Optional any is typed as a required any.

[rix0rrr]

Originally reported here:

aws/aws-cdk#714

The issue is that the declaration was:

interface Permission {
    sourceAccount?: any;
}

Which got translated into the following JSII:

        {
          "name": "sourceAccount",
          "type": {
            "primitive": "any"
          }
        },

I.e., the "optional" part of it got lost.

[RomainMuller]

I found the bug's cause (compiler would not consider the declaration.questionMark, and would only report as optional the union types including null and/or undefined). This actually makes me wonder if we should treat all any as optional (aka - if the type is any, then it is optional any)?

[RomainMuller]

Well the PR #237 includes code to make any optional everywhere it is found (because that is how TypeScript thinks of it).

[eladb]

But what happens if there’s an “any” argument in the middle of a signature? Optional arguments are only allowed at the end.

[RomainMuller]

Well - optional is a type attribute, not a parameter attribute. In the general sense, it denotes nullability (and in fact, TypeScript lets you put optional arguments in any place you want).

[eladb]

[rix0rrr]

Yes, there is (somewhat) of a difference between x?: l2 and x: l2 | undefined

[RomainMuller]

That is in large parts because jsii models optional as a type attribute, and not as a parameter attribute...