mfbt/Compiler.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /* Various compiler checks. */
   8
   9 #ifndef mozilla_Compiler_h
  10 #define mozilla_Compiler_h
  11
  12 #if !defined(__clang__) && defined(__GNUC__)
  13
  14 #define MOZ_IS_GCC 1
  15    /*
  16     * This macro should simplify gcc version checking. For example, to check
  17     * for gcc 4.5.1 or later, check `#ifdef MOZ_GCC_VERSION_AT_LEAST(4, 5, 1)`.
  18     */
  19 #  define MOZ_GCC_VERSION_AT_LEAST(major, minor, patchlevel)          \
  20      ((__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) \
  21       >= ((major) * 10000 + (minor) * 100 + (patchlevel)))
  22 #if !MOZ_GCC_VERSION_AT_LEAST(4, 4, 0)
  23 #  error "mfbt (and Gecko) require at least gcc 4.4 to build."
  24 #endif
  25
  26 #else
  27
  28 #define MOZ_IS_GCC 0
  29
  30 #endif
  31
  32 /*
  33  * The situation with standard libraries is a lot worse than with compilers,
  34  * particularly as clang and gcc could end up using one of three or so standard
  35  * libraries, and they may not be up-to-snuff with newer C++11 versions. To
  36  * detect the library, we're going to include cstddef (which is a small header
  37  * which will be transitively included by everybody else at some point) to grab
  38  * the version macros and deduce macros from there.
  39  */
  40 #ifdef __cplusplus
  41 #  include <cstddef>
  42 #  ifdef _STLPORT_MAJOR
  43 #    define MOZ_USING_STLPORT 1
  44 #    define MOZ_STLPORT_VERSION_AT_LEAST(major, minor, patch) \
  45        (_STLPORT_VERSION >= ((major) << 8 | (minor) << 4 | (patch)))
  46 #  elif defined(_LIBCPP_VERSION)
  47    /*
  48     * libc++, unfortunately, doesn't appear to have useful versioning macros.
  49     * Hopefully, the recommendations of N3694 with respect to standard libraries
  50     * will get applied instead and we won't need to worry about version numbers
  51     * here.
  52     */
  53 #    define MOZ_USING_LIBCXX 1
  54 #  elif defined(__GLIBCXX__)
  55 #    define MOZ_USING_LIBSTDCXX 1
  56    /*
  57     * libstdc++ is also annoying and doesn't give us useful versioning macros
  58     * for the library. If we're using gcc, then assume that libstdc++ matches
  59     * the compiler version. If we're using clang, we're going to have to fake
  60     * major/minor combinations by looking for newly-defined config macros.
  61     */
  62 #    if MOZ_IS_GCC
  63 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  64           MOZ_GCC_VERSION_AT_LEAST(major, minor, patch)
  65 #    elif defined(_GLIBCXX_THROW_OR_ABORT)
  66 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  67           ((major) < 4 || ((major) == 4 && (minor) <= 8))
  68 #    elif defined(_GLIBCXX_NOEXCEPT)
  69 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  70           ((major) < 4 || ((major) == 4 && (minor) <= 7))
  71 #    elif defined(_GLIBCXX_USE_DEPRECATED)
  72 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  73           ((major) < 4 || ((major) == 4 && (minor) <= 6))
  74 #    elif defined(_GLIBCXX_PSEUDO_VISIBILITY)
  75 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  76           ((major) < 4 || ((major) == 4 && (minor) <= 5))
  77 #    elif defined(_GLIBCXX_BEGIN_EXTERN_C)
  78 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  79           ((major) < 4 || ((major) == 4 && (minor) <= 4))
  80 #    elif defined(_GLIBCXX_VISIBILITY_ATTR)
  81 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  82           ((major) < 4 || ((major) == 4 && (minor) <= 3))
  83 #    elif defined(_GLIBCXX_VISIBILITY)
  84 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  85           ((major) < 4 || ((major) == 4 && (minor) <= 2))
  86 #    else
  87 #      error "Your version of libstdc++ is unknown to us and is likely too old."
  88 #    endif
  89 #  endif
  90
  91    // Flesh out the defines for everyone else
  92 #  ifndef MOZ_USING_STLPORT
  93 #    define MOZ_USING_STLPORT 0
  94 #    define MOZ_STLPORT_VERSION_AT_LEAST(major, minor, patch) 0
  95 #  endif
  96 #  ifndef MOZ_USING_LIBCXX
  97 #    define MOZ_USING_LIBCXX 0
  98 #  endif
  99 #  ifndef MOZ_USING_LIBSTDCXX
 100 #    define MOZ_USING_LIBSTDCXX 0
 101 #    define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) 0
 102 #  endif
 103 #endif /* __cplusplus */
 104
 105 #endif /* mozilla_Compiler_h */