[CMake] OS/Compiler Versioning for External Libs

[Brian Hone]

Hi Brad -

I'm working on such a C program, based on the information at:

http://predef.sourceforge.net/prearch.html

Do you think it would make sense to integrate compiler version as a 
command?  It doesn't look to hard to implement a new cmCommand.  

Brian

Brad King wrote:

> Brian Hone wrote:
>
>> Now I need to set up external dependencies.  Unfortunately, we 
>> support several OS's + compilers.  Is there a right way to handle this?
>>
>> For instance, let's say I have library foo.  I need to be able to 
>> link against:
>>
>> somedir/solaris-gcc-3.2.2/lib/libfoo.so and 
>> somedir/solaris-gcc-3.2.2/inc
>> or
>> somedir/solaris-cc/lib/libfoo.so
>> or
>> somedir/linux-gcc-3.3.3/lib/libfoo.so
>> etc.
>>
>> My thinking is to try to grab the system/compiler version and put it 
>> into the link and include dirs, but I can't figure out how to get 
>> compiler version, only compiler name. Or am I thinking about this wrong?
>
>
> This approach should work pretty well, but I have not seen it done 
> before with CMake.  There is no standard way to get the compiler 
> version from CMake.  Since there is no standard flag to get the 
> version of a compiler, I usually do it by writing a small source file 
> that uses the preprocessor to get the version:
>
> #if defined(__GNUC__) && !defined(__INTEL_COMPILER)
>   printf("gcc-%d.%d.%d", __GNUC__,
>          __GNUC_MINOR__, __GNUC_PATCH_LEVEL__);
> #elif ...
> #endif
>
> Then use the TRY_RUN command to get the output of the program.
>
> I've considered creating a standard version of this kind of program to 
> include with CMake that has knowledge of many compilers, but it is not 
> a high priority right now.
>
> -Brad
>
>