mel.as inside polyvariants should warn about not using mel.string

[davesnx]

Combine mel.as in more places is indeed interesting, since would allow to idiomatically bind to JS with 0 cost.

An example of lowercasing them (a silly example)

external foo: (~arg: [ | [@mel.as "lola"] `Lola | [@mel.as "flores"] `Flores]) => unit = "asdf";

let _ = foo(~arg=`Lola);

[davesnx]

Silly me, adding [@mel.string] works with this case.

external foo:
  (
    ~arg: [@mel.string] [ | [@mel.as "lola"] `Lola | [@mel.as "flores"] `Flores]
  ) =>
  unit =
  "asdf";

let _ = foo(~arg=`Lola);

My first code should have alerted me to add mel.string.

[jchavarri]

I think it should work without mel.string too (playground).

The expected behavior should be to warn when using mel.string with poly variants. It warns when mel.as is not used, but for some reason it doesn't warn when both mel.string and mel.as are used. I opened #778 to track the inconsistencies in alerts like that (see companion tests in the issue).

[anmonteiro]

My first code should have alerted me to add mel.string.

It works without @mel.string since #722

$ melc -ppx melppx  x.ml
// Generated by Melange
'use strict';


asdf("lola");

/*  Not a pure module */