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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/107561] [13 Regression] g++.dg/pr71488.C  and
 [g++.dg/warn/Warray-bounds-16.C -m32] regression due to -Wstringop-overflow
 problem
Date: Wed, 01 Mar 2023 15:55:37 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107561

--- Comment #20 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #16)
> (In reply to Richard Biener from comment #15)
> > where if I understand you correctly, bar () is not allowed to modify *t=
his
> > (unless I pass it an argument to it, of course), even if *this is for
> > example
>=20
> Why?  Because it is a constructor and the object isn't fully constructed =
yet
> at that point?

Yes, exactly. The object's lifetime has not started until the constructor
completes, so accessing it is only allowed in very limited ways, described =
in
[basic.life] p6. However, it looks like for a non-trivial constructor the
results are just unspecified, not undefined, see [class.cdtor] p2. Still, I
don't see how operator new could meaningfully do anything to an object under
construction if the object is in an unspecified state. And frankly, if anyb=
ody
did write an operator new like that, they deserve what they get.

Could we have a flag that says "assume operator new is not stupid"?=