Move OS/compiler/feature detection to public v8config.h header.

include/v8config.h

+// Copyright 2013 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8CONFIG_H_
+#define V8CONFIG_H_
+
+// -----------------------------------------------------------------------------
+// Operating system detection
+//
+//  V8_OS_ANDROID       - Android
+//  V8_OS_BSD           - BSDish (Mac OS X, Net/Free/Open/DragonFlyBSD)
+//  V8_OS_CYGWIN        - Cygwin
+//  V8_OS_DRAGONFLYBSD  - DragonFlyBSD
+//  V8_OS_FREEBSD       - FreeBSD
+//  V8_OS_LINUX         - Linux
+//  V8_OS_MACOSX        - Mac OS X
+//  V8_OS_NACL          - Native Client
+//  V8_OS_NETBSD        - NetBSD
+//  V8_OS_OPENBSD       - OpenBSD
+//  V8_OS_POSIX         - POSIX compatible (mostly everything except Windows)
+//  V8_OS_SOLARIS       - Sun Solaris and OpenSolaris
+//  V8_OS_WIN           - Microsoft Windows
+
+#if defined(__ANDROID__)
+# define V8_OS_ANDROID 1
+# define V8_OS_LINUX 1
+# define V8_OS_POSIX 1
+#elif defined(__APPLE__)
+# define V8_OS_BSD 1
+# define V8_OS_MACOSX 1
+# define V8_OS_POSIX 1
+#elif defined(__native_client__)
+# define V8_OS_NACL 1
+# define V8_OS_POSIX 1
+#elif defined(__CYGWIN__)
+# define V8_OS_CYGWIN 1
+# define V8_OS_POSIX 1
+#elif defined(__linux__)
+# define V8_OS_LINUX 1
+# define V8_OS_POSIX 1
+#elif defined(__sun)
+# define V8_OS_POSIX 1
+# define V8_OS_SOLARIS 1
+#elif defined(__FreeBSD__)
+# define V8_OS_BSD 1
+# define V8_OS_FREEBSD 1
+# define V8_OS_POSIX 1
+#elif defined(__DragonFly__)
+# define V8_OS_BSD 1
+# define V8_OS_DRAGONFLYBSD 1
+# define V8_OS_POSIX 1
+#elif defined(__NetBSD__)
+# define V8_OS_BSD 1
+# define V8_OS_NETBSD 1
+# define V8_OS_POSIX 1
+#elif defined(__OpenBSD__)
+# define V8_OS_BSD 1
+# define V8_OS_OPENBSD 1
+# define V8_OS_POSIX 1
+#elif defined(_WIN32)
+# define V8_OS_WIN 1
+#endif
+
+
+// -----------------------------------------------------------------------------
+// Compiler detection
+//
+//  V8_CC_CLANG   - Clang
+//  V8_CC_GNU     - GNU C++
+//  V8_CC_MINGW   - Minimalist GNU for Windows
+//  V8_CC_MSVC    - Microsoft Visual C/C++
+//
+// C++11 feature detection
+//
+//  V8_HAS_CXX11_ALIGNAS        - alignas specifier supported
+//  V8_HAS_CXX11_STATIC_ASSERT  - static_assert() supported
+//  V8_HAS_CXX11_DELETE         - deleted functions supported
+//  V8_HAS_CXX11_FINAL          - final marker supported
+//  V8_HAS_CXX11_OVERRIDE       - override marker supported
+//
+// Compiler-specific feature detection
+//
+//  V8_HAS_ATTRIBUTE___ALIGNED__    - __attribute__((__aligned__(n))) supported
+//  V8_HAS_ATTRIBUTE_ALWAYS_INLINE  - __attribute__((always_inline)) supported
+//  V8_HAS_ATTRIBUTE_DEPRECATED     - __attribute__((deprecated)) supported
+//  V8_HAS_ATTRIBUTE_VISIBILITY     - __attribute__((visibility)) supported
+//  V8_HAS_BUILTIN_EXPECT           - __builtin_expect() supported
+//  V8_HAS_DECLSPEC_ALIGN           - __declspec(align(n)) supported
+//  V8_HAS_DECLSPEC_DEPRECATED      - __declspec(deprecated) supported
+//  V8_HAS___FINAL                  - __final supported in non-C++11 mode
+//  V8_HAS___FORCEINLINE            - __forceinline supported
+//  V8_HAS_SEALED                   - MSVC style sealed marker supported
+
+#if defined(__clang__)

[Nico, 2014/11/26 21:43:20]

This doesn't look like a good approach to me. Clang tries to look like gcc, or
like cl.exe, depending on how it's invoked. All of other chrome's projects let
their COMPILER_GCC include clang in gcc mode, and their COMPILER_MSVC clang in
ms mode, and then use a dedicated #if __clang__ in the few places where this
doesn't work out. Was this approach considered?

The concrete reason why I'm looking at this: the V8_INT64_C macros are
incorrectly set when building with clang on Windows because clang isn't allowed
to go down the V8_CC_MSVC path in macros.h – and the non-msvc path then thinks
that "l" is the correct format string for pointers. But while "long" is 64bit in
64bit builds on posix, it isn't on Windows. I could fix that macro, but I think
a better fix would be to get rid of V8_CC_CLANG and let clang be included in the
gcc and msvc code paths. I'm happy to do this work if this sounds acceptable to
you.

[Benedikt Meurer, 2014/12/01 18:02:00]

So you're talking about either setting both V8_CC_CLANG and V8_CC_GNU or setting
both V8_CC_CLANG and V8_CC_MSVC? That'll require some careful changes to several
files.

[Nico, 2014/12/01 18:03:48]

Yes, I'd let clang set V8_CC_GNU or V8_CC_MSVC (depending on which mode it
emulates).

Maybe I'd even try to get rid of V8_CC_CLANG.

[Nico, 2014/12/01 20:10:08]

It looks like it Just Works: https://codereview.chromium.org/757553004/

Maybe I didn't look for the right files? Were you thinking of anything in
particular?

+
+// Don't treat clang as GCC.
+# define V8_GNUC_PREREQ(major, minor, patchlevel) 0
+
+# define V8_CC_CLANG 1
+
+# define V8_HAS_ATTRIBUTE___ALIGNED__ (__has_attribute(__aligned__))
+# define V8_HAS_ATTRIBUTE_ALWAYS_INLINE (__has_attribute(always_inline))
+# define V8_HAS_ATTRIBUTE_DEPRECATED (__has_attribute(deprecated))
+# define V8_HAS_ATTRIBUTE_VISIBILITY (__has_attribute(visibility))
+
+# define V8_HAS_BUILTIN_EXPECT (__has_builtin(__builtin_expect))
+
+# define V8_HAS_CXX11_ALIGNAS (__has_feature(cxx_alignas))
+# define V8_HAS_CXX11_STATIC_ASSERT (__has_feature(cxx_static_assert))
+# define V8_HAS_CXX11_DELETE (__has_feature(cxx_deleted_functions))
+# define V8_HAS_CXX11_FINAL (__has_feature(cxx_override_control))
+# define V8_HAS_CXX11_OVERRIDE (__has_feature(cxx_override_control))
+
+#elif defined(__GNUC__)
+
+# define V8_GNUC_PREREQ(major, minor, patchlevel)                         \
+    ((__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) >=   \
+     ((major) * 10000 + (minor) * 100 + (patchlevel)))
+
+# define V8_CC_GNU 1
+# if defined(__MINGW32__)
+#  define V8_CC_MINGW 1
+# endif
+
+# define V8_HAS_ATTRIBUTE___ALIGNED__ (V8_GNUC_PREREQ(2, 95, 0))
+# define V8_HAS_ATTRIBUTE_ALWAYS_INLINE (V8_GNUC_PREREQ(4, 0, 0))
+# define V8_HAS_ATTRIBUTE_DEPRECATED (V8_GNUC_PREREQ(3, 4, 0))
+# define V8_HAS_ATTRIBUTE_VISIBILITY (V8_GNUC_PREREQ(4, 3, 0))
+
+# define V8_HAS_BUILTIN_EXPECT (V8_GNUC_PREREQ(2, 96, 0))
+
+// g++ requires -std=c++0x or -std=gnu++0x to support C++11 functionality
+// without warnings (functionality used by the macros below).  These modes
+// are detectable by checking whether __GXX_EXPERIMENTAL_CXX0X__ is defined or,
+// more standardly, by checking whether __cplusplus has a C++11 or greater
+// value. Current versions of g++ do not correctly set __cplusplus, so we check
+// both for forward compatibility.
+# if defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L
+#  define V8_HAS_CXX11_ALIGNAS (V8_GNUC_PREREQ(4, 8, 0))
+#  define V8_HAS_CXX11_STATIC_ASSERT (V8_GNUC_PREREQ(4, 3, 0))
+#  define V8_HAS_CXX11_DELETE (V8_GNUC_PREREQ(4, 4, 0))
+#  define V8_HAS_CXX11_OVERRIDE (V8_GNUC_PREREQ(4, 7, 0))
+#  define V8_HAS_CXX11_FINAL (V8_GNUC_PREREQ(4, 7, 0))
+# else
+// '__final' is a non-C++11 GCC synonym for 'final', per GCC r176655.
+#  define V8_HAS___FINAL (V8_GNUC_PREREQ(4, 7, 0))
+# endif
+
+#elif defined(_MSC_VER)
+
+# define V8_GNUC_PREREQ(major, minor, patchlevel) 0
+
+# define V8_CC_MSVC 1
+
+// Override control was added with Visual Studio 2005, but
+// Visual Studio 2010 and earlier spell "final" as "sealed".
+# define V8_HAS_CXX11_FINAL (_MSC_VER >= 1700)
+# define V8_HAS_CXX11_OVERRIDE (_MSC_VER >= 1400)
+# define V8_HAS_SEALED (_MSC_VER >= 1400)
+
+# define V8_HAS_DECLSPEC_ALIGN 1
+# define V8_HAS_DECLSPEC_DEPRECATED (_MSC_VER >= 1300)
+
+# define V8_HAS___FORCEINLINE 1
+
+#endif
+
+
+// -----------------------------------------------------------------------------
+// Helper macros
+
+// A macro used to make better inlining. Don't bother for debug builds.
+#if !defined(DEBUG) && V8_HAS_ATTRIBUTE_ALWAYS_INLINE
+# define V8_INLINE(declarator) inline __attribute__((always_inline)) declarator
+#elif !defined(DEBUG) && V8_HAS___FORCEINLINE
+# define V8_INLINE(declarator) __forceinline declarator
+#else
+# define V8_INLINE(declarator) inline declarator
+#endif
+
+
+// A macro to mark classes or functions as deprecated.
+#if !V8_DISABLE_DEPRECATIONS && V8_HAS_ATTRIBUTE_DEPRECATED
+# define V8_DEPRECATED(declarator) declarator __attribute__((deprecated))
+#elif !V8_DISABLE_DEPRECATIONS && V8_HAS_DECLSPEC_DEPRECATED
+# define V8_DEPRECATED(declarator) __declspec(deprecated) declarator
+#else
+# define V8_DEPRECATED(declarator) declarator
+#endif
+
+
+// A macro to provide the compiler with branch prediction information.
+#if V8_HAS_BUILTIN_EXPECT
+# define V8_UNLIKELY(condition) (__builtin_expect(!!(condition), 0))
+# define V8_LIKELY(condition) (__builtin_expect(!!(condition), 1))
+#else
+# define V8_UNLIKELY(condition) (condition)
+# define V8_LIKELY(condition) (condition)
+#endif
+
+
+// A macro to specify that a method is deleted from the corresponding class.
+// Any attempt to use the method will always produce an error at compile time
+// when this macro can be implemented (i.e. if the compiler supports C++11).
+// If the current compiler does not support C++11, use of the annotated method
+// will still cause an error, but the error will most likely occur at link time
+// rather than at compile time. As a backstop, method declarations using this
+// macro should be private.
+// Use like:
+//   class A {
+//    private:
+//     A(const A& other) V8_DELETE;
+//     A& operator=(const A& other) V8_DELETE;
+//   };
+#if V8_HAS_CXX11_DELETE
+# define V8_DELETE = delete
+#else
+# define V8_DELETE /* NOT SUPPORTED */
+#endif
+
+
+// Annotate a virtual method indicating it must be overriding a virtual
+// method in the parent class.
+// Use like:
+//   virtual void bar() V8_OVERRIDE;
+#if V8_HAS_CXX11_OVERRIDE
+# define V8_OVERRIDE override
+#else
+# define V8_OVERRIDE /* NOT SUPPORTED */
+#endif
+
+
+// Annotate a virtual method indicating that subclasses must not override it,
+// or annotate a class to indicate that it cannot be subclassed.
+// Use like:
+//   class B V8_FINAL : public A {};
+//   virtual void bar() V8_FINAL;
+#if V8_HAS_CXX11_FINAL
+# define V8_FINAL final
+#elif V8_HAS___FINAL
+# define V8_FINAL __final
+#elif V8_HAS_SEALED
+# define V8_FINAL sealed
+#else
+# define V8_FINAL /* NOT SUPPORTED */
+#endif
+
+
+// This macro allows to specify memory alignment for structs, classes, etc.
+// Use like:
+//   class V8_ALIGNAS(16) MyClass { ... };
+//   V8_ALIGNAS(32) int array[42];
+#if V8_HAS_CXX11_ALIGNAS
+# define V8_ALIGNAS(n) alignas(n)
+#elif V8_HAS_ATTRIBUTE___ALIGNED__
+# define V8_ALIGNAS(n) __attribute__((__aligned__(n)))
+#elif V8_HAS_DECLSPEC_ALIGN
+# define V8_ALIGNAS(n) __declspec(align(n))
+#else
+# define V8_ALIGNAS(n) /* NOT SUPPORTED */
+#endif
+
+#endif  // V8CONFIG_H_