[cfe-dev] [PATCH]: add support for FreeBSD

Chris Lattner clattner at apple.com
Sun Oct 12 10:28:30 PDT 2008

On Oct 11, 2008, at 2:08 AM, Roman Divacky wrote:
>> I'm confused about why that would be useful.  Worst case you could
>> parse the output of 'system("uname -a")' or something, no?   
>> Presumably
>> uname is implemented in terms of some library/system call, and that
>> could just be used instead?
> there's some confusion here...
> we are talking about:
> +  Define(Defs, "__FreeBSD__", "8");

As Daniel pointed out, this one can be obtained from a dynamic check.

> +  Define(Defs, "__FreeBSD_cc_version", "800001");
> right?
> the problem is that the second number is defined only in an internal  
> freebsd
> header file or can be obtained via "gcc -E -dM dummy_file.c", the  
> __FreeBSD_cc_version
> does not correspond to anything in uname.

Ok, but what *is* that number and how does it get used?  For example,  
we always currently hardcode these values:

   DefineBuiltinMacro(Buf, "__GNUC_MINOR__=2");
   DefineBuiltinMacro(Buf, "__GNUC_PATCHLEVEL__=1");
   DefineBuiltinMacro(Buf, "__GNUC__=4");

this is us claiming to be 4.2.1.  In my mind, this is ok because code  
checking these is really almost always doing a feature check on some  
thing that 4.2.1 supports, and we plan to eventually support most of  

Is __FreeBSD_cc_version like this?  When does it change?  What other  
values has it been over time?  Is it always just '__FreeBSD__ +  


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