On Wed, Mar 15, 2023 at 3:30 PM Alejandro Colomar via Gcc-patches <gcc-patches@gcc.gnu.org> wrote: > > Ping
-Wuse-after-free=3 was explicitly added to cover cases with a high false-positive rate. If you want to make that the default then instead merge the equality compare case back to the =2 case. But as I said elsewhere I think that -Wuse-after-free is very much too trigger happy, especially with value-uses (not accessing released memory but inspecting the old pointer value). Please consider looking at https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104075 and review the false positives reported. Also see my very recent patches from today trying to limit -Wuse-after-free by not diagnosing from late IL. Richard. > On 2/18/23 00:05, Alejandro Colomar wrote: > > Link: > > <https://inbox.sourceware.org/gcc/3098fd18-9dbf-b4e9-bae5-62ec6fea7...@opteya.com/T/> > > Link: > > <https://github.com/shadow-maint/shadow/pull/649#discussion_r1108350066> > > Cc: Andreas Schwab <sch...@linux-m68k.org> > > Cc: David Malcolm <dmalc...@redhat.com> > > Cc: Florian Weimer <fwei...@redhat.com> > > Cc: Iker Pedrosa <ipedr...@redhat.com> > > Cc: Jens Gustedt <jens.gust...@inria.fr> > > Cc: Jonathan Wakely <jwakely....@gmail.com> > > Cc: Mark Wielaard <m...@klomp.org> > > Cc: Martin Uecker <uec...@tugraz.at> > > Cc: Michael Kerrisk <mtk.manpa...@gmail.com> > > Cc: Paul Eggert <egg...@cs.ucla.edu> > > Cc: Sam James <s...@gentoo.org> > > Cc: Siddhesh Poyarekar <siddh...@gotplt.org> > > Cc: Yann Droneaud <ydrone...@opteya.com> > > Signed-off-by: Alejandro Colomar <a...@kernel.org> > > --- > > > > This is a resend of the same patch previously sent to gcc@. > > > > gcc/c-family/c.opt | 4 ++-- > > gcc/doc/invoke.texi | 2 +- > > 2 files changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt > > index c0fea56a8f5..1a3fc2c5d74 100644 > > --- a/gcc/c-family/c.opt > > +++ b/gcc/c-family/c.opt > > @@ -1411,11 +1411,11 @@ C ObjC C++ ObjC++ Joined RejectNegative UInteger > > Var(warn_unused_const_variable) > > Warn when a const variable is unused. > > > > ; Defining this option here in addition to common.opt is necessary > > -; in order for the default -Wall setting of -Wuse-after-free=2 to take > > +; in order for the default -Wall setting of -Wuse-after-free=3 to take > > ; effect. > > > > Wuse-after-free= > > -LangEnabledBy(C ObjC C++ LTO ObjC++, Wall,2,0) > > +LangEnabledBy(C ObjC C++ LTO ObjC++, Wall,3,0) > > ; in common.opt > > > > Wvariadic-macros > > diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi > > index 7b308cd3c31..d910052ce0c 100644 > > --- a/gcc/doc/invoke.texi > > +++ b/gcc/doc/invoke.texi > > @@ -4720,7 +4720,7 @@ instead of pointers. This approach obviates needing > > to adjust the stored > > pointers after reallocation. > > @end table > > > > -@option{-Wuse-after-free=2} is included in @option{-Wall}. > > +@option{-Wuse-after-free=3} is included in @option{-Wall}. > > > > @item -Wuseless-cast @r{(C++ and Objective-C++ only)} > > @opindex Wuseless-cast > > -- > <http://www.alejandro-colomar.es/> > GPG key fingerprint: A9348594CE31283A826FBDD8D57633D441E25BB5
