From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20476 invoked by alias); 18 Nov 2014 23:50:57 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 20392 invoked by uid 55); 18 Nov 2014 23:50:53 -0000 From: "joseph at codesourcery dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/43622] no C++ typeinfo for __float128 Date: Tue, 18 Nov 2014 23:50:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: libstdc++ X-Bugzilla-Version: 4.5.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: enhancement X-Bugzilla-Who: joseph at codesourcery dot com X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: bkoz at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2014-11/txt/msg01784.txt.bz2 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43622 --- Comment #23 from joseph at codesourcery dot com --- 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.