如何使用 include-what-you-use 工具与 CMake 一起检测未使用的标头？

Question

工具include-what-you-use 可用于检测不需要的标头。我在我的 C++ 软件项目中使用CMake。如何指示 CMake 在我的软件项目的源文件中自动运行 include-what-you-use？

Answer 1

CMake 3.3引入了新的目标属性CXX_INCLUDE_WHAT_YOU_USE，可以设置为程序include-what-you-use的路径。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 REQUIRED)

# If using CGAL<3.18, you remove REQUIRED and use
# 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})

能够构建文件main.cc

#include <iostream>
#include <vector>

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

同时有include-what-you-use发出警告 不需要包含的标题 vector。

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$

如果您想将自定义选项传递给include-what-you-use，例如--mapping_file，您可以通过

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，include-what-you-use 附带一个名为 iwyu_tool.py 的 Python 工具，它可以做您想做的事情。

它通过解析 JSON 编译数据库来工作，该数据库很容易用 CMake 生成（见下文）。

手动运行工具

假设您的项目已经有一个 CMake 构建目录，您首先需要告诉 CMake 生成编译数据库：

$ cd build
$ cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON .

这会生成一个文件compile_commands.json，其中包含项目中每个目标文件的编译器调用。您无需重新构建项目。

您现在可以通过在构建目录上运行 python 工具在您的项目上运行 include-what-you-use：

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

为您的 cmake 项目添加自定义目标

下面的sn-p可以用来给cmake项目添加iwyu目标。

# 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()

注意事项

include-what-you-use 二进制文件需要在您的路径中，以上任何一项才能正常工作。

默认情况下，iwyu_tool.py 是单线程的，这对于大型项目可能会很慢。您可以使用--jobs 参数来增加将并行处理的源文件的数量。

Answer 3

您也可以通过设置 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。

Answer 4

我扩展了 Alastair Harrison 的源代码，以创建可重用的解决方案。我想出了以下应该适用于 all CMake 版本：

文件iwyu.cmake：

#.rst:
# include-what-you-use (iwyu)
# ----------------------------
#
# Allows to run the static code analyzer `include-what-you-use (iwyu)
# <http://include-what-you-use.org>`_ as a custom target with the build system
# `CMake <http://cmake.org>`_.
#
# .. topic:: Dependencies
#
#  This module requires the following *CMake* modules:
#
#  * ``FindPythonInterp``
#
# .. topic:: Contributors
#
#  * Florian Wolters <wolters.fl@gmail.com>

#===============================================================================
# Copyright 2015 Florian Wolters
#
# Distributed under the Boost Software License, Version 1.0. (See accompanying
# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
#===============================================================================

# ------------------------------------------------------------------------------
# Include guard for this file.
# ------------------------------------------------------------------------------

if(iwyu_included)
  return()
endif()

set(iwyu_included TRUE)

option(BUILD_IWYU
       "Run the include-what-you-use static analyzer on the source code of the project."
       OFF)

function(iwyu_enable)
  set(iwyu_EXECUTABLE_NAME include-what-you-use)
  find_program(iwyu_EXECUTABLE ${iwyu_EXECUTABLE_NAME})

  if(iwyu_EXECUTABLE)
    # This is not exactly the same behavior as with CMake v3.3, since here all
    # compiled targets are analyzed.
    set(iwyu_tool_EXECUTABLE_NAME iwyu_tool.py)

    find_package(PythonInterp)
    find_program(iwyu_tool_EXECUTABLE ${iwyu_tool_EXECUTABLE_NAME})

    if(PYTHONINTERP_FOUND AND iwyu_tool_EXECUTABLE)
      set(CMAKE_EXPORT_COMPILE_COMMANDS ON PARENT_SCOPE)

      add_custom_target(iwyu
                        ALL
                        COMMAND "${PYTHON_EXECUTABLE}" "${iwyu_tool_EXECUTABLE}" -p "${CMAKE_BINARY_DIR}"
                        COMMENT "Running the ${iwyu_tool_EXECUTABLE_NAME} compilation database driver"
                        VERBATIM)
    else()
      message(STATUS
              "Unable to find the Python interpreter and/or the ${iwyu_tool_EXECUTABLE_NAME} script")
    endif()
  else()
    message(STATUS "Unable to find the ${iwyu_EXECUTABLE_NAME} executable")
  endif()
endfunction()

文件CMakeLists.txt：

cmake_minimum_required(VERSION 3.0)

include(iwyu.cmake)

project(hello_world)
add_executable(${PROJECT_NAME} main.cc)

if(BUILD_IWYU)
  iwyu_enable()
endif()

如下调用 CMake 以在调用 all 目标时运行 include-what-you-use：

cmake -DBUILD_IWYU=ON <path-to-source>
cmake --build . --target all

输出应该如下：

-- Configuring done
-- Generating done
-- Build files have been written to: /home/wolters/workspace/include-what-you-use_example/build
[ 66%] Built target hello_world
[100%] Running the iwyu_tool.py compilation database driver

/home/wolters/workspace/include-what-you-use_example/develop/main.cc should add these lines:

/home/wolters/workspace/include-what-you-use_example/develop/main.cc should remove these lines:
- #include <vector>  // lines 1-1

The full include-list for /home/wolters/workspace/include-what-you-use_example/develop/main.cc:
#include <iostream>  // for operator<<, basic_ostream, cout, endl, ostream
---
[100%] Built target iwyu

编辑 2015-08-19： CMake 属性 <LANG>_INCLUDE_WHAT_YOU_USE 的方法不适用于 CMake 3.3 版。 1.因此我更新了解决方案。

编辑 2015-09-30： 输出错误，因为我的 include-what-you-use 安装已损坏。 include-what-you-use 和 iwyu_tool.py 文件必须与 clang、clang++ 等位于同一目录中。