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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/113099] locale without RTTI uses dynamic_cast before gcc 13.2 or has ODR violation since gcc 13.2
Date: Sun, 24 Dec 2023 15:30:02 +0000 [thread overview]
Message-ID: <bug-113099-4-AQZHEOf2DX@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-113099-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113099
--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #8)
> (In reply to Peter Dimov from comment #7)
> > You don't necessarily need dynamic_cast because facets are always installed
> > and obtained by their exact type, not via a reference to base.
>
> Is that true? std::use_facet<X> will return a reference to a facet with
> X::id but it could actually be something derived from X. e.g. a user can
> install their own facet derived from std::ctype<char>, which overrides some
> members. Code that does std::use_facet<std::ctype<char>>(loc) will get the
> user's facet, but via reference to base.
And I guess if the user's derived facet uses virtual inheritance from
std::locale::facet, then this could break with the
static_cast<std::ctype<char>*> in libstdc++ today. Hmm.
next prev parent reply other threads:[~2023-12-24 15:30 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-20 23:41 [Bug libstdc++/113099] New: " andysem at mail dot ru
2023-12-21 8:59 ` [Bug libstdc++/113099] " rguenth at gcc dot gnu.org
2023-12-21 21:49 ` redi at gcc dot gnu.org
2023-12-23 9:37 ` andysem at mail dot ru
2023-12-23 9:39 ` andysem at mail dot ru
2023-12-24 14:44 ` redi at gcc dot gnu.org
2023-12-24 14:46 ` redi at gcc dot gnu.org
2023-12-24 15:04 ` pdimov at gmail dot com
2023-12-24 15:27 ` redi at gcc dot gnu.org
2023-12-24 15:30 ` redi at gcc dot gnu.org [this message]
2023-12-24 15:40 ` pdimov at gmail dot com
2023-12-24 16:22 ` andysem at mail dot ru
2023-12-26 12:31 ` redi at gcc dot gnu.org
2023-12-26 15:20 ` andysem at mail dot ru
2024-01-03 12:38 ` redi at gcc dot gnu.org
2024-01-03 12:43 ` redi at gcc dot gnu.org
2024-01-05 10:23 ` cvs-commit at gcc dot gnu.org
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