Re: [1/2] PR 78736: New warning -Wenum-conversion

[Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org>]

On 11 July 2017 at 17:59, Prathamesh Kulkarni
<prathamesh.kulkarni@linaro.org> wrote:
> On 13 June 2017 at 01:47, Joseph Myers <joseph@codesourcery.com> wrote:
>> This is OK with one fix:
>>
>>> +C ObjC Var(warn_enum_conversion) Init(0) Warning LangEnabledBy(C Objc,Wall)
>>
>> I believe the LangEnabledBy arguments are case-sensitive, so you need to
>> have ObjC not Objc there for it to work correctly.  (*.opt parsing isn't
>> very good at detecting typos and giving errors rather than silently
>> ignoring things.)
> Hi,
> Sorry for the late response, I was on a vacation.
> The attached patch is rebased and bootstrap+tested on x86_64-unknown-linux-gnu.
> I have modified it slightly to not warn for enums with different names
> but having same value ranges.
> For eg:
> enum e1 { e1_1, e1_2 };
> enum e2 { e2_1, e2_2 };
>
> enum e1 x = e2_1;
> With this version, there would be no warning for the above assignment
> since both e1 and e2 have
> same value ranges.  Is that OK ?
>
> The patch has following fallouts in the testsuite:
>
> a) libgomp:
> I initially assume it was a false positive because I thought enum
> gomp_schedule_type
> and enum omp_sched_t have same value-ranges but it looks like omp_sched_t
> has range [1, 4] while gomp_schedule_type has range [0, 4] with one
> extra element.
> Is the warning then correct for this case ?
>
> b) libgfortran:
> i) Implicit conversion from unit_mode to file_mode
> ii) Implicit conversion from unit_sign_s to unit_sign.
> I suppose the warning is OK for these cases since unit_mode, file_mode
> have different value-ranges and similarly for unit_sign_s, unit_sign ?
>
> Also I tested the warning by compiling the kernel for x86_64 with
> allmodconifg (attached), and there
> have been quite few instances of the warning (attached). I have been
> through few cases which I don't think are false positives
> but I wonder then whether we should relegate the warning to Wextra instead ?
ping: https://gcc.gnu.org/ml/gcc-patches/2017-07/msg00514.html

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