[CMake] cmake_check_build_system

[Christian Lang]

>>>>>> when executing a Makefile generated by cmake, one of the first actions
>>>>>> it does is to check the cmake build system (target
>>>>>> cmake_check_build_system). For some reason we want to avoid this. Is
>>>>>> this possible without changing the Makefile manually?
>>>>>>   
>>>>>>        
>>>>>>             
>>>>> The makefiles will not work correctly without that step.
>>>>> Generated header files will not work, dependencies will not stay
>>>>> up-to-date, and several other things.
>>>>>
>>>>>      
>>>>>           
>>>> Yes, I know that it is an important step in general. In our case, nothing will change as long as the generated Makefile exists. However, it is not called "Makefile", but "CMakefile". We start the build-process by "make -f CMakefile", but because of cmake_check_build_system cmake builds a new "Makefile", overwriting the existing handwritten one - and this is what we want to avoid.
>>>>    
>>>>         
>>> Why not use a forced out of source build?
>>>  
>>>       
>> We want to use CMake as an alternative possibility to build our software in addition to our current build system, where we decided to use in-source builds - so we simply do not want an out of source build. We want an in-source build with a generated Makefile called "CMakefile". If CMake does not allow this, we have to find another way. But if it does, we would like to know how.
>>     
>
> You could do this:
> Force an out of source build and write a CMakefile into the source tree with
> configure file that has one rule in it:
>
> all:
>      cd binaray_tree;  make
>
> You could use CONFIGURE_FILE to create the CMakefile in your source tree.
>
>   
Thank you. This could be a solution.
Christian