Document nowarn options

[matthughes]

Compiler version

3.3.0

Problem

@nowarn annotation allows developers to ignore certain warnings from the compiler in a lexical scope. You can ignore either using compiler message or some "cat"egory. Grepping through the dotty source, I see deprecation and unchecked as options. Is there a category for unused with 3.3.0? I tried using "unused" but compiler doesn't recognize that. It would be great if scala binary could enumerate what these values are.

[som-snytt]

scalac -Wconf:help

It would be handy if compiler options were automatically documented (in an online page, as has been semi-attempted) and also if help text for helpful options were also auto-documented.

I guess this issue will be moved to discussions, where it will be "discussed to death", i.e., ignored.

[matthughes]

That is helpful thanks, but it seems to be missing "unused" right?

[som-snytt]

There is no "unused" category in Scala 3, so it is missing in that sense.

      case "cat" => conf match
        case "deprecation" => Right(Deprecated)
        case "feature"     => Right(Feature)
        case "unchecked"   => Right(Unchecked)

Perhaps it would be deemed useful as a coarse-grained category?

Or, messages could embed their "suppression code", use -Wconf:msg=NO_FOO:s to suppress this message.

The special token is arbitrary, but easier to cut/paste than natural language text.

[matthughes]

Or, messages could embed their "suppression code", use -Wconf:msg=NO_FOO:s to suppress this message.

I like that idea. Wasn't there a movement to ensure every compiler message had a unique error code so community could create pages better explaining error conditions, ways to fix, etc?

[som-snytt]

The warnings were implemented for a master's project, and error IDs would be PhD level.

It would be an obvious win for these finicky lints, since one could spend a lot of time trying to silence them.

  - Message id: id=E129
    The message id is printed with the warning.