From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id 440B9383F421; Wed, 29 Mar 2023 18:18:55 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 440B9383F421
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1680113935;
	bh=Nwnr7M6DiqsC16HSf0OrAWmglt356BkkUWwMbOCHFAk=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=Htk0fg7sLnflg8rW6aSP+W7kl3CsCXRivNGcBt+o0akPSsDwbGusUl6jFSsQkd7jW
	 Uk9F+a2fnEfu7UHZu5jVrUM0SsyW4DImV+5sGyenVhlCjKn6x9jrdhXb/uHm0OvWjj
	 ZRFVPnhumTjNTK9ZIAExt8XgxqALmIwjEci2XzJk=
From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug analyzer/106325] -Wanalyzer-null-dereference false positive due
 to analyzer not making assumptions for  `__attribute__((nonnull))`
Date: Wed, 29 Mar 2023 18:18:51 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: analyzer
X-Bugzilla-Version: 12.1.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: cvs-commit at gcc dot gnu.org
X-Bugzilla-Status: ASSIGNED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: dmalcolm at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-106325-4-2npInbnBxa@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-106325-4@http.gcc.gnu.org/bugzilla/>
References: <bug-106325-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106325

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by David Malcolm
<dmalcolm@gcc.gnu.org>:

https://gcc.gnu.org/g:02fbda165b74179469d9eae436fed613aa6a6ebb

commit r12-9362-g02fbda165b74179469d9eae436fed613aa6a6ebb
Author: David Malcolm <dmalcolm@redhat.com>
Date:   Wed Mar 29 14:16:48 2023 -0400

    analyzer: use __attribute__((nonnull)) at top level of analysis [PR1063=
25]

    PR analyzer/106325 reports false postives from
    -Wanalyzer-null-dereference on code like this:

    __attribute__((nonnull))
    void foo_a (Foo *p)
    {
      foo_b (p);

      switch (p->type)
        {
          /* ... */
        }
    }

    where foo_b (p) has a:

      g_return_if_fail (p);

    that expands to:

      if (!p)
        {
          return;
        }

    The analyzer "sees" the comparison against NULL in foo_b, and splits the
    analysis into the NULL and not-NULL cases; later, back in foo_a,  at
      switch (p->type)
    it complains that p is NULL.

    Previously we were only using __attribute__((nonnull)) as something to
    complain about when it was violated; we weren't using it as a source of
    knowledge.

    This patch fixes things by making the analyzer respect
    __attribute__((nonnull)) at the top-level of the analysis: any such
    params are now assumed to be non-NULL, so that the analyzer assumes the
    g_return_if_fail inside foo_b doesn't fail when called from foo_a

    Doing so fixes the false positives.

    Backported from r13-4520-gdcfc7ac94dbcf6.

    gcc/analyzer/ChangeLog:
            PR analyzer/106325
            * region-model-manager.cc
            (region_model_manager::get_or_create_null_ptr): New.
            * region-model.cc (region_model::on_top_level_param): Add
            "nonnull" param and make use of it.
            (region_model::push_frame): When handling a top-level entrypoint
            to the analysis, determine which params __attribute__((nonnull))
            applies to, and pass to on_top_level_param.
            * region-model.h (region_model_manager::get_or_create_null_ptr):
            New decl.
            (region_model::on_top_level_param): Add "nonnull" param.

    gcc/testsuite/ChangeLog:
            PR analyzer/106325
            * gcc.dg/analyzer/attr-nonnull-pr106325.c: New test.
            * gcc.dg/analyzer/attribute-nonnull.c (test_6): New.
            (test_7): New.

    Signed-off-by: David Malcolm <dmalcolm@redhat.com>=