FS-1146-scoped-nowarn RFC proposal

[Martin521]

RFC proposal for scoped nowarn.
Click here to view the latest version.
For discussions, #786 has been started.

[T-Gro]

I understand the perspective of protecting against user mistakes, by calling it an error.
But I do not like the UX for the following scenario:

• A huge project, and I want to ignore a warning in just 1 file out of many.

Would the recommendation be to use:

• --nowarn 123 on project level
• #nowarn 123 in top of the file
• immediately followed by #warnon 123 right below it ?

I am wondering if the repetitive #nowarn would be needed.
The F# compilation could be changed to allow the following pairs:

1. Valid pairs of #nowarn and #warnon
2. A pair of project level --nowarn and a file level #warnon
   And produce an error in remaining cases

[Martin521]

@T-Gro Thanks for the feedback. This RFC is still in an early phase and therefore marked draft.
My plan was to get a bit further in understanding the implications of these items on the implementation and then open a discussion thread for this RFC.
If it is ok for you I would wait with a response until then.

Edit: I think the current proposal has dealt with that concern now.

[Martin521]

So, here is a full proposal.
Feedback is appreciated. Either in the discussion #786, or per review.

[T-Gro]

Heads up:

The following section will need a rewrite showing the logic and a few samples (I assume those can be taken from tests from the implementation PR once it lands):

https://learn.microsoft.com/en-us/dotnet/fsharp/language-reference/compiler-directives#preprocessor-directives

[Martin521]

Can this PR be merged?
It is still a draft then and can still be changed, but at least we have a starting point.