【问题标题】：How to set up Doxygen and CMake for builds that generate headerfiles during the build process?如何为在构建过程中生成头文件的构建设置 Doxygen 和 CMake？
【发布时间】：2021-12-19 15:06:22
【问题描述】：

概述

我的 CMake 项目中的一些头文件是在构建过程中自动生成的。我的目标是设置CMakeLists.txt，以便为我的项目构建文档也会触发头文件生成（不触发任何其他构建）。基本的 CMake/Doxygen 设置遵循此 MS tutorial 的初始步骤。

详情

这个项目的目录结构有些不合常规：

${CMAKE_SOURCE_DIR} 是 cmake/ 持有顶级 CMakeLists.txt 文件，${CMAKE_BINARY_DIR} 是 cmake/cmake-build-debug。

我希望生成的文档以cmake/cmake-build-debug/docs 结尾。但是，我想将 CMake 和 Doxygen 配置提交到存储库，因此这些文件位于 docs/ 中。

源文件如下：

squawk.cpp:

#include "squawk.hpp"

void squawk(const std::string &s) {
    std::cout<<STRFY(SQUAWK)<<": "<<s<<std::endl;
}

squawk.hpp:

#include <iostream>
#include <string>

#define STRINGIFY(X) #X
#define STRFY(X) STRINGIFY(X)
#include "squawk.hd"

void squawk(const std::string &s);

main.cpp:

#include "squawk.hpp"

int main(int argc, char* argv[]) {

    const std::string s = "Hello World!";
    squawk(s);

    return 0;
}

squawk.def:
```
#define SQUAWK squeal
```

在构建过程中我取squawk.def，将squeal改成caw并保存为squawk.hd，由sed执行，指令在squawk.ss:s/(#define SQUAWK)(.*)/\1 caw/。这是头文件的生成过程。即使我只是构建文档而无需构建 squawk 二进制文件，我也希望发生这种情况。

【问题讨论】：

标签： c++ cmake doxygen

【解决方案1】：

解决方案

解决此问题的关键是使用add_custom_target 而不是add_custom_command 生成头文件。

cmake/CMakeLists.txt:

### Set variables ###
set(SRC_DIR ${CMAKE_CURRENT_SOURCE_DIR}/../src)
set(SOURCES ${SRC_DIR}/squawk.cpp
    ${SRC_DIR}/main.cpp)
set(SQUAWK_DEF ${SRC_DIR}/squawk.def)
set(SQUAWK_SCRIPT ${CMAKE_CURRENT_SOURCE_DIR}/squawk.ss)
# Create include/ dir to save generated .hd file
set(INCLUDE_DIR ${CMAKE_CURRENT_BINARY_DIR}/include)
file(MAKE_DIRECTORY ${INCLUDE_DIR})
set(SQUAWK_HD ${INCLUDE_DIR}/squawk.hd)
set(BIN_NAME squawk)

### Generate .hd file ###
add_custom_target(gen_hd
        BYPRODUCTS ${SQUAWK_HD}
        DEPENDS ${SQUAWK_DEF}
        SOURCES ${SQUAWK_DEF} ${SQUAWK_SCRIPT}
        COMMAND sed --regexp-extended -f ${SQUAWK_SCRIPT} ${SQUAWK_DEF} >${SQUAWK_HD})

### Add target ###
add_executable(${BIN_NAME}
    ${SOURCES}
    ${SQUAWK_HD})
target_include_directories(${BIN_NAME} PUBLIC
    ${INCLUDE_DIR})

### Build documentation ###
if(DOCUMENTATION)
    add_subdirectory(../docs ${CMAKE_CURRENT_BINARY_DIR}/docs)
endif()

docs/CMakeLists.txt:

### Find Doxygen ###
# We need Doxygen 1.9.2 or higher
find_package(Doxygen 1.9.2 REQUIRED)

### Find headers ###
get_target_property(SQUAWK_PUBLIC_HEADER_DIR ${BIN_NAME} INTERFACE_INCLUDE_DIRECTORIES)
set(SQUAWK_PUBLIC_HEADERS "")
foreach(d ${SQUAWK_PUBLIC_HEADER_DIR})
    file(GLOB_RECURSE SPH ${d}/*.h*)
    list(APPEND SQUAWK_PUBLIC_HEADERS ${SPH})
endforeach()

### Set Doxygen variables ###
# Set variables which will be subsituted
# in the Doxyfile.in for INPUT and OUTPUT
set(DOXYGEN_INPUT_DIR "${SQUAWK_PUBLIC_HEADER_DIR}" "${SOURCES}")
# Replace ; with space so string adheres to Doxygen syntax
string(REPLACE ";" " " DOXYGEN_INPUT_DIR "${DOXYGEN_INPUT_DIR}")
set(DOXYGEN_OUTPUT_DIR "${CMAKE_BINARY_DIR}/docs")

### Generate Doxyfile ###
# Use docs/Doxyfile.in and configure_file
# to create cmake/docs/Doxyfile which will be used
# to generate the documentation
set(DOXYFILE_IN ${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile.in)
set(DOXYFILE_OUT ${DOXYGEN_OUTPUT_DIR}/Doxyfile)
configure_file(${DOXYFILE_IN} ${DOXYFILE_OUT} @ONLY)

### Run Doxygen ###
# Create directory where documentation will live
# Specify index file which will be the output of the command
# Add command and target
file(MAKE_DIRECTORY ${DOXYGEN_OUTPUT_DIR})
set(DOXYGEN_INDEX_FILE ${DOXYGEN_OUTPUT_DIR}/html/index.html)
    add_custom_command(OUTPUT ${DOXYGEN_INDEX_FILE}
            COMMAND ${DOXYGEN_EXECUTABLE} Doxyfile
            MAIN_DEPENDENCY "${DOXYFILE_IN}"
            DEPENDS ${SQUAWK_PUBLIC_HEADERS} gen_hd
            WORKING_DIRECTORY ${DOXYGEN_OUTPUT_DIR}
            COMMENT "Generating doxygen docs")
    add_custom_target(doxydocs
            ALL
            DEPENDS ${DOXYGEN_INDEX_FILE} ${SQUAWK_HD}
            WORKING_DIRECTORY ${DOXYGEN_OUTPUT_DIR})

通过上述设置，构建doxydocs 将触发gen_hd，从而生成squawk.hd。如果我们构建squawk，它会发出警告：

【讨论】：