CMake中的set_target_properties是否覆盖CMAKE_CXX_FLAGS？ [英] Does set_target_properties in CMake override CMAKE_CXX_FLAGS?

问题描述

在我的CMake项目的开始，我在变量CMAKE_CXX_FLAGS中设置一般编译标志，如

At the beginning of my CMake project, I'm setting general compilation flags in the variable CMAKE_CXX_FLAGS, like

set(CMAKE_CXX_FLAGS "-W -Wall ${CMAKE_CXX_FLAGS}")

特定的编译标志（存储在BUILD_FLAGS中）。我可以为此使用以下命令：

Later on, I need to append additional configuration-specific compilation flags (stored in BUILD_FLAGS). Can I use the following command for this:

set_target_properties(${TARGET} PROPERTIES COMPILE_FLAGS ${BUILD_FLAGS})

或者我必须手动添加CMAKE_CXX_FLAGS：

or do I have to add the CMAKE_CXX_FLAGS manually:

set_target_properties(${TARGET} PROPERTIES COMPILE_FLAGS "${CMAKE_CXX_FLAGS} ${BUILD_FLAGS}")

以防止CMAKE_CXX_FLAGS被BUILD_FLAGS覆盖？

to prevent CMAKE_CXX_FLAGS being overriden by BUILD_FLAGS?

推荐答案

使用第一个：

set_target_properties(${TARGET} PROPERTIES COMPILE_FLAGS ${BUILD_FLAGS})

在编译TARGET的源时，存储在BUILD_FLAGS中的标志附加在CMAKE_CXX_FLAGS之后。

The flags stored in BUILD_FLAGS are appended after CMAKE_CXX_FLAGS when compiling the sources of TARGET. The documentation hints at this, but I've just tried it to make sure.

COMPILE_FLAGS

COMPILE_FLAGS

   Additional flags to use when compiling this target's sources. 

   The COMPILE_FLAGS property sets additional compiler flags used to
   build sources within the target.  Use COMPILE_DEFINITIONS to
   pass additional preprocessor definitions.

完整的命令行将等效于：

The full command line will be the equivalent of:

${CMAKE_CXX_COMPILER} ${CMAKE_CXX_FLAGS} ${COMPILE_FLAGS} -o foo.o -c foo.cc

正如Ramon所说，你可以随时用检查，使VERBOSE = 1 。

And as Ramon said, you can always check with make VERBOSE=1.

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