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

[Dan Peterson]

Okay.  I sort of thought that might be the case.  I think I could work
around the whole problem if there were configuration-specific versions
of COMPILE_FLAGS... oh well.

Now I'm just working out a way to get this to compile two versions of
the library without having to list the source files in two different
places

Thanks for your help!




On Fri, Apr 20, 2012 at 3:31 PM, Fraser Hutchison
<fraser.hutchison at gmail.com> wrote:
> 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.
>> --
>>
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