如何使用该工具包括你和CMake一起使用什么来检测未使用的标头？

Question

该工具include-what-you-use可用于检测不需要的标头.我正在使用CMake来完成我的C++软件项目.如何指示CMake在我的软件项目的源文件上自动运行包含什么？

Answer 1

CMake 3.3引入了新的目标属性CXX_INCLUDE_WHAT_YOU_USE,可以将其设置为程序的路径include-what-you-use.例如,这个CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)
add_executable(hello main.cc)

find_program(iwyu_path NAMES include-what-you-use iwyu)
if(NOT iwyu_path)
  message(FATAL_ERROR "Could not find the program include-what-you-use")
endif()

set_property(TARGET hello PROPERTY CXX_INCLUDE_WHAT_YOU_USE ${iwyu_path})

能够构建main.cc文件

#include <iostream>
#include <vector>

int main() {
  std::cout << "Hello World!" << std::endl;
  return 0;
}

同时include-what-you-use发出警告说不需要包含的标题向量.

user@ubuntu:/tmp$ ls ~/hello
CMakeLists.txt  main.cc
user@ubuntu:/tmp$ mkdir /tmp/build
user@ubuntu:/tmp$ cd /tmp/build
user@ubuntu:/tmp/build$ ~/cmake-3.3.0-rc2-Linux-x86_64/bin/cmake ~/hello
-- The C compiler identification is GNU 4.9.2
-- The CXX compiler identification is GNU 4.9.2
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /tmp/build
user@ubuntu:/tmp/build$ make
Scanning dependencies of target hello
[ 50%] Building CXX object CMakeFiles/hello.dir/main.cc.o
Warning: include-what-you-use reported diagnostics:

/home/user/hello/main.cc should add these lines:

/home/user/hello/main.cc should remove these lines:
- #include <vector>  // lines 2-2

The full include-list for /home/user/hello/main.cc:
#include <iostream>  // for operator<<, basic_ostream, cout, endl, ostream
---

[100%] Linking CXX executable hello
[100%] Built target hello
user@ubuntu:/tmp/build$ ./hello 
Hello World!
user@ubuntu:/tmp/build$

如果你想传递自定义选项include-what-you-use,比如--mapping_file你可以通过

set(iwyu_path_and_options
    ${iwyu_path}
    -Xiwyu
    --mapping_file=${my_mapping})

set_property(TARGET hello
    PROPERTY CXX_INCLUDE_WHAT_YOU_USE ${iwyu_path_and_options})

Answer 2

如果您无法访问CMake 3.3,则include-what-you-use附带一个名为iwyu_tool.py的python工具,可以执行您想要的操作.

它的工作原理是解析一个使用CMake轻松生成的clang编译数据库.

手动运行该工具

假设您的项目已有CMake构建目录,首先需要告诉CMake生成编译数据库:

$ cd build
$ cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON .

这将生成一个文件,compile_commands.json其中包含项目中每个目标文件的编译器调用.您无需重建项目.

您现在可以include-what-you-use通过在构建目录上运行python工具来运行您的项目:

$ python /path/to/iwyu_tool.py -p .

将自定义目标添加到您的cmake项目

以下代码段可用于将iwyu目标添加到cmake项目.

# Generate clang compilation database
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

find_package(PythonInterp)
find_program(iwyu_tool_path NAMES iwyu_tool.py)
if (iwyu_tool_path AND PYTHONINTERP_FOUND)
  add_custom_target(iwyu
    ALL      # Remove ALL if you don't iwyu to be run by default.
    COMMAND "${PYTHON_EXECUTABLE}" "${iwyu_tool_path}" -p "${CMAKE_BINARY_DIR}"
    COMMENT "Running include-what-you-use tool"
    VERBATIM
  )
endif()

笔记

该include-what-you-use二进制需要在你的路径任何上述的正常工作.

Answer 3

您还可以通过设置cmake变量在cmake脚本之外全局启用它:

cmake -DCMAKE_CXX_INCLUDE_WHAT_YOU_USE="iwyu" <builddir> 

然后它将在每个CXX目标上调用它.