__PRAGMA_HACK_##emitp(x)
 138 #  define MLIB__MUFFLE_WARNINGS(warns, body)                            \
 139         _Pragma("GCC diagnostic push") MLIB__PRAGMA_HACK                \
 140         warns                                                           \
 141         (nil, nil)                                                      \
 142         body                                                            \
 143         _Pragma("GCC diagnostic pop")
 144 #  define GCC_WARNING(warn)                                             \
 145         (t, GCC diagnostic ignored warn) MLIB__PRAGMA_HACK
 146 #  define MUFFLE_WARNINGS_DECL(warns, body)                             \
 147         MLIB__MUFFLE_WARNINGS(warns, body)
 148 #  define MUFFLE_WARNINGS_EXPR(warns, body)                             \
 149         __extension__ ({ MLIB__MUFFLE_WARNINGS(warns, (body);) })
 150 #  define MUFFLE_WARNINGS_STMT(warns, body)                             \
 151         do { MLIB__MUFFLE_WARNINGS(warns, body) } while (0)
 152 #endif
 153
 154 /* --- Fallback definitions, mostly trivial --- */
 155
 156 #ifndef DEPRECATED
 157 #  define DEPRECATED(msg)
 158 #endif
 159
 160 #ifndef EXECL_LIKE
 161 #  define EXECL_LIKE(ntrail)
 162 #endif
 163
 164 #ifndef DISCARD
 165 #  define DISCARD(x) do if (x); while (0)
 166 #endif
 167
 168 #ifndef IGNORE
 169 #  define IGNORE(x) ((void)(x))
 170 #endif
 171
 172 #ifndef MUFFLE_WARNINGS_DECL
 173 #  define MUFFLE_WARNINGS_DECL(warns, body) body
 174 #endif
 175
 176 #ifndef MUFFLE_WARNINGS_EXPR
 177 #  define MUFFLE_WARNINGS_EXPR(warns, body) (body)
 178 #endif
 179
 180 #ifndef MUFFLE_WARNINGS_STMT
 181 #  define MUFFLE_WARNINGS_STMT(warns, body) do { body } while (0)
 182 #endif
 183
 184 #ifndef PRINTF_LIKE
 185 #  define PRINF_LIKE(fmtix, argix)
 186 #endif
 187
 188 #ifndef SCANF_LIKE
 189 #  define SCANF_LIKE(fmtix, argix)
 190 #endif
 191
 192 #ifndef IGNORABLE
 193 #  define IGNORABLE
 194 #endif
 195
 196 #ifndef GCC_WARNING
 197 #  define GCC_WARNING(warn)
 198 #endif
 199
 200 #ifndef CLANG_WARNING
 201 #  define CLANG_WARNING(warn)
 202 #endif
 203
 204 /*----- That's all, folks -------------------------------------------------*/
 205
 206 #ifdef __cplusplus
 207   }
 208 #endif
 209
 210 #endif