[Bug]: OpenAPI YAML converts strings to boolean

[kolypto]

Describe the bug

TypeSpec converts "no" enum strings to "False", which is incorrect.

This is the so-called Norway Problem:

countries:
- GB
- NO  // Becomes false

The safest way would be to use "string" quotes for enum string values that convert to a boolean, case-insensitive:

y|yes|n|no|true|false|on|off

Reproduction

This TypeSpec file:

@service({})
namespace Main;

enum Countries {
    GB: "gb",
    NO: "no",   // !!! Norway problem
}

gets compiled into this OpenAPI:

components:
  schemas:
    Countries:
      type: string
      enum:
        - gb
        - no   # !!! Becomes boolean "false", but must be a string

Playground: link

Or compile locally this way:

$ npm install @typespec/compiler @typespec/openapi3
$ tsp compile --emit @typespec/openapi3 .

Checklist

• Follow our Code of Conduct
• Check that there isn't already an issue that request the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion.
• The provided reproduction is a minimal reproducible example of the bug.

[wanlwanl]

@kolypto I try it in Playground, but it looks like want you want. Could you double confirm?

[kolypto]

@wanlwanl it looks alright, but it won't work alright :)

Indeed, the Yaml list is rendered this way:

      enum:
        - gb
        - no

However, in Yaml, this will result in this JSON: [ "gb", false ] because no in Yaml is a boolean value! :)
It should be quoted in the output:

      enum:
        - gb
        - "no"

[wanlwanl]

@kolypto Thank you for your explanation. This is indeed related to the YAML standard specifications. YAML 1.1 treats yes/no as boolean values, while YAML 1.2 does not. The issue in typespec should indeed be addressed to support YAML 1.1 properly. For now, a temporary workaround could be explicitly specifying YAML version 1.2.x doc section 1.6.8.
FYI:
https://yaml.org/spec/1.1/current.html#id864510
https://yaml.org/spec/1.2.2/#3232-scalar-formats
https://perlpunk.github.io/yaml-test-schema/schemas.html