public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/98646] [11 Regression] A static_cast confuses -Wnonnull, causing false positives
Date: Mon, 18 Jan 2021 19:13:14 +0000	[thread overview]
Message-ID: <bug-98646-4-DVbYKFvizj@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-98646-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98646

--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I don't see how either TREE_NO_WARNING or some magic call would help.
Because the user can also write:
// PR c++/98646
// { dg-do compile }
// { dg-options "-Wnonnull" }

struct B { void foo (); };
struct D : B { void show (); };

void
D::show ()
{
  constexpr D *p = nullptr;
  if (p)
    p->foo ();
}

and that also warns and IMNSHO should not.

We should warn for:
struct B { void foo (); };
struct D : B { void show (); };

void
D::show ()
{
  constexpr D *p = nullptr;
  p->foo ();
}

So, the problem is IMHO that the warning about passing NULL to this is
misplaced, it shouldn't be done in the FEs, but later when there was at least
some chance of dead code removal.

  parent reply	other threads:[~2021-01-18 19:13 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-12 22:34 [Bug c++/98646] New: " ville.voutilainen at gmail dot com
2021-01-13  0:43 ` [Bug c++/98646] [11 Regression] " msebor at gcc dot gnu.org
2021-01-13  8:12 ` rguenth at gcc dot gnu.org
2021-01-14  2:42 ` mpolacek at gcc dot gnu.org
2021-01-14  2:43 ` mpolacek at gcc dot gnu.org
2021-01-14  3:11 ` mpolacek at gcc dot gnu.org
2021-01-14  3:23 ` mpolacek at gcc dot gnu.org
2021-01-14 11:21 ` rguenth at gcc dot gnu.org
2021-01-14 16:19 ` mpolacek at gcc dot gnu.org
2021-01-14 16:22 ` mpolacek at gcc dot gnu.org
2021-01-15  0:45 ` jakub at gcc dot gnu.org
2021-01-17  0:36 ` msebor at gcc dot gnu.org
2021-01-18 19:13 ` jakub at gcc dot gnu.org [this message]
2021-01-20  1:26 ` msebor at gcc dot gnu.org
2021-01-20 21:20 ` msebor at gcc dot gnu.org
2021-01-20 22:13 ` msebor at gcc dot gnu.org
2021-01-21  0:32 ` msebor at gcc dot gnu.org
2021-01-25 19:43 ` cvs-commit at gcc dot gnu.org
2021-01-25 19:44 ` msebor at gcc dot gnu.org

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=bug-98646-4-DVbYKFvizj@http.gcc.gnu.org/bugzilla/ \
    --to=gcc-bugzilla@gcc.gnu.org \
    --cc=gcc-bugs@gcc.gnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).