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From: "de34 at live dot cn" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/113522] std::swap cannot be called with explicit template argument std::array<int,3>
Date: Thu, 25 Jan 2024 08:37:49 +0000 [thread overview]
Message-ID: <bug-113522-4-DCRcOgRk7N@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-113522-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113522
Jiang An <de34 at live dot cn> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |de34 at live dot cn
--- Comment #4 from Jiang An <de34 at live dot cn> ---
std::swap is not supposed to be called with explicitly specified template
arguments.
If the template arguments are not explicitly specified for std::swap, the
correct overloads will be selected if you include currect headers, even when
not all standard headers that declare std::swap overloads are included (the
shape of overload set is unspecified in such cases).
However, if you explicitly specify template arguments, there may be unintended
(likely incorrect) overloads whose template arguments are no longer
underdeduced to be selected. And then undesired implicit conversion can be
trigged during overload resolution, which can make your program ill-formed.
(In reply to Jonathan Wakely from comment #1)
> This is silly code and there is no reason to support it.
Hmm... currently it's specified in [algorithms.requirements] that
> The well-formedness and behavior of a call to an algorithm with an explicitly-specified template argument list is unspecified, except where explicitly stated otherwise.
(Added by P0896R4 and amended by LWG3419.)
Should open an LWG issue to specify similar things for std::swap?
next prev parent reply other threads:[~2024-01-25 8:37 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-20 9:22 [Bug libstdc++/113522] New: " fchelnokov at gmail dot com
2024-01-20 9:27 ` [Bug libstdc++/113522] " redi at gcc dot gnu.org
2024-01-20 9:34 ` pinskia at gcc dot gnu.org
2024-01-20 9:35 ` pinskia at gcc dot gnu.org
2024-01-25 8:37 ` de34 at live dot cn [this message]
2024-01-25 9:38 ` redi at gcc dot gnu.org
2024-01-25 9:44 ` redi at gcc dot gnu.org
2024-01-25 9:48 ` pinskia at gcc dot gnu.org
2024-01-30 12:01 ` redi at gcc dot gnu.org
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