On Wed, May 30, 2018 at 08:45:22AM -0500, Segher Boessenkool wrote:
> > If you need to keep g for compatibility (you do), then why not just have
> > e (long double is double)
> > g (long double when matching __ibm128, or explicit __ibm128)
> > u9__ieee128 (long double when matching __ieee128, or explicit __ieee128)
>
> "g" means __float128. Which is __ieee128. And it has to be, because
> so much code expects that already, and it will only become more. But
> "g" is demangled as __float128. Confusion galore.
Is that such a big deal? It hasn't been a problem in the past decade when
it was similarly wrong too. And, with the intent to phase out long double
as __ibm128 (at least on powerpc64le) shortly only libstdc++ and perhaps a
couple of other libraries will have this demangling glitch (and those will
have it in any case, because there will be the compatibility aliases that
will demangle as __float128). So I really don't see any advantages of
changing the __ibm128 and/or long double that is __ibm128 mangling from
g to something else. But I see severe disadvantages.
The libstdc++ changes to support both __ibm128 and __ieee128 will be very
hard themselves, there is no need to complicate it further.
Jakub
