Fix colliding enumValues exports

[duncanbeevers]

🗣️ Discussion

This work stemmed from an error encountered when using enumValues: true, and escalated from there.

🐞 The bugs

• Types of exported literals are non-exhaustive.
• Composing OpenAPI enums generates colliding variable names.

💨 Non-exhaustive types

The existing values exported when using enumValues express their type relative to the union defined in the TS schema.

// Before
export interface components {
  schemas: {
    /** @enum {string} */
    Status: "active" | "inactive";
  };
}
export const statusValues: ReadonlyArray<components["schemas"]["Status"]> = ["active", "inactive"];

Instead, if we start with an exhaustive concrete value, the union type can be derived.

// After
export const StatusValues = ["active", "inactive"] as const;
export type Status = (typeof StatusValues)[number];
export interface components {
  schemas: {
    Status: Status;
  }
}

➕ Composing OpenAPI enums generates conflicting variable names

Given the following schema composing two enum schemas, the following bad code is generated.

components:
  schemas:
    Status:
      anyOf:
        - type: string
          enum:
            - active
            - inactive
        - type: string
          enum:
            - appealed

export const statusValues: components["schemas"]["Status"] = ["active", "inactive"];
export const statusValues: components["schemas"]["Status"] = ["appealed"];

By unifying the enum member and literal string traversal + generation paths, I was able to generate non-conflicting export names.

Changes

• Preserve capitalization of named, exported enum values.
• Type exported const values as const, instead of their location within the operations or components schemas.
• Derive and export types for enum values from concrete values in const arrays.
• Use derived enum value types in operations and components schemas.
• Use non-conflicting variable names for composed OpenAPI enums (anyOf: [enum1, enum2])
• Export a type-predicate function for each enum constant.

How to Review

• There's an unhealthy behavior around composition + enum: true. Since enums aren't composable, we still generate nonsense code like ModeratedStatus: components["schemas"]["Status"] | ModeratedStatusAnyOf1; (see the node-utils options > enum case for this example. This isn't resolved by this PR, and may be entirely unresolvable.
• Helpers and consts and such are now prepended before the primary root exports; this is necessary since some schema are now derived from these const values.
• Exported const values are no longer lower-cased. This eliminated some special-case code in a couple of spots, and allowed for exporting sanitizeMemberName and using it in transformers/schema-object. That alone makes this a breaking change.
• The as const style literals may not be for everyone, though I've found them to be succinct, reliable, and versatile for composition (literal and type-level) and iteration.

Checklist

• Unit tests updated
• docs/ updated (if necessary)
• pnpm run update:examples run (only applicable for openapi-typescript)

[changeset-bot]

🦋 Changeset detected

Latest commit: 9b38b53

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
openapi-typescript	Major

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[drwpow]

Same as the other PR—would love to use this as the base for 8.x. Thank you for adding such a big improvement to the library!

This can merge into 8.x with the minor conflict resolved (apologies if I merged them out-of-order)

[duncanbeevers]

I rebased this off of main, then off of 8.x, so it might be a little squirrely, but I think I got all the right commits in there.

[drwpow]

I rebased this off of main, then off of 8.x, so it might be a little squirrely, but I think I got all the right commits in there.

Ah yeah no worries. 8.x may diverge from main for a little bit and that’s OK. But also being a major release it’s expected. Thanks again!