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From: "law at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/103483] [12 regression] context-sensitive ranges change triggers stringop-overread
Date: Fri, 28 Jan 2022 06:38:38 +0000	[thread overview]
Message-ID: <bug-103483-4-TGfuuM8vR5@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-103483-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103483

Jeffrey A. Law <law at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |law at gcc dot gnu.org

--- Comment #19 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Just threading doesn't create nonsensical blocks out of thin air.  It may
expose nonsensical code that already existed though.  That's inherent in the
path isolating nature of the transformation.

But that's not what's going on in the example you posted.  What's going on
there is we have a memcpy where we know the source has only 3 bytes of storage,
but we *may* pass in a length of 4 for the memcpy as "mystrlen" is opaque.. 
That is precisely the kind of scenario where these warnings are supposed to
trigger.


I would strongly disagree with the recommendation not to warn because of
information deduced from conditionals on the path.  That would cripple the
warnings in precisely the case where they're the most valuable IMHO.

  parent reply	other threads:[~2022-01-28  6:38 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-30  4:27 [Bug c++/103483] New: constexpr basic_string " john at mcfarlane dot name
2021-11-30  4:39 ` [Bug c++/103483] context-sensitive ranges change " pinskia at gcc dot gnu.org
2021-11-30 12:11 ` redi at gcc dot gnu.org
2021-11-30 17:56 ` [Bug middle-end/103483] " msebor at gcc dot gnu.org
2021-11-30 18:13 ` msebor at gcc dot gnu.org
2021-11-30 22:33 ` john at mcfarlane dot name
2021-12-01 16:38 ` aldyh at gcc dot gnu.org
2021-12-01 16:53 ` redi at gcc dot gnu.org
2021-12-01 23:38 ` pinskia at gcc dot gnu.org
2021-12-01 23:44 ` pinskia at gcc dot gnu.org
2021-12-02 22:14 ` msebor at gcc dot gnu.org
2021-12-09 23:24 ` cvs-commit at gcc dot gnu.org
2021-12-10 22:10 ` jason at gcc dot gnu.org
2021-12-11  0:56 ` msebor at gcc dot gnu.org
2021-12-11 22:43 ` jason at gcc dot gnu.org
2022-01-17 22:44 ` [Bug middle-end/103483] [12 regression] " jason at gcc dot gnu.org
2022-01-17 23:10 ` amacleod at redhat dot com
2022-01-18  0:47 ` msebor at gcc dot gnu.org
2022-01-28  2:02 ` pinskia at gcc dot gnu.org
2022-01-28  5:03 ` jason at gcc dot gnu.org
2022-01-28  6:38 ` law at gcc dot gnu.org [this message]
2022-01-28  7:48 ` redi at gcc dot gnu.org
2022-01-28 15:23 ` law at gcc dot gnu.org
2022-03-09 14:11 ` rguenth at gcc dot gnu.org
2022-03-14 23:58 ` msebor at gcc dot gnu.org
2022-05-06  8:32 ` [Bug middle-end/103483] [12/13 " jakub at gcc dot gnu.org
2022-10-19  9:43 ` rguenth at gcc dot gnu.org
2023-05-08 12:23 ` [Bug middle-end/103483] [12/13/14 " rguenth at gcc dot gnu.org

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