From: Eli Zaretskii <eliz@gnu.org>
To: Philipp Stephani <p.stephani2@gmail.com>
Cc: alan@idiocy.org, emacs-devel@gnu.org, raman@google.com
Subject: Re: san_ignore_object not found at link time
Date: Sat, 01 Aug 2020 21:32:26 +0300 [thread overview]
Message-ID: <83h7tmcj45.fsf@gnu.org> (raw)
In-Reply-To: <CAArVCkTD-mVrm0rN4yN7EzJo7tXhu3Gt8VJqZL2MbcyMupFpDg@mail.gmail.com> (message from Philipp Stephani on Sat, 1 Aug 2020 20:29:29 +0200)
> From: Philipp Stephani <p.stephani2@gmail.com>
> Date: Sat, 1 Aug 2020 20:29:29 +0200
> Cc: Alan Third <alan@idiocy.org>, raman <raman@google.com>,
> Emacs developers <emacs-devel@gnu.org>
>
> > alloc.c: In function 'mark_maybe_object':
> > alloc.c:4641:14: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
> > 4641 | void *po = (char *) ((intptr_t) (char *) XLP (obj)
> > | ^
> >
> > This is a 32-bit build --with-wide-int, in case it matters, where
> > EMACS_INT is a 64-bit data type.
>
> This is due to the unrelated commit a2323c7ccb. (I just happened to
> push both commits at the same time.)
> It looks like LISP_WORD_TAG in a wide int build is a 64-bit number, so
> that the entire expression gets widened to a 64-bit number. However,
> since it's cast back to a pointer, the value has to fit in 32 bits.
The pointer is there, you just cannot safely extract it by casting to
a narrower data type. You need to explicitly mask the MSBs by
shifting or some other bit fiddling.
next prev parent reply other threads:[~2020-08-01 18:32 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-01 14:10 san_ignore_object not found at link time T.V Raman
2020-08-01 14:37 ` Eli Zaretskii
2020-08-01 14:45 ` T.V Raman
2020-08-01 14:45 ` Eli Zaretskii
2020-08-01 15:02 ` Philipp Stephani
2020-08-01 15:38 ` Alan Third
2020-08-01 17:32 ` Philipp Stephani
2020-08-01 17:51 ` Eli Zaretskii
2020-08-01 18:02 ` Eli Zaretskii
2020-08-01 18:33 ` Philipp Stephani
2020-08-01 18:52 ` Andreas Schwab
2020-08-01 18:29 ` Philipp Stephani
2020-08-01 18:32 ` Eli Zaretskii [this message]
2020-08-01 18:35 ` Philipp Stephani
2020-08-01 19:17 ` Philipp Stephani
2020-08-01 19:21 ` Philipp Stephani
2020-08-01 19:21 ` Eli Zaretskii
2020-08-01 19:26 ` Eli Zaretskii
2020-08-01 19:40 ` Philipp Stephani
2020-08-02 16:08 ` Eli Zaretskii
2020-08-01 18:09 ` T.V Raman
2020-08-01 18:13 ` Alan Third
2020-08-01 16:43 ` T.V Raman
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