cmake 之 CMakeLists.txt 中的函数是从哪里来的

我们都知道，cmake会解释执行 CMakeLists.txt 以及其他 *.cmake 脚本，

这里先给出一个“先验” 的知识点：

任何一个独立脚本或脚本函数命令的执行，都是通过 CPP 函数 RunListFile(...) 调用的

void cmMakefile::RunListFile(cmListFile const& listFile,std::string const& filenametoread,DeferCommands* defer)；

所以可以debug 版本 cmake 中，在这里打断点。

0，从简单应用示例开始

在Linux 中，

源代码： main.c

#include <stdio.h>
int main()
{printf("Hello World from Main!\n");return 0;
}

CMakeLists.txt 如下：

PROJECT(HELLO)
SET(SRC_LIST main.c)
MESSAGE(STATUS "src =" ${SRC_LIST})
MESSAGE(STATUS "This is BINARY dir " ${HELLO_BINARY_DIR})
MESSAGE(STATUS "This is SOURCE dir " ${HELLO_SOURCE_DIR})
ADD_EXECUTABLE(hello ${SRC_LIST})

配置，编译，运行：

mkdir build
cd build
cmake ..
make
./hello

效果图：

1，cmake 内置关键控制字和命令

使用 CPP 代码定义了其功能

比如，如下这些函数是哪里来的：

PROJECT(...)
SET(...)
MESSAGE(...)

         如上这些是 cmake 的内置函数命令，定义在CPP文件： 

cmake-3.29.2/Source/cmCommands.cxx 

该文件内容放在文末供参考。 

源代码文件中存在如下两个定义函数，定义了一大批 CMakeLists.txt 中可以使用的关键字和内置函数命令：

void GetScriptingCommands(cmState* state)
{state->AddFlowControlCommand("break", cmBreakCommand);state->AddFlowControlCommand("continue", cmContinueCommand);state->AddFlowControlCommand("foreach", cmForEachCommand);state->AddFlowControlCommand("function", cmFunctionCommand);state->AddFlowControlCommand("if", cmIfCommand);state->AddFlowControlCommand("macro", cmMacroCommand);state->AddFlowControlCommand("return", cmReturnCommand);state->AddFlowControlCommand("while", cmWhileCommand);state->AddFlowControlCommand("block", cmBlockCommand);state->AddBuiltinCommand("cmake_language", cmCMakeLanguageCommand);state->AddBuiltinCommand("cmake_minimum_required", cmCMakeMinimumRequired);state->AddBuiltinCommand("cmake_path", cmCMakePathCommand);...

void GetProjectCommands(cmState* state)
{state->AddBuiltinCommand("add_compile_definitions",cmAddCompileDefinitionsCommand);state->AddBuiltinCommand("add_custom_command", cmAddCustomCommandCommand);state->AddBuiltinCommand("add_custom_target", cmAddCustomTargetCommand);state->AddBuiltinCommand("add_definitions", cmAddDefinitionsCommand);state->AddBuiltinCommand("add_dependencies", cmAddDependenciesCommand);state->AddBuiltinCommand("add_executable", cmAddExecutableCommand);state->AddBuiltinCommand("add_library", cmAddLibraryCommand);state->AddBuiltinCommand("add_subdirectory", cmAddSubDirectoryCommand);state->AddBuiltinCommand("add_test", cmAddTestCommand);state->AddBuiltinCommand("build_command", cmBuildCommand);state->AddBuiltinCommand("create_test_sourcelist", cmCreateTestSourceList);state->AddBuiltinCommand("define_property", cmDefinePropertyCommand);state->AddBuiltinCommand("enable_language", cmEnableLanguageCommand);state->AddBuiltinCommand("enable_testing", cmEnableTestingCommand);...

2，用户自定义 函数命令 function

除了这些之外，其余的就是用户按照脚本语法自己定义的函数。

类似 MLIR 项目中，在 LLVM - MLIR 的编译产物中，提供了一个函数 mlir_tablegen()，于文件：

local/llvm/lib/cmake/mlir/AddMLIR.cmake

其用户自定义方式如下：

从函数名可以看出，用户自定义函数命令的关键字为 function( new_COMMAND_NAME, parameters)

3，使用macro 定义的脚本命令

除了这两类，还有一部分想 check_language()这样的命令，也是cmake 官方定义的，于如下文件中：./cmake-3.29.2/Modules/CheckLanguage.cmake

4，cmCommands.cxx 内容

/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanyingfile Copyright.txt or https://cmake.org/licensing for details.  */#include "cmCommands.h"#include <cm/memory>#include "cmAddCompileDefinitionsCommand.h"
#include "cmAddCustomCommandCommand.h"
#include "cmAddCustomTargetCommand.h"
#include "cmAddDefinitionsCommand.h"
#include "cmAddDependenciesCommand.h"
#include "cmAddExecutableCommand.h"
#include "cmAddLibraryCommand.h"
#include "cmAddSubDirectoryCommand.h"
#include "cmAddTestCommand.h"
#include "cmBlockCommand.h"
#include "cmBreakCommand.h"
#include "cmBuildCommand.h"
#include "cmCMakeLanguageCommand.h"
#include "cmCMakeMinimumRequired.h"
#include "cmCMakePathCommand.h"
#include "cmCMakePolicyCommand.h"
#include "cmConfigureFileCommand.h"
#include "cmContinueCommand.h"
#include "cmCreateTestSourceList.h"
#include "cmDefinePropertyCommand.h"
#include "cmEnableLanguageCommand.h"
#include "cmEnableTestingCommand.h"
#include "cmExecProgramCommand.h"
#include "cmExecuteProcessCommand.h"
#include "cmFileCommand.h"
#include "cmFindFileCommand.h"
#include "cmFindLibraryCommand.h"
#include "cmFindPackageCommand.h"
#include "cmFindPathCommand.h"
#include "cmFindProgramCommand.h"
#include "cmForEachCommand.h"
#include "cmFunctionCommand.h"
#include "cmGetCMakePropertyCommand.h"
#include "cmGetDirectoryPropertyCommand.h"
#include "cmGetFilenameComponentCommand.h"
#include "cmGetPropertyCommand.h"
#include "cmGetSourceFilePropertyCommand.h"
#include "cmGetTargetPropertyCommand.h"
#include "cmGetTestPropertyCommand.h"
#include "cmIfCommand.h"
#include "cmIncludeCommand.h"
#include "cmIncludeDirectoryCommand.h"
#include "cmIncludeGuardCommand.h"
#include "cmIncludeRegularExpressionCommand.h"
#include "cmInstallCommand.h"
#include "cmInstallFilesCommand.h"
#include "cmInstallTargetsCommand.h"
#include "cmLinkDirectoriesCommand.h"
#include "cmListCommand.h"
#include "cmMacroCommand.h"
#include "cmMakeDirectoryCommand.h"
#include "cmMarkAsAdvancedCommand.h"
#include "cmMathCommand.h"
#include "cmMessageCommand.h"
#include "cmOptionCommand.h"
#include "cmParseArgumentsCommand.h"
#include "cmPolicies.h"
#include "cmProjectCommand.h"
#include "cmReturnCommand.h"
#include "cmSeparateArgumentsCommand.h"
#include "cmSetCommand.h"
#include "cmSetDirectoryPropertiesCommand.h"
#include "cmSetPropertyCommand.h"
#include "cmSetSourceFilesPropertiesCommand.h"
#include "cmSetTargetPropertiesCommand.h"
#include "cmSetTestsPropertiesCommand.h"
#include "cmSiteNameCommand.h"
#include "cmState.h"
#include "cmStringCommand.h"
#include "cmSubdirCommand.h"
#include "cmTargetCompileDefinitionsCommand.h"
#include "cmTargetCompileFeaturesCommand.h"
#include "cmTargetCompileOptionsCommand.h"
#include "cmTargetIncludeDirectoriesCommand.h"
#include "cmTargetLinkLibrariesCommand.h"
#include "cmTargetLinkOptionsCommand.h"
#include "cmTargetPrecompileHeadersCommand.h"
#include "cmTargetSourcesCommand.h"
#include "cmTryCompileCommand.h"
#include "cmTryRunCommand.h"
#include "cmUnsetCommand.h"
#include "cmWhileCommand.h"#if !defined(CMAKE_BOOTSTRAP)
#  include "cmAddCompileOptionsCommand.h"
#  include "cmAddLinkOptionsCommand.h"
#  include "cmAuxSourceDirectoryCommand.h"
#  include "cmBuildNameCommand.h"
#  include "cmCMakeHostSystemInformationCommand.h"
#  include "cmExportCommand.h"
#  include "cmExportLibraryDependenciesCommand.h"
#  include "cmFLTKWrapUICommand.h"
#  include "cmFileAPICommand.h"
#  include "cmIncludeExternalMSProjectCommand.h"
#  include "cmInstallProgramsCommand.h"
#  include "cmLinkLibrariesCommand.h"
#  include "cmLoadCacheCommand.h"
#  include "cmLoadCommandCommand.h"
#  include "cmOutputRequiredFilesCommand.h"
#  include "cmQTWrapCPPCommand.h"
#  include "cmQTWrapUICommand.h"
#  include "cmRemoveCommand.h"
#  include "cmRemoveDefinitionsCommand.h"
#  include "cmSourceGroupCommand.h"
#  include "cmSubdirDependsCommand.h"
#  include "cmTargetLinkDirectoriesCommand.h"
#  include "cmUseMangledMesaCommand.h"
#  include "cmUtilitySourceCommand.h"
#  include "cmVariableRequiresCommand.h"
#  include "cmVariableWatchCommand.h"
#  include "cmWriteFileCommand.h"
#endifvoid GetScriptingCommands(cmState* state)
{state->AddFlowControlCommand("break", cmBreakCommand);state->AddFlowControlCommand("continue", cmContinueCommand);state->AddFlowControlCommand("foreach", cmForEachCommand);state->AddFlowControlCommand("function", cmFunctionCommand);state->AddFlowControlCommand("if", cmIfCommand);state->AddFlowControlCommand("macro", cmMacroCommand);state->AddFlowControlCommand("return", cmReturnCommand);state->AddFlowControlCommand("while", cmWhileCommand);state->AddFlowControlCommand("block", cmBlockCommand);state->AddBuiltinCommand("cmake_language", cmCMakeLanguageCommand);state->AddBuiltinCommand("cmake_minimum_required", cmCMakeMinimumRequired);state->AddBuiltinCommand("cmake_path", cmCMakePathCommand);state->AddBuiltinCommand("cmake_policy", cmCMakePolicyCommand);state->AddBuiltinCommand("configure_file", cmConfigureFileCommand);state->AddBuiltinCommand("execute_process", cmExecuteProcessCommand);state->AddBuiltinCommand("file", cmFileCommand);state->AddBuiltinCommand("find_file", cmFindFile);state->AddBuiltinCommand("find_library", cmFindLibrary);state->AddBuiltinCommand("find_package", cmFindPackage);state->AddBuiltinCommand("find_path", cmFindPath);state->AddBuiltinCommand("find_program", cmFindProgram);state->AddBuiltinCommand("get_cmake_property", cmGetCMakePropertyCommand);state->AddBuiltinCommand("get_directory_property",cmGetDirectoryPropertyCommand);state->AddBuiltinCommand("get_filename_component",cmGetFilenameComponentCommand);state->AddBuiltinCommand("get_property", cmGetPropertyCommand);state->AddBuiltinCommand("include", cmIncludeCommand);state->AddBuiltinCommand("include_guard", cmIncludeGuardCommand);state->AddBuiltinCommand("list", cmListCommand);state->AddBuiltinCommand("make_directory", cmMakeDirectoryCommand);state->AddBuiltinCommand("mark_as_advanced", cmMarkAsAdvancedCommand);state->AddBuiltinCommand("math", cmMathCommand);state->AddBuiltinCommand("message", cmMessageCommand);state->AddBuiltinCommand("option", cmOptionCommand);state->AddBuiltinCommand("cmake_parse_arguments", cmParseArgumentsCommand);state->AddBuiltinCommand("separate_arguments", cmSeparateArgumentsCommand);state->AddBuiltinCommand("set", cmSetCommand);state->AddBuiltinCommand("set_directory_properties",cmSetDirectoryPropertiesCommand);state->AddBuiltinCommand("set_property", cmSetPropertyCommand);state->AddBuiltinCommand("site_name", cmSiteNameCommand);state->AddBuiltinCommand("string", cmStringCommand);state->AddBuiltinCommand("unset", cmUnsetCommand);state->AddUnexpectedFlowControlCommand("else","An ELSE command was found outside of a proper ""IF ENDIF structure. Or its arguments did not match ""the opening IF command.");state->AddUnexpectedFlowControlCommand("elseif","An ELSEIF command was found outside of a proper ""IF ENDIF structure.");state->AddUnexpectedFlowControlCommand("endforeach","An ENDFOREACH command was found outside of a proper ""FOREACH ENDFOREACH structure. Or its arguments did ""not match the opening FOREACH command.");state->AddUnexpectedFlowControlCommand("endfunction","An ENDFUNCTION command was found outside of a proper ""FUNCTION ENDFUNCTION structure. Or its arguments did not ""match the opening FUNCTION command.");state->AddUnexpectedFlowControlCommand("endif","An ENDIF command was found outside of a proper ""IF ENDIF structure. Or its arguments did not match ""the opening IF command.");state->AddUnexpectedFlowControlCommand("endmacro","An ENDMACRO command was found outside of a proper ""MACRO ENDMACRO structure. Or its arguments did not ""match the opening MACRO command.");state->AddUnexpectedFlowControlCommand("endwhile","An ENDWHILE command was found outside of a proper ""WHILE ENDWHILE structure. Or its arguments did not ""match the opening WHILE command.");state->AddUnexpectedFlowControlCommand("endblock","An ENDBLOCK command was found outside of a proper ""BLOCK ENDBLOCK structure.");#if !defined(CMAKE_BOOTSTRAP)state->AddBuiltinCommand("cmake_host_system_information",cmCMakeHostSystemInformationCommand);state->AddBuiltinCommand("load_cache", cmLoadCacheCommand);state->AddBuiltinCommand("remove", cmRemoveCommand);state->AddBuiltinCommand("variable_watch", cmVariableWatchCommand);state->AddBuiltinCommand("write_file", cmWriteFileCommand);state->AddDisallowedCommand("build_name", cmBuildNameCommand, cmPolicies::CMP0036,"The build_name command should not be called; see CMP0036.");state->AddDisallowedCommand("use_mangled_mesa", cmUseMangledMesaCommand, cmPolicies::CMP0030,"The use_mangled_mesa command should not be called; see CMP0030.");state->AddDisallowedCommand("exec_program", cmExecProgramCommand,cmPolicies::CMP0153,"The exec_program command should not be called; ""see CMP0153. Use execute_process() instead.","Use execute_process() instead.");#endif
}void GetProjectCommands(cmState* state)
{state->AddBuiltinCommand("add_compile_definitions",cmAddCompileDefinitionsCommand);state->AddBuiltinCommand("add_custom_command", cmAddCustomCommandCommand);state->AddBuiltinCommand("add_custom_target", cmAddCustomTargetCommand);state->AddBuiltinCommand("add_definitions", cmAddDefinitionsCommand);state->AddBuiltinCommand("add_dependencies", cmAddDependenciesCommand);state->AddBuiltinCommand("add_executable", cmAddExecutableCommand);state->AddBuiltinCommand("add_library", cmAddLibraryCommand);state->AddBuiltinCommand("add_subdirectory", cmAddSubDirectoryCommand);state->AddBuiltinCommand("add_test", cmAddTestCommand);state->AddBuiltinCommand("build_command", cmBuildCommand);state->AddBuiltinCommand("create_test_sourcelist", cmCreateTestSourceList);state->AddBuiltinCommand("define_property", cmDefinePropertyCommand);state->AddBuiltinCommand("enable_language", cmEnableLanguageCommand);state->AddBuiltinCommand("enable_testing", cmEnableTestingCommand);state->AddBuiltinCommand("get_source_file_property",cmGetSourceFilePropertyCommand);state->AddBuiltinCommand("get_target_property", cmGetTargetPropertyCommand);state->AddBuiltinCommand("get_test_property", cmGetTestPropertyCommand);state->AddBuiltinCommand("include_directories", cmIncludeDirectoryCommand);state->AddBuiltinCommand("include_regular_expression",cmIncludeRegularExpressionCommand);state->AddBuiltinCommand("install", cmInstallCommand);state->AddBuiltinCommand("install_files", cmInstallFilesCommand);state->AddBuiltinCommand("install_targets", cmInstallTargetsCommand);state->AddBuiltinCommand("link_directories", cmLinkDirectoriesCommand);state->AddBuiltinCommand("project", cmProjectCommand);state->AddBuiltinCommand("set_source_files_properties",cmSetSourceFilesPropertiesCommand);state->AddBuiltinCommand("set_target_properties",cmSetTargetPropertiesCommand);state->AddBuiltinCommand("set_tests_properties",cmSetTestsPropertiesCommand);state->AddBuiltinCommand("subdirs", cmSubdirCommand);state->AddBuiltinCommand("target_compile_definitions",cmTargetCompileDefinitionsCommand);state->AddBuiltinCommand("target_compile_features",cmTargetCompileFeaturesCommand);state->AddBuiltinCommand("target_compile_options",cmTargetCompileOptionsCommand);state->AddBuiltinCommand("target_include_directories",cmTargetIncludeDirectoriesCommand);state->AddBuiltinCommand("target_link_libraries",cmTargetLinkLibrariesCommand);state->AddBuiltinCommand("target_link_options", cmTargetLinkOptionsCommand);state->AddBuiltinCommand("target_sources", cmTargetSourcesCommand);state->AddBuiltinCommand("try_compile", cmTryCompileCommand);state->AddBuiltinCommand("try_run", cmTryRunCommand);state->AddBuiltinCommand("target_precompile_headers",cmTargetPrecompileHeadersCommand);#if !defined(CMAKE_BOOTSTRAP)state->AddBuiltinCommand("add_compile_options", cmAddCompileOptionsCommand);state->AddBuiltinCommand("aux_source_directory",cmAuxSourceDirectoryCommand);state->AddBuiltinCommand("export", cmExportCommand);state->AddBuiltinCommand("fltk_wrap_ui", cmFLTKWrapUICommand);state->AddBuiltinCommand("include_external_msproject",cmIncludeExternalMSProjectCommand);state->AddBuiltinCommand("install_programs", cmInstallProgramsCommand);state->AddBuiltinCommand("add_link_options", cmAddLinkOptionsCommand);state->AddBuiltinCommand("link_libraries", cmLinkLibrariesCommand);state->AddBuiltinCommand("target_link_directories",cmTargetLinkDirectoriesCommand);state->AddBuiltinCommand("qt_wrap_cpp", cmQTWrapCPPCommand);state->AddBuiltinCommand("qt_wrap_ui", cmQTWrapUICommand);state->AddBuiltinCommand("remove_definitions", cmRemoveDefinitionsCommand);state->AddBuiltinCommand("source_group", cmSourceGroupCommand);state->AddBuiltinCommand("cmake_file_api", cmFileAPICommand);state->AddDisallowedCommand("export_library_dependencies", cmExportLibraryDependenciesCommand,cmPolicies::CMP0033,"The export_library_dependencies command should not be called; ""see CMP0033.");state->AddDisallowedCommand("load_command", cmLoadCommandCommand, cmPolicies::CMP0031,"The load_command command should not be called; see CMP0031.");state->AddDisallowedCommand("output_required_files", cmOutputRequiredFilesCommand, cmPolicies::CMP0032,"The output_required_files command should not be called; see CMP0032.");state->AddDisallowedCommand("subdir_depends", cmSubdirDependsCommand, cmPolicies::CMP0029,"The subdir_depends command should not be called; see CMP0029.");state->AddDisallowedCommand("utility_source", cmUtilitySourceCommand, cmPolicies::CMP0034,"The utility_source command should not be called; see CMP0034.");state->AddDisallowedCommand("variable_requires", cmVariableRequiresCommand, cmPolicies::CMP0035,"The variable_requires command should not be called; see CMP0035.");
#endif
}void GetProjectCommandsInScriptMode(cmState* state)
{
#define CM_UNEXPECTED_PROJECT_COMMAND(NAME)                                   \state->AddUnexpectedCommand(NAME, "command is not scriptable")CM_UNEXPECTED_PROJECT_COMMAND("add_compile_options");CM_UNEXPECTED_PROJECT_COMMAND("add_custom_command");CM_UNEXPECTED_PROJECT_COMMAND("add_custom_target");CM_UNEXPECTED_PROJECT_COMMAND("add_definitions");CM_UNEXPECTED_PROJECT_COMMAND("add_dependencies");CM_UNEXPECTED_PROJECT_COMMAND("add_executable");CM_UNEXPECTED_PROJECT_COMMAND("add_library");CM_UNEXPECTED_PROJECT_COMMAND("add_subdirectory");CM_UNEXPECTED_PROJECT_COMMAND("add_test");CM_UNEXPECTED_PROJECT_COMMAND("aux_source_directory");CM_UNEXPECTED_PROJECT_COMMAND("build_command");CM_UNEXPECTED_PROJECT_COMMAND("cmake_file_api");CM_UNEXPECTED_PROJECT_COMMAND("create_test_sourcelist");CM_UNEXPECTED_PROJECT_COMMAND("define_property");CM_UNEXPECTED_PROJECT_COMMAND("enable_language");CM_UNEXPECTED_PROJECT_COMMAND("enable_testing");CM_UNEXPECTED_PROJECT_COMMAND("export");CM_UNEXPECTED_PROJECT_COMMAND("fltk_wrap_ui");CM_UNEXPECTED_PROJECT_COMMAND("get_source_file_property");CM_UNEXPECTED_PROJECT_COMMAND("get_target_property");CM_UNEXPECTED_PROJECT_COMMAND("get_test_property");CM_UNEXPECTED_PROJECT_COMMAND("include_directories");CM_UNEXPECTED_PROJECT_COMMAND("include_external_msproject");CM_UNEXPECTED_PROJECT_COMMAND("include_regular_expression");CM_UNEXPECTED_PROJECT_COMMAND("install");CM_UNEXPECTED_PROJECT_COMMAND("link_directories");CM_UNEXPECTED_PROJECT_COMMAND("link_libraries");CM_UNEXPECTED_PROJECT_COMMAND("project");CM_UNEXPECTED_PROJECT_COMMAND("qt_wrap_cpp");CM_UNEXPECTED_PROJECT_COMMAND("qt_wrap_ui");CM_UNEXPECTED_PROJECT_COMMAND("remove_definitions");CM_UNEXPECTED_PROJECT_COMMAND("set_source_files_properties");CM_UNEXPECTED_PROJECT_COMMAND("set_target_properties");CM_UNEXPECTED_PROJECT_COMMAND("set_tests_properties");CM_UNEXPECTED_PROJECT_COMMAND("source_group");CM_UNEXPECTED_PROJECT_COMMAND("target_compile_definitions");CM_UNEXPECTED_PROJECT_COMMAND("target_compile_features");CM_UNEXPECTED_PROJECT_COMMAND("target_compile_options");CM_UNEXPECTED_PROJECT_COMMAND("target_include_directories");CM_UNEXPECTED_PROJECT_COMMAND("target_link_libraries");CM_UNEXPECTED_PROJECT_COMMAND("target_sources");CM_UNEXPECTED_PROJECT_COMMAND("try_compile");CM_UNEXPECTED_PROJECT_COMMAND("try_run");// deprecated commandsCM_UNEXPECTED_PROJECT_COMMAND("export_library_dependencies");CM_UNEXPECTED_PROJECT_COMMAND("load_command");CM_UNEXPECTED_PROJECT_COMMAND("output_required_files");CM_UNEXPECTED_PROJECT_COMMAND("subdir_depends");CM_UNEXPECTED_PROJECT_COMMAND("utility_source");CM_UNEXPECTED_PROJECT_COMMAND("variable_requires");#undef CM_UNEXPECTED_PROJECT_COMMAND
}