Re: [GSoC] Discussion of warnings and of a first patch (name-hiding)

Re: [GSoC] Discussion of warnings and of a first patch (name-hiding)

[Benjamin Priour]

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Hi Jason,

Sorry for the delayed answer, I was in my exam period!

I've almost finished the patch (PR12341
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=12341>), and wrote a testcase
to compare it against.
In it I use dejaGNU instructions of the format:
 /* { dg-warning "'C::bbb' might shadow 'B::bbb'." "" { target *-*-* }
C_shadowing_bbb } */
and run the test with:
make check-gcc-c++ RUNTESTFLAGS="-v -v --target_board=unix\{-m32,-m64\}
dg.exp=pr12341-1.C"
I get expected results on most target, except on target hppa*-*-hpux*.
I have been looking around the documentation, yet I cannot find a way to
run on that target specifically, especially considering the wildcards. How
to test GCC on a simulator <https://gcc.gnu.org/simtest-howto.html> don't
specify that target in the bottom table.
Would you have any guidance on how to do so ? I would like to debug the
test on that platform.

Otherwise, I believe it is working just fine, I put it as an enhancement to
-Wshadow. Should I send it to gcc-patches ? I wasn't sure I was supposed to
since it's still buggy, so I preferred to refrain.


>   Up to now I have considered some extra warning

> 1- Warning for NULL smart pointers dereferencing. E.g. when a smart
> > pointer is left uninitialized yet is derefe0renced.
>
> I would expect that to be covered by (enhancements to?) the existing
> -Wuninitialized or -Wmaybe-uninitialized or
> -Wanalyzer-use-of-uninitialized-value.
>

> > 3- Use after move.
>
> Hmm, it might make sense to approach this as an enhancement to the
> uninitialized warnings whereby a move makes us consider the object no
> longer initialized, much like -Wuse-after-free and
> -Wanalyzer-use-after-free.
>
> > 4- Use references or raw pointers as parameters when ownership is not
> > considered. (For general use, take T* or T& arguments rather than smart
> > pointers
> > <
> https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#f7-for-general-use-take-t-or-t-arguments-rather-than-smart-pointers
> >)
>
> This seems feasible to implement in the front-end.
>
>
I will update on these warnings and a few questions on the analyzer
tomorrow, I now got some free time back.
Benjamin

Re: [GSoC] Discussion of warnings and of a first patch (name-hiding)

[Martin Jambor]

Hello,

it feels like I have read only a small part of your conversation and so
may be missing quite some context, but...


On Wed, Mar 22 2023, Benjamin Priour via Gcc wrote:
> Hi Jason,
>
> Sorry for the delayed answer, I was in my exam period!
>
> I've almost finished the patch (PR12341
> <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=12341>), and wrote a testcase
> to compare it against.
> In it I use dejaGNU instructions of the format:
>  /* { dg-warning "'C::bbb' might shadow 'B::bbb'." "" { target *-*-* }
> C_shadowing_bbb } */
> and run the test with:
> make check-gcc-c++ RUNTESTFLAGS="-v -v --target_board=unix\{-m32,-m64\}
> dg.exp=pr12341-1.C"
> I get expected results on most target, except on target hppa*-*-hpux*.

...don't worry about hppa or hpux at this point and...

> I have been looking around the documentation, yet I cannot find a way to
> run on that target specifically, especially considering the wildcards. How
> to test GCC on a simulator <https://gcc.gnu.org/simtest-howto.html> don't
> specify that target in the bottom table.
> Would you have any guidance on how to do so ? I would like to debug the
> test on that platform.
>
> Otherwise, I believe it is working just fine, I put it as an enhancement to
> -Wshadow. Should I send it to gcc-patches ? I wasn't sure I was supposed to
> since it's still buggy, so I preferred to refrain.

...yes, if you would like to get feedback, send it to gcc-patches.
Prefix the subject with "[RFC]" if you want to point out that you are
looking for feedback and not an approval to commit.  Spell out any known
issues.  It is a good idea to CC some maintainer of the gcc component
you modify, so Jason in this case.

Thanks for your perseverance, I know it is not easy,

Martin