在CMake中添加全局编译标志 [英] Adding global compile flags in CMake

问题描述

我正在编辑别人制作的CMakeLists.txt文件。我试图摆脱编译项目时生成的一些警告。

I am editing a CMakeLists.txt file made by someone else. I'm trying to get rid of some of the warnings generated when compiling the project.

通常我只添加 set（CMAKE_CXX_FLAGS $ {CMAKE_CXX_FLAGS } $ {MY_FLAGS}）加上我需要添加的任何标志，效果很好，但是对于此项目，它只是无法正常工作。警告仍然出现。我尝试了几种其他方法，但是什么也没做。

Normally I just add set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${MY_FLAGS}") with whatever flags I need to add, and it works fine, but for this project, it's just not working. The warnings still appear. I tried a couple alternative methods, but nothing.

是什么引起了问题？

cmake_minimum_required(VERSION 3.1)
project(PBS)

set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${CMAKE_CURRENT_SOURCE_DIR}/cmake)

option(LIBIGL_USE_STATIC_LIBRARY "Use libigl as static library" OFF)
option(LIBIGL_WITH_ANTTWEAKBAR       "Use AntTweakBar"    OFF)
option(LIBIGL_WITH_CGAL              "Use CGAL"           OFF)
option(LIBIGL_WITH_COMISO            "Use CoMiso"         OFF)
option(LIBIGL_WITH_CORK              "Use Cork"           OFF)
option(LIBIGL_WITH_EMBREE            "Use Embree"         OFF)
option(LIBIGL_WITH_LIM               "Use LIM"            OFF)
option(LIBIGL_WITH_MATLAB            "Use Matlab"         OFF)
option(LIBIGL_WITH_MOSEK             "Use MOSEK"          OFF)
option(LIBIGL_WITH_OPENGL            "Use OpenGL"         ON)
option(LIBIGL_WITH_OPENGL_GLFW       "Use GLFW"           ON)
option(LIBIGL_WITH_OPENGL_GLFW_IMGUI "Use ImGui"          ON)
option(LIBIGL_WITH_PNG               "Use PNG"            OFF)
option(LIBIGL_WITH_PYTHON            "Use Python"         OFF)
option(LIBIGL_WITH_TETGEN            "Use Tetgen"         OFF)
option(LIBIGL_WITH_TRIANGLE          "Use Triangle"       OFF)
option(LIBIGL_WITH_VIEWER            "Use OpenGL viewer"  ON)
option(LIBIGL_WITH_XML               "Use XML"            OFF)

if (NOT LIBIGL_FOUND)
    find_package(LIBIGL REQUIRED QUIET)
endif()

add_subdirectory(0_dummy)
add_subdirectory(1_cannonball)
add_subdirectory(2_spring)
add_subdirectory(3_spinning)
add_subdirectory(4_gyro)


# Custom commands
set( CMAKE_EXPORT_COMPILE_COMMANDS ON )
add_compile_options ( -Wno-reorder )
add_definitions ( -Wno-unknown-pragmas )
set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-sign-compare")

编辑：
我发现在其中之一中添加标志子目录适用于该子目录（例如，在 3_spinning / CMakeLists.txt 中）。没有办法全局设置标志吗？

I found out that adding the flags in one of the subdirectories works for that subdirectory (e.g. in 3_spinning/CMakeLists.txt). Is there no way of setting the flags globally?

推荐答案

结论： add_compile_options 和 add_definitions 适用于当前目录以及该命令后包含的所有包含的目录 。但是，设置 CMAKE_CXX_FLAGS 似乎仅适用于当前目录。但是不知道为什么，因为正如评论员Tsyvarev所说，它应该与前两种方法具有相同的作用域。

Conclusion: add_compile_options and add_definitions work on the current directory and all included directories that are included after the command. Setting CMAKE_CXX_FLAGS, however, seems to only work on the current directory. Not sure why however, because as commenter Tsyvarev says, it should have the same scope as the first two methods.

基本上，像这样移动行：

Basically, shifting the lines around like this:

[...]
# Custom commands
add_compile_options ( -Wno-reorder )
add_definitions ( -Wno-unknown-pragmas )
set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-sign-compare")

add_subdirectory(0_dummy)
add_subdirectory(1_cannonball)
add_subdirectory(2_spring)
add_subdirectory(3_spinning)
add_subdirectory(4_gyro)

我不再收到 -Wreorder 和 -Wunknown-pragmas 的警告，但仍然得到- Wsign-compare 警告。

I no longer get -Wreorder and -Wunknown-pragmas warnings, but I still get -Wsign-compare warnings.

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