| C++11 in Skia |
| ============= |
| |
| Skia uses C++11. But as a library, we are technically limited by what our |
| clients support and what our build bots support. |
| |
| Skia may also be limited by restrictions we choose put on ourselves. This |
| document is not concerned with C++11 policy in Skia, only its technical |
| feasibility. This is about what we can use, a superset of what we may use. |
| |
| The gist: |
| |
| - C++11 the language as supported by GCC 4.7 or later is pretty usable. |
| - The C++11 standard library can generally be used, with some teething. |
| - If you break a bot, that feature is not usable. |
| - Local statics are not thread safe. |
| |
| |
| Clients |
| ------- |
| |
| The clients we pay most attention to are Chrome, Android, Mozilla, and a few |
| internal Google projects. |
| |
| Chrome builds with a recent Clang on Mac and Linux and with a recent MSVC on |
| Windows. These toolchains are new enough to not be the weak link to use any |
| C++11 language feature. Chromium, however, builds against libstdc++4.6.4 |
| (STL and runtime) on Linux. This precludes direct use of a number of type |
| traits. |
| |
| Chrome intentionally disables thread-safe initialization of static variables, |
| so we cannot rely on that. Our bots disable this too, so keep an eye on TSAN. |
| |
| Android builds with either a somewhat aged GCC or a recent Clang. They're |
| generally not a weak link for C++11 language features. Android's C++ standard |
| library had historically been a pain, but seems to work fine these days. |
| |
| Mozilla's current weak link is a minimum requirement of GCC 4.7. Most features |
| marked in red on Mozilla's C++11 [feature |
| matrix](https://developer.mozilla.org/en-US/docs/Using_CXX_in_Mozilla_code) are |
| marked that way because they arrived in GCC 4.8. Their minimum-supported Clang |
| and MSVC toolchains are pretty good, but MSVC 2013 will become the weak link soon. |
| |
| Internal Google projects tend to support C++11 completely, including the |
| full C++11 standard library. |
| |
| |
| Bots |
| ---- |
| |
| Most of our bots are pretty up-to-date: the Windows bots use MSVC 2013, the Mac |
| bots a recent Clang, and the Linux bots GCC 4.8 or a recent Clang. Our Android |
| bots use a recent toolchain from Android (see above), and our Chrome bots use |
| Chrome's toolchains (see above). I'm not exactly sure what our Chrome OS bots |
| are using. They're probably our weak link right now, though problems are rare. |
| |
| I believe our bots' ability to use C++11 matches Mozilla's list nearly identically. |
