Re: autoconf: feature request: test for GCC version

[Philip Prindeville]

> On Apr 13, 2011, at 3:59 PM, Eric Blake <address@hidden> wrote:
> 
> On 04/13/2011 03:49 PM, Philip Prindeville wrote:
>> It is sometimes useful to be able to detect the compiler version (as in the 
>> case of GCC 4.2 doing some fairly aggressive optimization that breaks 
>> fragile code).
> 
> Thanks for the report.
> 
>> 
>> How about something like:
>> 
>> AC_GCC_VERSION(VER, MATCHING-VERSION, [ NON-MATCHING-VERSION ])
> 
> Unfortunately, I don't think that a macro like this belongs in autoconf.
> Why not instead follow the autoconf philosophy of feature tests rather
> than version tests, and specifically compile a problematic program that
> gets miscompiled by broken compilers and changes OPTIMIZE in that case.
> For all you know, gcc 4.2 on one machine may have some vendor-specific
> patches that don't cause the same breakage that you are seeing with
> out-of-the-box gcc 4.2.  Or, fix your code to be standards-compliant so
> that undefined code doesn't trip up a valid optimization; and if gcc is
> still miscompiling your program in your eyes, then report that as a bug
> to the gcc folks (who will help you either see where your program is
> non-compliant or will fix gcc to avoid the miscompilation).
> 


Well, because I do a lot of cross-compilation and never get to actually run 
most of the programs…

-Philip