[CMake] A question about cache variables

[Michael Hertling]

On 10/26/2010 08:47 PM, mina adel wrote:
> 
> 
> Hi All,
> I have a problem with cache variables in cmake.
> 
> I want to check the combiler for a certain flag -C99 flag. So, I used the 
> following statement
> CHECK_C_COMPILER_FLAG("-C99" FLAG_OK)
> 
> The problem is that we I ran cmake for the first time it said that c99 is not 
> found and set the FLAG_OK variable in CMakeCache.txt to 0.
> 
> Now, I fixed the problem =in the compiler to make it support -C99. But cmake 
> doesnot check the flag any more and just keep saying not found. This is becuase 
> the FLAG_OK is already equals  to 0 in cache file.
> 
> Is there any way to delete the cahce variable. or force cmake to check for the 
> flag every time I run it?

Rerun CMake with -UFLAG_OK or restart from within an empty build
directory or use UNSET(FLAG_OK CACHE) in your CMakeLists.txt, but
note: The purpose of caching is to avoid finding out the concerned
variables' values every time CMake runs, and the capabilities of a
compiler w.r.t. the acceptance of flags usually don't change often.

Regards,

Michael