[CMake] Strange behaviour with -D option

[Michael Hertling]

On 07/01/2011 12:02 PM, pellegrini wrote:
> Hello everybody,
> 
> there is a behaviour I do not understand when using cmake with -D option.
> 
> In my project I defined a few CACHE variables. One of them is GUI to 
> specify whether or not my project should be
> built with graphical library support.
> 
> So in my main CMakeLists.txt I wrote something like:
> 
> SET(GUI FALSE CACHE BOOL "do the build in GUI mode")
> PROJECT(crysfml Fortran)
> ...
> 
> When launching cmake with:
> cmake -G "NMake Makefiles" -D CMAKE_Fortran_COMPILER=ifort -D GUI=TRUE 
> ..\..\.
> 
> I always get the following message
> 
> #################################################################
> GUI VALUE =  TRUE
> -- Configuring done
> You have changed variables that require your cache to be deleted.
> Configure will be re-run and you may have to reset some variables.
> The following variables have changed:
> CMAKE_Fortran_COMPILER= ifort
> 
> -- The Fortran compiler identification is Intel
> -- Check for working Fortran compiler: 
> C:/Intel/Compiler/11.1/054/bin/ia32/ifort.exe
> -- Check for working Fortran compiler: 
> C:/Intel/Compiler/11.1/054/bin/ia32/ifort.exe  -- works
> -- Detecting Fortran compiler ABI info
> -- Detecting Fortran compiler ABI info - done
> -- Checking whether C:/Intel/Compiler/11.1/054/bin/ia32/ifort.exe 
> supports Fortran 90
> -- Checking whether C:/Intel/Compiler/11.1/054/bin/ia32/ifort.exe 
> supports Fortran 90 -- yes
> GUI VALUE = FALSE
> -- Configuring done
> -- Generating done
> -- Build files have been written to: 
> C:/Datas/Eclipse/workspace/crysfml/build/ifort_release_win
> #################################################################
> 
> and the worse it that when deleting the cache and rebuilding it, the GUI 
> variable is switched to FALSE as you can see in the two MESSAGE commands 
> I put in my code (GUI VALUE =). Though, I would tend to think that the 
> -D command should have the last word.
> 
> There should be something I completely missed.
> 
> thanks a lot
> 
> see you
> 
> Eric

FYI, see [1,2]. ATM, until 9980 is addressed, the best you can do when
changing compilers is throwing away the build tree, starting all over
with a fresh/empty one and specifying the compilers via the CC/CXX/FC
environment variables, the usually recommended way. As an alternative,
provide one build tree per set of compilers from the first. In case of
numerous -D settings, you might use CMake's -C option for convenience.

Regards,

Michael

[1] http://www.mail-archive.com/cmake@cmake.org/msg34486.html
[2] http://public.kitware.com/Bug/view.php?id=9980