Re: PR35503 - warn for restrict pointer

[Prathamesh Kulkarni <prathamesh dot kulkarni at linaro dot org>]

On 22 September 2016 at 23:15, Joseph Myers <joseph@codesourcery.com> wrote:
> On Thu, 22 Sep 2016, Prathamesh Kulkarni wrote:
>
>> Would that be acceptable ? I am not sure how to make %Z check if the
>> argument has type vec<int> *
>> since vec<int> is not really a builtin C type.
>> Could you suggest me a better solution so that the format checker will check
>> if arg has type vec<int> * instead of checking if it's just a pointer ?
>> Also for testing, should I create a testcase in g++.dg since
>> gcc.dg/format/ tests are C-only ?
>
> If it's C++-only then it would need to be in g++.dg.
>
> The way we handle GCC-specific types in checking these formats is that the
> code using these formats has to define typedefs which the format-checking
> code then looks up.  In most cases it can just look up names like
> location_t or tree, but for HOST_WIDE_INT it looks up
> __gcc_host_wide_int__ which the user must have defined as a typedef.
> Probably that's the way to go in this case: the user must do "typedef
> vec<int> __gcc_vec_int__;" or similar, and the code looks up
> __gcc_vec_int__.
Thanks for the suggestions. To keep it simple, instead of vec<int>,
I made %Z take two args: int *v, unsigned len, and prints elements in
v having length == len.
Is that OK ?

Bootstrapped+tested on x86_64-unknown-linux-gnu.
As pointed out earlier in the thread, the patch can give false positives because
it only checks whether parameters are qualified with restrict, not how
parameters
are used inside the function. For instance it warned for example 10
mentioned in n1570
under section 6.7.3.1 - "Formal definition of restrict".
Should we keep the warning in Wall or keep it in Wextra ?
The attached patch enables it with Wall.

Thanks,
Prathamesh
>
> --
> Joseph S. Myers
> joseph@codesourcery.com

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