[CMake] IF(... MATCHES WIN32) weird behavior

[Brad King]

Filipe Sousa wrote:
> SET(arg "WIN32")
> IF("${arg}" MATCHES "WIN32")
>   MESSAGE(STATUS ":)")
> ELSE("${arg}" MATCHES "WIN32")
>   MESSAGE(STATUS ":(")
> ENDIF("${arg}" MATCHES "WIN32")
> 
> C:\_builds\testes>cmake -G"NMake Makefiles" c:\_projects\testes
> -- :(
> -- Configuring done
> -- Generating done
> -- Build files have been written to: C:/_builds/testes

This is due to an ambiguity in the interface to the IF command left from 
early CMake versions.  Read the documentation for the IF command 
carefully, and keep in mind that "WIN32" is defined as a variable on 
Windows.  Basically the left "WIN32" is getting replaced by "1" before 
comparison.  On non-windows systems or when you use WIN3 the variable is 
not defined.

-Brad