Re: [C PATCH]: Add Walloc-type to warn about insufficient size in allocations

[Martin Uecker <uecker@tugraz.at>]

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:
> > 
> > 
> > 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.
> >   

...

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

Possibly. Having it in the FE made it simple to implement and
also reliable.  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 near future though.

Martin