On 2018-10-13 14:38, Jonathan Cameron wrote:
> On Mon, 8 Oct 2018 20:42:41 +0000
> Peter Rosin <peda@xxxxxxxxxx> wrote:
>
>> On 2018-10-08 19:35, Gustavo A. R. Silva wrote:
>>> In preparation to enabling -Wimplicit-fallthrough, mark switch cases
>>> where we are expecting to fall through.
>>
>> The way I see it, it is pretty well marked up as is. So, this paragraph
>> is not describing the change.
>>
>>>
>>> Notice that in this particular case, I replaced "...and fall through."
>>> with a proper "fall through", which is what GCC is expecting to find.
>>
>> What is not "proper" about the existing comment? Yes yes, I *know* that
>> GCC is not very intelligent about it and requires hand-holding, but
>> blaming the existing comment for not *properly* marking an intentional
>> fall through is ... rich.
>>
>>>
>>> Addresses-Coverity-ID: 1462408 ("Missing break in switch")
>>> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
>>> ---
>>> drivers/iio/dac/dpot-dac.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/iio/dac/dpot-dac.c b/drivers/iio/dac/dpot-dac.c
>>> index a791d0a..e353946 100644
>>> --- a/drivers/iio/dac/dpot-dac.c
>>> +++ b/drivers/iio/dac/dpot-dac.c
>>> @@ -78,7 +78,7 @@ static int dpot_dac_read_raw(struct iio_dev *indio_dev,
>>
>> Adding some more context here.
>>
>> case IIO_VAL_INT:
>> /*
>> * Convert integer scale to fractional scale by
>> * setting the denominator (val2) to one...
>>> */
>>> *val2 = 1;
>>> ret = IIO_VAL_FRACTIONAL;
>>> - /* ...and fall through. */
>>> + /* fall through */
>>> case IIO_VAL_FRACTIONAL:
>>> *val *= regulator_get_voltage(dac->vref) / 1000;
>>> *val2 *= dac->max_ohms;
>>>
>>
>> Considering the above added context, I have to say that this mindless
>> change is not an improvement, as you have just destroyed the continued
>> sentence from the previous comment. You must have noticed that this
>> was the end of a continued sentence, as you even quoted it in the commit
>> message. The big question is why you did not stop to think and consider
>> the context?
>>
>> Yes, I'm annoyed by mindless changes. Especially mindless changes aimed
>> at improving readability while in fact making things less readable.
>>
>> TL;DR, if you are desperate to fix "the problem" with this fall through
>> comment, please do so in a way that preserves overall readability. And
>> it would be nice to not blame the existing code for brain damage in GCC
>> and various other static analyzers.
>>
>> Cheers,
>> Peter
> I agree with you in principle Peter and have tweaked the patch description
> to make it clearer that we are doing this to make GCC static analysis more
> helpful (suppressing a false warning is a worthwhile if you are dealing with
> lots of them).
>
> However, nice though it is to have elegant comment structure I think we
> should still have this patch in place. This effort to 'fix' these
> warnings has already identified a few places where it was wrong so
> I'm keen to see it applied by default even if it isn't perfect.
I still object. It would have been so damn easy and it does not take a whole
lot of imagination to quiet down GCC while keeping the comments readable. Just
move the "and" to the previous comment, like this.
case IIO_VAL_INT:
/*
* Convert integer scale to fractional scale by
* setting the denominator (val2) to one, and...
*/
*val2 = 1;
ret = IIO_VAL_FRACTIONAL;
/* fall through */
case IIO_VAL_FRACTIONAL:
Or add a sentence, like this (which is a bit more fun IMO)
case IIO_VAL_INT:
/*
* Convert integer scale to fractional scale by
* setting the denominator (val2) to one...
*/
*val2 = 1;
ret = IIO_VAL_FRACTIONAL;
/* ...and fall through. Say it again for GCC. */
/* fall through */
case IIO_VAL_FRACTIONAL:
Cheers,
Peter
