ubuntu 14.04 Clang編譯安裝，libclang解析c++代碼

注意事項：

1. 內存8G以上，我當時4G內存，編譯debug版就出現了內存耗盡的情況；

2.最好不要編譯debug版本，我編譯到83%左右時已經耗盡30多G磁盤空間，並且會產生很大的編譯日誌文件（提示12G左右），同樣提示內存不足

針對內存耗盡的問題，當時也在網上找了很久，來自於stackoverflow（https://stackoverflow.com/questions/25197570/llvm-clang-compile-error-with-memory-exhausted）的回答：

1. Add more RAM to your VM, or
2. Use gold instead of ld as a linker, or (sudo ln -s `which gold` /usr/local/bin/ld)
3. Build Release, not Debug build

關於源碼，可以去官網下載：下載地址， 也可以從svn上面checkout下來，具體的編譯過程可以參考官網的指南：http://clang.llvm.org/get_started.html，如下：

If you would like to check out and build Clang, the current procedure is as follows:

1. Get the required tools.
   • See Getting Started with the LLVM System - Requirements.
   • Note also that Python is needed for running the test suite. Get it at: http://www.python.org/download
   • Standard build process uses CMake. Get it at: http://www.cmake.org/download
2. Check out LLVM:
   • Change directory to where you want the llvm directory placed.
   • svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm
3. Check out Clang:
   • cd llvm/tools
   • svn co http://llvm.org/svn/llvm-project/cfe/trunk clang
   • cd ../..
4. Check out extra Clang tools: (optional)
   • cd llvm/tools/clang/tools
   • svn co http://llvm.org/svn/llvm-project/clang-tools-extra/trunk extra
   • cd ../../../..
5. Check out Compiler-RT (optional):（不需要）
   • cd llvm/projects
   • svn co http://llvm.org/svn/llvm-project/compiler-rt/trunk compiler-rt
   • cd ../..
6. Check out libcxx: (only required to build and run Compiler-RT tests on OS X, optional otherwise)（不需要）
   • cd llvm/projects
   • svn co http://llvm.org/svn/llvm-project/libcxx/trunk libcxx
   • cd ../..
7. Build LLVM and Clang:
   • mkdir build (in-tree build is not supported)
   • cd build
   • cmake -G "Unix Makefiles" ../llvm（最好用 cmake -G "Unix Makefiles"-DCMAKE_BUILD_TYPE:String=Release ../llvm， 編譯release版本，debug版本有三十多G）
   • make
   • This builds both LLVM and Clang for debug mode.
   • Note: For subsequent Clang development, you can just run make clang.
   • CMake allows you to generate project files for several IDEs: Xcode, Eclipse CDT4, CodeBlocks, Qt-Creator (use the CodeBlocks generator), KDevelop3. For more details see Building LLVM with CMake page.
8. If you intend to use Clang's C++ support, you may need to tell it how to find your C++ standard library headers. In general, Clang will detect the best version of libstdc++ headers available and use them - it will look both for system installations of libstdc++ as well as installations adjacent to Clang itself. If your configuration fits neither of these scenarios, you can use the -DGCC_INSTALL_PREFIX cmake option to tell Clang where the gcc containing the desired libstdc++ is installed.
9. Try it out (assuming you add llvm/build/bin to your path):
   • clang --help
   • clang file.c -fsyntax-only (check for correctness)
   • clang file.c -S -emit-llvm -o - (print out unoptimized llvm code)
   • clang file.c -S -emit-llvm -o - -O3
   • clang file.c -S -O3 -o - (output native machine code)
10. Run the testsuite:（不需要）
    • make check-clang
      

接下來就是如何利用libclang對c++代碼進行抽象語法樹生成，以及關鍵字提取。參考：https://shaharmike.com/cpp/libclang/

#include <iostream>
#include <clang-c/Index.h>
using namespace std;

ostream& operator<<(ostream& stream, const CXString& str)
{
  stream << clang_getCString(str);
  clang_disposeString(str);
  return stream;
}

int main()
{
  CXIndex index = clang_createIndex(0, 0);
  CXTranslationUnit unit = clang_parseTranslationUnit(
    index,
    "header.hpp", nullptr, 0,
    nullptr, 0,
    CXTranslationUnit_None);
  if (unit == nullptr)
  {
    cerr << "Unable to parse translation unit. Quitting." << endl;
    exit(-1);
  }

  CXCursor cursor = clang_getTranslationUnitCursor(unit);
  clang_visitChildren(
    cursor,
    [](CXCursor c, CXCursor parent, CXClientData client_data)
    {
      cout << "Cursor '" << clang_getCursorSpelling(c) << "' of kind '"
        << clang_getCursorKindSpelling(clang_getCursorKind(c)) << "'\n";
      return CXChildVisit_Recurse;
    },
    nullptr);

  clang_disposeTranslationUnit(unit);
  clang_disposeIndex(index);
}

header.hpp

enum class Cpp11Enum
{
  RED = 10,
  BLUE = 20
};

struct Wowza
{
  virtual ~Wowza() = default;
  virtual void foo(int i = 0) = 0;
};

struct Badabang : Wowza
{
  void foo(int) override;

  bool operator==(const Badabang& o) const;
};

template <typename T>
void bar(T&& t);