All good questions!   I have nothing to add to that list.

Simon

From: ghc-devs [mailto:[email protected]] On Behalf Of Richard 
Eisenberg
Sent: 14 December 2015 14:44
To: Эдгар Жаворонков <[email protected]>
Cc: ghc-devs <[email protected]>
Subject: Re: Warning suppression pragmas

This proposal is a good start, but it needs more fleshing out.

- What scopes are allowed to suppress over? For example, is it possible to 
suppress warnings for scopes other than a function (for example, within a case 
expression)? What about type declarations? Local declarations? In a type 
signature?

- Is there a way to control what warnings are suppressed? Presumably, a user 
would like to suppress only certain warnings in certain places.

- Your proposal contains motivation and examples. These are necessary parts of 
a proposal. But we also need a full specification of the feature, describing 
precisely the syntax (where, exactly, `SUPPRESS` is allowed) and semantics.

I hope this feedback is helpful!
Richard

On Dec 14, 2015, at 8:52 AM, Эдгар Жаворонков 
<[email protected]<mailto:[email protected]>> wrote:


Hi devs!

I edited wiki page [1] with my proposal about more than week ago. The main idea 
is that we mark functins with pragma and filter all warnings that it will 
throw. Although it is the question of bad design, i think users, who have to 
support old libraries will find this helpful.

I don't know about suppressing specific kinds of warnings. I think, that it 
would be more precise to filter them in one place instead of many.

Can someone review it? Sorry for bothering, if any

[1] - https://ghc.haskell.org/trac/ghc/wiki/Design/LocalWarningPragmas

---
С уважением,
Жаворонков Эдгар

Best regards,
Edgar A. Zhavoronkov

2015-12-03 15:16 GMT+03:00 Ben Gamari 
<[email protected]<mailto:[email protected]>>:
Эдгар Жаворонков <[email protected]<mailto:[email protected]>> 
writes:

> Hello devs!
>
> I am trying to implement some kind of local warnings suppresion and i need
> some help.
>
> I want to use a pragma to mark functions so compiler won't throw warnings
> from them. I defined my pragma in lexer, parser and added type signature in
> HsBinds.hs. And i am stuck. I don't know what to do. What should i consider
> doing further?
>
I think it would be helpful to focus on further elaborating the
specification before we move into the implementation. There are still a
number of open questions about the design that the wiki page doesn't yet
address.

For instance, you should explicitly specify,

 * What are the identifiers that appear after the `SUPPRESS` token?

 * What exactly does the pragma apply to? For instance, if I have a case
   like,

       hello :: Int -> Int
       {-# SUPPRESS some-warning #-}
       helloAgain :: Type -> AnotherType
       hello = (+1)
       helloAgain = error "42"

   or even just
       hello = (+1)
       {-# SUPPRESS another-warning #-}
       helloAgain = error "oops"

   What do you expect to happen? The behavior of the pragma in both of
   these cases should be unambiguously stated in the specification.

 * An concrete use-case motivating the change (preferably with examples
   showing how the proposed syntax would address the motivation)

I know this sounds repetitive, but the act of writing down a proposal
will help you immensely when you do move on to implementing your ideas.

Thanks for your persistence.

Cheers,

- Ben

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