问题描述
C ++标准委员会正在致力于概念扩展的TS（技术规范）：编程语言 - 概念的C + +扩展。 是本文档的最新版本。
The C++ standards committee is working on a TS (Technical Specification) for Concepts extension: "Programming Languages - C++ Extensions for Concepts". N4377 is the latest version of this document. For inclusion into the C++ standard features are asked to be implemented, ideally for a publicly accessible system.
我知道，但上述概念提案（通俗地称为 Concepts Lite ）是不同的。我听说有一个概念分支，我尝试了来自的 git 镜像，但没有编译。如何构建和使用上述[draft] TS中指定的gcc支持概念的版本？
I'm aware of concept-gcc but the concepts proposal above (colloquially referred to as Concepts Lite) is different. I heard that there is a concepts branch and I have tried the origin/asutton/c++-concepts from gcc's git mirror but that didn't compile. How do I build and use a version of gcc supporting concepts as specified in the above [draft] TS?
推荐答案
Sutton Concepts Lite工作的git镜像完全是过时的，不应该使用。在svn存储库中有一个概念分支，用于实现concepts-lite（有一个前C ++ 11努力添加概念到C ++被放弃;一个新的努力添加概念到C + +开始使用名称概念lite）。这是相当直接的构建（假设你已经有一个最近的gcc和包取决于安装;请参阅gcc安装说明其他选项，你可能想通过：下面的说明为我工作，除了我明确指出<$在，，并安装了）：
According to Andrew Sutton the git mirror of the Concepts Lite work is entirely out of date and shouldn't be used. There is a concepts branch in the svn repository for gcc implementing "concepts-lite" (there was a pre-C++11 effort to add concepts to C++ which was abandoned; a new effort to add concepts to C++ was started using the name concepts lite). It is fairly straight forward to build (assuming you already have a recent gcc and the packages it depends on installed; see the gcc install instruction for other options you might want to pass: the instructions below worked for me except that I explicitly pointed configure at the locations where gmp, mpc, and mpfr are installed):
cd <suitable-directory>
svn checkout svn://gcc.gnu.org/svn/gcc/branches/c++-concepts
mkdir build-concepts
cd build-concepts
../c++-concepts/configure --prefix=<concept-gcc-root> --disable-bootstrap --enable-languages=c,c++
make -j8
make install
b $ b
什么并不完全明显是如何实际使用概念：选项 -fconcepts 确实存在，但似乎无条件做不同于启用概念 - 精简。相反，在启用概念的编译时，您可以使用 -std = c ++ 1z 选项。
What isn't entirely obvious is how to actually use concepts: the option -fconcepts does exist but seems to unconditionally do something different than enabling concepts-lite. Instead, you'd use the -std=c++1z option when compiling with concepts enabled.
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