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 #define MOZ_IS_GCC 0
  13
  14 #if !defined(__clang__) && defined(__GNUC__)
  15
  16 #  undef MOZ_IS_GCC
  17 #  define MOZ_IS_GCC 1
  18 /*
  19  * These macros should simplify gcc version checking. For example, to check
  20  * for gcc 4.7.1 or later, check `#if MOZ_GCC_VERSION_AT_LEAST(4, 7, 1)`.
  21  */
  22 #  define MOZ_GCC_VERSION_AT_LEAST(major, minor, patchlevel)            \
  23     ((__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) >= \
  24      ((major)*10000 + (minor)*100 + (patchlevel)))
  25 #  define MOZ_GCC_VERSION_AT_MOST(major, minor, patchlevel)             \
  26     ((__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) <= \
  27      ((major)*10000 + (minor)*100 + (patchlevel)))
  28 #  if !MOZ_GCC_VERSION_AT_LEAST(6, 1, 0)
  29 #    error "mfbt (and Gecko) require at least gcc 6.1 to build."
  30 #  endif
  31
  32 #endif
  33
  34 /*
  35  * The situation with standard libraries is a lot worse than with compilers,
  36  * particularly as clang and gcc could end up using one of three or so standard
  37  * libraries, and they may not be up-to-snuff with newer C++11 versions. To
  38  * detect the library, we're going to include cstddef (which is a small header
  39  * which will be transitively included by everybody else at some point) to grab
  40  * the version macros and deduce macros from there.
  41  */
  42 #ifdef __cplusplus
  43 #  include <cstddef>
  44 #  ifdef _STLPORT_MAJOR
  45 #    define MOZ_USING_STLPORT 1
  46 #    define MOZ_STLPORT_VERSION_AT_LEAST(major, minor, patch) \
  47       (_STLPORT_VERSION >= ((major) << 8 | (minor) << 4 | (patch)))
  48 #  elif defined(_LIBCPP_VERSION)
  49 /*
  50  * libc++, unfortunately, doesn't appear to have useful versioning macros.
  51  * Hopefully, the recommendations of N3694 with respect to standard libraries
  52  * will get applied instead and we won't need to worry about version numbers
  53  * here.
  54  */
  55 #    define MOZ_USING_LIBCXX 1
  56 #  elif defined(__GLIBCXX__)
  57 #    define MOZ_USING_LIBSTDCXX 1
  58 /*
  59  * libstdc++ is also annoying and doesn't give us useful versioning macros
  60  * for the library. If we're using gcc, then assume that libstdc++ matches
  61  * the compiler version. If we're using clang, we're going to have to fake
  62  * major/minor combinations by looking for newly-defined config macros.
  63  */
  64 #    if MOZ_IS_GCC
  65 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  66         MOZ_GCC_VERSION_AT_LEAST(major, minor, patch)
  67 #    elif defined(_GLIBCXX_THROW_OR_ABORT)
  68 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  69         ((major) < 4 || ((major) == 4 && (minor) <= 8))
  70 #    elif defined(_GLIBCXX_NOEXCEPT)
  71 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  72         ((major) < 4 || ((major) == 4 && (minor) <= 7))
  73 #    elif defined(_GLIBCXX_USE_DEPRECATED)
  74 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  75         ((major) < 4 || ((major) == 4 && (minor) <= 6))
  76 #    elif defined(_GLIBCXX_PSEUDO_VISIBILITY)
  77 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  78         ((major) < 4 || ((major) == 4 && (minor) <= 5))
  79 #    elif defined(_GLIBCXX_BEGIN_EXTERN_C)
  80 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  81         ((major) < 4 || ((major) == 4 && (minor) <= 4))
  82 #    elif defined(_GLIBCXX_VISIBILITY_ATTR)
  83 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  84         ((major) < 4 || ((major) == 4 && (minor) <= 3))
  85 #    elif defined(_GLIBCXX_VISIBILITY)
  86 #      define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) \
  87         ((major) < 4 || ((major) == 4 && (minor) <= 2))
  88 #    else
  89 #      error "Your version of libstdc++ is unknown to us and is likely too old."
  90 #    endif
  91 #  endif
  92
  93 // Flesh out the defines for everyone else
  94 #  ifndef MOZ_USING_STLPORT
  95 #    define MOZ_USING_STLPORT 0
  96 #    define MOZ_STLPORT_VERSION_AT_LEAST(major, minor, patch) 0
  97 #  endif
  98 #  ifndef MOZ_USING_LIBCXX
  99 #    define MOZ_USING_LIBCXX 0
 100 #  endif
 101 #  ifndef MOZ_USING_LIBSTDCXX
 102 #    define MOZ_USING_LIBSTDCXX 0
 103 #    define MOZ_LIBSTDCXX_VERSION_AT_LEAST(major, minor, patch) 0
 104 #  endif
 105 #endif /* __cplusplus */
 106
 107 #endif /* mozilla_Compiler_h */