[CMake] 64bit linking on linux

[Bill Hoffman]

Aaron Turner wrote:

>>>
>> That is not the preferable way to do this.  As it hard codes flags into the
>> CMake file.  The way I would do it is:
>>
>> export CXXFLAGS=-m64
>> export CFLAGS=-m64
>> export LDFLAGS=-m64
>>
>> cmake ../myproject
>>
>> If those environment variables are set BEFORE you run cmake, then cmake will
>> put them into the cache correctly.
> 
> Couldn't you use the check_c_source_runs() macro to test if your
> system supports the -m64 flag?  That way you wouldn't need to require
> the user to specify it (always fraught with peril).
> 
> 
You could if you always wanted a 64 bit app.  It is really up to the 
project.

-Bill