Cannot instantiate variant with inline record that has optional fields

[tsnobip]

I've noticed you can define a variant with an inline record that optional fields, but you can't instantiate it.

Example:

// this compiles
type foo = Foo({name: string, age?: int})

// Error: Some record fields are undefined: age
let foo = Foo({name: "foo"}) 

We should either forbid the creation of such a type or allow to instantiate it.

[mununki]

Quick peek, I guess type declaration for optional field record as constructor argument is needed.

https://github.com/rescript-lang/rescript-compiler/blob/master/jscomp/ml/typedecl.ml#L252:L255

I think cristianoc can fix super fast, but I'll look at it too.

[mununki]

Another quick look, then I thought we need to add more information to Record_inlined. How about adding optional_labels instead adding another representation?:

and record_representation =
  ...
  | Record_inlined of                     (* Inlined record *)
      { tag : int ; name : string; num_nonconsts : int; optional_labels : string list} (* <- here *)
  ...
  | Record_optional_labels of string list (* List of optional labels *)

[cristianoc]

Another quick look, then I thought we need to add more information to Record_inlined. How about adding optional_labels instead adding another representation?:

and record_representation =
  ...
  | Record_inlined of                     (* Inlined record *)
      { tag : int ; name : string; num_nonconsts : int; optional_labels : string list} (* <- here *)
  ...
  | Record_optional_labels of string list (* List of optional labels *)

That looks like a good way to go.
I won't be able to look at this until I finish some other things. Feel free to go ahead if you'd like.

[mununki]

Another quick look, then I thought we need to add more information to Record_inlined. How about adding optional_labels instead adding another representation?:

and record_representation =
  ...
  | Record_inlined of                     (* Inlined record *)
      { tag : int ; name : string; num_nonconsts : int; optional_labels : string list} (* <- here *)
  ...
  | Record_optional_labels of string list (* List of optional labels *)

That looks like a good way to go. I won't be able to look at this until I finish some other things. Feel free to go ahead if you'd like.

Thanks for your feedback. OK I'll take and try to fix it.

[mununki]

@tsnobip Can you try it again with master or 10.1_release?

[tsnobip]

I tried on master, it worked and generated this as expected:

// Generated by ReScript, PLEASE EDIT WITH CARE
'use strict';


var foo = /* Foo */{
  name: "foo"
};

exports.foo = foo;
/* No side effect */