[CMake] Overriding CMAKE_<LANG>_FLAGS on a per target basis for Visual Studio project generation

[Fraser Hutchison]

Hi Dan,

I don't think it's possible to set compiler flags on a 
per-configuration, per-target basis without splitting your project.

There was a very similar discussion recently [1],[2] which indicated a 
couple of options.  However the first option can't be used on a 
per-configuration basis, which I imagine you'd need since you'll be 
wanting /MTd and /MDd for debug builds.

So you're left with using add_subdirectory() along with a separate 
CMakeLists.txt for this subdirectory which defines the flags appropriate 
for its targets, and which can have entirely different flags to its parent.

Cheers,

Fraser.

[1] http://www.cmake.org/pipermail/cmake/2012-April/049927.html
[2] http://www.cmake.org/pipermail/cmake/2012-April/049938.html



On 20/04/2012 08:31, Dan Peterson wrote:
> I love cmake, but I am still a bit of a novice, so perhaps there is a
> better way to approach this problem.  I am building a library using
> cmake.  On Windows I need to be able to build two versions: one that
> links statically to the CRT (/MT) and one that links dynamically to
> the CRT (/MD).  I would like to avoid setting properties on
> directories (not sure if it would work anyway) or doing anything that
> requires me to split my project into two pieces.
>
> I know there is a general solution to the CRT linkage problem by
> setting CMAKE_<LANG>_FLAGS globally (see
> http://stackoverflow.com/questions/1618927/cmake-microsoft-visual-studio-and-monolithic-runtimes).
>   It works great, but I cannot figure out a way to accomplish the same
> thing on a per target basis.
>
> My CMakeLists.txt for this library is similar to the following:
>
>
> INCLUDE_DIRECTORIES( "${PROJECT_SOURCE_DIR}" )
>
> SET( MYLIB_SRCS
> 	foo.h
> 	bar.h
> 	baz.h
> 	foo.cpp )
>
> IF( WIN32 )
>
> 	ADD_LIBRARY( MylibMD STATIC ${MYLIB_SRCS} )
> 	ADD_LIBRARY( MylibMT STATIC ${MYLIB_SRCS} )
>
> 	# Statically link to Visual C++ CRT
> 	FOREACH( Flag_var CMAKE_CXX_FLAGS CMAKE_CXX_FLAGS_DEBUG
> CMAKE_CXX_FLAGS_RELEASE CMAKE_CXX_FLAGS_MINSIZEREL
> CMAKE_CXX_FLAGS_RELWITHDEBINFO )
> 		IF( ${Flag_var} MATCHES "/MD" )
> 			STRING( REGEX REPLACE "/MD" "/MT" "${Flag_var}MT" "${${Flag_var}}" )
> 			SET_TARGET_PROPERTIES( MylibMT PROPERTIES "${Flag_var}" "${${Flag_var}MT}" )
> 			# I also tried this
> 			# SET_PROPERTY( TARGET MylibMT PROPERTY "${Flag_var}" "${${Flag_var}MT}" )
> 		ENDIF( ${Flag_var} MATCHES "/MD" )
> 	ENDFOREACH( Flag_var )
>
> ELSE( WIN32 )
>
> 	ADD_LIBRARY( Mylib STATIC ${MYLIB_SRCS} )
>
> ENDIF( WIN32 )
>
>
> I tried adding this in with COMPILE_FLAGS and other properties.  I
> also tried multiple things like the following in place of the for
> loop:
>
>
> SET_TARGET_PROPERTIES( MylibMT
> 				PROPERTIES
> 				STATIC_LIBRARY_FLAGS_DEBUG "/MTd"
> 				STATIC_LIBRARY_FLAGS_RELEASE "/MT"
> 				STATIC_LIBRARY_FLAGS_MINSIZEREL "/MT"
> 				STATIC_LIBRARY_FLAGS_RELWITHDEBINFO "/MT" )
>
>
> I found this thread on the mailing list:
> http://www.cmake.org/pipermail/cmake/2010-August/039046.html, but
> couldn't make any use of it, unless it would work to remove all CRT
> linkage from the CMAKE_<LANG>_FLAGS and then add it back via
> COMPILE_FLAGS or something else; but COMPILE_FLAGS doesn't seem to
> have a per configuration variant.
>
> Please let me know if it is even possible to accomplish what I am
> trying to do.  Thanks.
> --
>
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ
>
> Follow this link to subscribe/unsubscribe:
> http://www.cmake.org/mailman/listinfo/cmake