https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43622
John Maddock <john at johnmaddock dot co.uk> changed:
What |Removed |Added
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CC| |john at johnmaddock dot co.uk
--- Comment #24 from John Maddock <john at johnmaddock dot co.uk> ---
(In reply to jos...@codesourcery.com from comment #23)
> On Tue, 18 Nov 2014, glisse at gcc dot gnu.org wrote:
>
> > __float128 is still missing a specialization of numeric_limits.
>
> Fully supporting an extended type (whether floating-point, or one like
> __int128 that mostly acts like an integer type) includes (as I noted in
> one of the other past bug reports on such issues, bug 50441 (fixed))
> typeinfo, numeric_limits (maybe with associated built-in macros), I/O and
> mathematical functions in general.
>
> But you may not want libstdc++ to depend on libquadmath, which may limit
> what you can support for __float128. (The ideal would be full C support
> for the relevant parts of TS 18661 in GCC and glibc, which would give you
> library support in libc and libm that could then be used from libstdc++
> when used with glibc.)
>
> I think it would be reasonable to define built-in __FLT128_*__ macros for
> __float128 similar to those defined for other floating-point types (you'd
> then make quadmath.h use those instead of hardcoding the values directly)
> - and you could then use those macros in numeric_limits. That naming is
> in line with DTS 18661-3 defining e.g. FLT128_MANT_DIG as public names for
> macros relating to _Float128.
+1 on supporting numeric_limits.
IMO while it would be nice to provide full standard lib support, there are
levels of importance here. typeinfo was essential because the user cannot add
that support themselves. numeric_limits and iostream support come next in
importance, and of course std::whatever overloads for the <cmath> functions
would be nice but come lower down I guess.
I understand the desire to limit the dependency on libquadmath - perhaps first
class std lib support should be added to <quadmath.h> rather than <limits>,
<cmath> etc if this is an overarching concern? That said, implementating
numeric_limits for that type is trivial, and this is obviously a built in type,
not a pure library extension so there is a lot to be said for providing this
support without the need to include additional headers.
While we're opening cans of worms.... intmax_t should clearly be __int128...
just saying!
