0004158: Disable warnings on a per-line basis

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0004158

OCaml

OCaml general

public

2006-11-12 19:05

2006-11-15 12:26

Reporter

acone

Assigned To

Priority

normal

Severity

feature

Reproducibility

always

Status

acknowledged

Resolution

open

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Fixed in Version

Summary

0004158: Disable warnings on a per-line basis

Description

If I do this in ocaml, I get a warning:

type t = Foo of int | Bar of string

let list_of_all_foos = [Foo 1; Foo 2; Foo 3]

let _ =
  List.map
    (fun (Foo x) -> x)
    list_of_all_foos

The warning, of course, is that the pattern match is incomplete. But it happens all the time that I *know* which constructor some value has, and an exhaustive match would need to have a catch-all case like
| _ -> failwith "shouldn't get here"

So I have three options, none of them satisfying:
1) Write the concise version above, and accept that I'll get a crapload of warnings.
2) Write the concise version above, and disable incomplete-match warnings. This mutilates type safety, which sucks.
3) Do the more pedantic, complete match, which makes code suprisingly unreadable (and in reality, no safer).

So I want to keep the warnings on in general, but disable them for lines where I know what I'm doing. I should be able to do this in code, something like this:

let _ =
  List.map
    (fun (Foo x) -> x) {\nowarn P}
     list_of_all_foos

or maybe for a whole block of code:

DisableWarning p;;

let _ =
  List.map
    (fun (Foo x) -> x) {\nowarn P}
    list_of_all_foos

EnableWarning p;;

I realize this is a weird thing to ask for, as it mixes a hackerish compiler directive into the language. But I can't think of any other way to do this.

Issue History
Date Modified	Username	Field	Change
2006-11-12 19:05	acone	New Issue
2006-11-15 12:26	doligez	Status	new => acknowledged

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