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Re: PR other/54324: allow bootstrapping with older compilers


On Wed, Dec 12, 2012 at 2:21 AM, Steven Bosscher <stevenb.gcc@gmail.com> wrote:
> On Wed, Dec 12, 2012 at 6:07 AM, Aldy Hernandez wrote:
>> I don't know how much of this is a fool's errand, and if we want to commit
>> to supporting < GCC 3.4, but your patch suggested c++98, and GCC 3.2 claims
>> such.
>
> GCC 3.2 claims many things, but any GCC that has the old C++ parser
> has known non-conformances. IMHO we should only support GCC versions
> with the "new" C++ parser, i.e. GCC 3.4 and up.
>
>
>>    Perhaps we could even deprecate ARG_UNUSED?
>
> +1
>
>
>> 2. gcov-io.c uses __builtin_popcountll and __builtin_clzll.  Older
>>    GCC's do not have this.  For that matter, how does this even work on
>>    non-GCC systems?
>
> This'd be a bug.
>
>
>> I really don't want to spend much more time on this, but at the same time, I
>> don't want to throw away a day's work, especially if it could conceivably
>> help us with (older) non-GCC bootstrap compilers.
>
> I think the work you've done here is great, but even if you'd fix
> these issues, there is very little that can be done to avoid the same
> mistakes, or new ones, creeping back in and breaking builds with older
> compilers.
>
>
>> What are your thoughts on this?
>
> At least: Thanks for uncovering the gcov-io.c bug :-)

Yes, thanks for fixing this. The fix looks good to me.

Thanks,
Teresa

>
> Ciao!
> Steven



--
Teresa Johnson | Software Engineer | tejohnson@google.com | 408-460-2413


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