base/compiler_specific.h

   1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_COMPILER_SPECIFIC_H_
   6 #define BASE_COMPILER_SPECIFIC_H_
   7
   8 #include "build/build_config.h"
   9
  10 #if defined(COMPILER_MSVC)
  11
  12 // Macros for suppressing and disabling warnings on MSVC.
  13 //
  14 // Warning numbers are enumerated at:
  15 // http://msdn.microsoft.com/en-us/library/8x5x43k7(VS.80).aspx
  16 //
  17 // The warning pragma:
  18 // http://msdn.microsoft.com/en-us/library/2c8f766e(VS.80).aspx
  19 //
  20 // Using __pragma instead of #pragma inside macros:
  21 // http://msdn.microsoft.com/en-us/library/d9x1s805.aspx
  22
  23 // MSVC_SUPPRESS_WARNING disables warning |n| for the remainder of the line and
  24 // for the next line of the source file.
  25 #define MSVC_SUPPRESS_WARNING(n) __pragma(warning(suppress:n))
  26
  27 // MSVC_PUSH_DISABLE_WARNING pushes |n| onto a stack of warnings to be disabled.
  28 // The warning remains disabled until popped by MSVC_POP_WARNING.
  29 #define MSVC_PUSH_DISABLE_WARNING(n) __pragma(warning(push)) \
  30                                      __pragma(warning(disable:n))
  31
  32 // MSVC_PUSH_WARNING_LEVEL pushes |n| as the global warning level.  The level
  33 // remains in effect until popped by MSVC_POP_WARNING().  Use 0 to disable all
  34 // warnings.
  35 #define MSVC_PUSH_WARNING_LEVEL(n) __pragma(warning(push, n))
  36
  37 // Pop effects of innermost MSVC_PUSH_* macro.
  38 #define MSVC_POP_WARNING() __pragma(warning(pop))
  39
  40 #define MSVC_DISABLE_OPTIMIZE() __pragma(optimize("", off))
  41 #define MSVC_ENABLE_OPTIMIZE() __pragma(optimize("", on))
  42
  43 // Allows |this| to be passed as an argument in constructor initializer lists.
  44 // This uses push/pop instead of the seemingly simpler suppress feature to avoid
  45 // having the warning be disabled for more than just |code|.
  46 //
  47 // Example usage:
  48 // Foo::Foo() : x(NULL), ALLOW_THIS_IN_INITIALIZER_LIST(y(this)), z(3) {}
  49 //
  50 // Compiler warning C4355: 'this': used in base member initializer list:
  51 // http://msdn.microsoft.com/en-us/library/3c594ae3(VS.80).aspx
  52 #define ALLOW_THIS_IN_INITIALIZER_LIST(code) MSVC_PUSH_DISABLE_WARNING(4355) \
  53                                              code \
  54                                              MSVC_POP_WARNING()
  55
  56 #else  // Not MSVC
  57
  58 #define MSVC_SUPPRESS_WARNING(n)
  59 #define MSVC_PUSH_DISABLE_WARNING(n)
  60 #define MSVC_PUSH_WARNING_LEVEL(n)
  61 #define MSVC_POP_WARNING()
  62 #define MSVC_DISABLE_OPTIMIZE()
  63 #define MSVC_ENABLE_OPTIMIZE()
  64 #define ALLOW_THIS_IN_INITIALIZER_LIST(code) code
  65
  66 #endif  // COMPILER_MSVC
  67
  68
  69 #if defined(COMPILER_GCC)
  70
  71 #define ALLOW_UNUSED __attribute__((unused))
  72 #define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
  73
  74 // Tell the compiler a function is using a printf-style format string.
  75 // |format_param| is the one-based index of the format string parameter;
  76 // |dots_param| is the one-based index of the "..." parameter.
  77 // For v*printf functions (which take a va_list), pass 0 for dots_param.
  78 // (This is undocumented but matches what the system C headers do.)
  79 #define PRINTF_FORMAT(format_param, dots_param) \
  80     __attribute__((format(printf, format_param, dots_param)))
  81
  82 // WPRINTF_FORMAT is the same, but for wide format strings.
  83 // This doesn't appear to yet be implemented.
  84 // See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38308 .
  85 #define WPRINTF_FORMAT(format_param, dots_param)
  86 // If available, it would look like:
  87 //   __attribute__((format(wprintf, format_param, dots_param)))
  88
  89 #else  // Not GCC
  90
  91 #define ALLOW_UNUSED
  92 #define WARN_UNUSED_RESULT
  93 #define PRINTF_FORMAT(x, y)
  94 #define WPRINTF_FORMAT(x, y)
  95
  96 #endif
  97
  98 #endif  // BASE_COMPILER_SPECIFIC_H_