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From: "ville.voutilainen at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/95111] coroutines use-after-free with lambdas
Date: Thu, 14 May 2020 11:57:00 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95111

Ville Voutilainen <ville.voutilainen at gmail dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |ville.voutilainen at gmail=
 dot com

--- Comment #16 from Ville Voutilainen <ville.voutilainen at gmail dot com>=
 ---
(In reply to Iain Sandoe from comment #14)
> (In reply to Ville Voutilainen from comment #12)
> The idea of bringing the lambda's captures into the coro frame was what I
> originally implemented.  Richard pointed out that this is wrong when the
> lambda is mutable (see
> gcc/testsuite/g++.dg/coroutines/torture/lambda-10-mutable.C)
>=20
> so if one has
>=20
> auto X =3D [...] () -> some_coro<xxx> {};
>=20
> X must exist for the duration of the lambda coro [it was pointed out by
> Lewis that really this is only the same as saying that if you have a class
> with a member function lambda, the instance of that class has to persist =
for
> the duration of the coro].

Ah. So the work-around for this problem is to copy the capture to a local
variable, and co_return that; then the local variable is in the coro-state.
Right?=