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Message-ID: <5e7e4be39deeedf52496f939cb4616a1066d5e10.camel@tugraz.at>
Subject: Re: [C PATCH]: Add Walloc-type to warn about insufficient size in
 allocations
From: Martin Uecker <uecker@tugraz.at>
To: Siddhesh Poyarekar <siddhesh@gotplt.org>, gcc-patches@gcc.gnu.org
Cc: Joseph Myers <joseph@codesourcery.com>
Date: Mon, 31 Jul 2023 22:06:44 +0200
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Am Montag, dem 31.07.2023 um 15:39 -0400 schrieb Siddhesh Poyarekar:
> On 2023-07-21 07:21, Martin Uecker via Gcc-patches wrote:
> >=20
> >=20
> > This patch adds a warning for allocations with insufficient size
> > based on the "alloc_size" attribute and the type of the pointer
> > the result is assigned to. While it is theoretically legal to
> > assign to the wrong pointer type and cast it to the right type
> > later, this almost always indicates an error. Since this catches
> > common mistakes and is simple to diagnose, it is suggested to
> > add this warning.
> >  =20

...

> >=20
>=20
> Wouldn't this be much more useful in later phases with ranger feedback=
=20
> like with the warn_access warnings?  That way the comparison won't be=20
> limited to constant sizes.

Possibly. Having it in the FE made it simple to implement and
also reliable.=C2=A0 One thing I considered is also looking deeper
into the argument and detect obvious mistakes, e.g. if the
type in a sizeof is the right one. Such extensions would be
easier in the FE.

But I wouldn't mind replacing or extending this with something
smarter emitted from later phases. I probably do not have time
to work on this is myself in the=C2=A0near future though.

Martin