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From: "m.cencora at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/99637] bit_cast doesn't work with padding bits and it should
Date: Wed, 26 Apr 2023 07:51:06 +0000 [thread overview]
Message-ID: <bug-99637-4-5xh1F8wtIM@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-99637-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99637
m.cencora at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |m.cencora at gmail dot com
--- Comment #8 from m.cencora at gmail dot com ---
I think that gcc is incorrect here, because the standard says:
"Each bit of the value representation of the result is equal to the
corresponding bit in the object representation of from."
Padding bits are part of object representation, so if padding bits are properly
initialized in source object (which is the case here), the values of padding
bits should become a part of value representation of destination object.
Also when reading the proposal p0476r2 it is clearly stated that bit_cast is
suppose to be typesafe and constexpr-compatible alternative to memcpy (which by
definition copies padding bits as is).
prev parent reply other threads:[~2023-04-26 7:51 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-17 20:46 [Bug c++/99637] New: " hanicka at hanicka dot net
2021-03-17 20:58 ` [Bug c++/99637] " jakub at gcc dot gnu.org
2021-03-17 21:19 ` hanicka at hanicka dot net
2021-03-17 21:22 ` jakub at gcc dot gnu.org
2021-03-17 21:23 ` redi at gcc dot gnu.org
2021-03-18 9:12 ` redi at gcc dot gnu.org
2021-03-18 9:19 ` jakub at gcc dot gnu.org
2021-03-18 10:35 ` redi at gcc dot gnu.org
2023-04-26 7:51 ` m.cencora at gmail dot com [this message]
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