Re: [Caml-list] Warning for unused variables

[Aymeric Fromherz <aymeric.fromherz@ens.fr>]

I didn't know -warn-help. That's very complete.

Indeed, I would have considered that this case was suspicious, but I
perfectly understand your point.
Thanks a lot!

On 22/02/2017 21:01, Gabriel Scherer wrote:
> Good point, I had not noticed the different in warning number.
> 
>   `ocamlc -warn-help` says:
> 
>  26 Suspicious unused variable: unused variable that is bound
>     with "let" or "as", and doesn't start with an underscore ("_")
>     character.
>  27 Innocuous unused variable: unused variable that is not bound with
>     "let" nor "as", and doesn't start with an underscore ("_")
>     character.
> 
> I agree that the distinction is somewhat arbitrary here: arguably
> variables bound in a pattern by a *let* (instead of a
> pattern-matching) could be considered "suspicous" as well. But we
> don't want to change the semantics of an existing pattern too much, as
> it tends to annoy people, so maybe it's best left as it is.
> 
> On Wed, Feb 22, 2017 at 2:59 PM, Aymeric Fromherz
> <aymeric.fromherz@ens.fr> wrote:
>> Hi,
>>
>> Trying with OCaml 4.04 on another machine, I have the same behaviour.
>> When running the ocaml interpreter with all warnings activated (-w A
>> option), a warning is raised in the first case, but it is a warning 27
>> instead of a warning 26.
>>
>> What is the difference between these two warnings? Could it be that you
>> have all warnings activated by default?
>>
>> Thanks,
>> Aymeric
>>
>> On 22/02/2017 20:43, Gabriel Scherer wrote:
>>> This would be a bug, but I cannot reproduce it on my machine, where
>>> all OCaml versions I have (including 4.02.3) raise a warning as
>>> expected.
>>>
>>> On Wed, Feb 22, 2017 at 2:21 PM, Aymeric Fromherz
>>> <aymeric.fromherz@ens.fr> wrote:
>>>> Hi,
>>>>
>>>> Using OCaml 4.02.3, I do not have a warning for unused variables when
>>>> only one of the variables in a pair is unused.
>>>> For instance, the code
>>>>
>>>> let (a,b) = (0, 42) in b;;
>>>>
>>>> raises no warning, while
>>>>
>>>> let (a,b) = (0,42) in 1;; raises the following
>>>>
>>>> Warning 26: unused variable b.
>>>> Warning 26: unused variable a.
>>>>
>>>> I would have expected a warning in the first case since a is unused.
>>>>
>>>> Warnings for single unused variables, such as let a = 42 in 1 are still
>>>> raised.
>>>>
>>>> What is the reason for this? Is this behaviour intended? How are unused
>>>> variables determined?
>>>>
>>>> Thanks in advance,
>>>> Aymeric Fromherz
>>>>
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>>
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