strictIndexSignatures appears to be broken since at least v11.0.0

[benjamincburns]

Per the title, it seems the strictIndexSignatures option has no effect since v11.0.0.

The below script fetches the latest JSONSchema for NPM's package.json file and attempts to generate types for it. In spite of the strictIndexSignatures: true at line 20, I still get errors like the following:

lib/types.ts:15788:3 - error TS2411: Property 'require' of type 'PackageExportsEntry | PackageExportsFallback | undefined' is not assignable to 'string' index type 'PackageExportsEntry | PackageExportsFallback'.

15788   require?: PackageExportsEntry | PackageExportsFallback;

The script in question (depends on got to fetch the schema) is here:

import { resolve as pathResolve, join as pathJoin } from "path";
import { writeFileSync } from "fs";

import got from "got";
import { compile } from "json-schema-to-typescript";
import type { JSONSchema4 } from "json-schema";

const url =
  "https://raw.githubusercontent.com/SchemaStore/schemastore/master/src/schemas/json/package.json";
const outputPath = pathJoin(pathResolve(__dirname, "..", "lib"), "package-json-types.ts");

(async function () {
  try {
    console.log(`Fetching updated JSONSchema for package.json from ${url}`);
    const schema = (await got(url).json()) as JSONSchema4;

    console.log("Converting JSONSchema to TypeScript interfaces");
    const result = await compile(schema, "PackageJson", {
      unreachableDefinitions: true,
      strictIndexSignatures: true,
    });

    console.log(`Writing interfaces to ${outputPath}`);
    writeFileSync(outputPath, result, { encoding: "utf8" });
  } catch (err) {
    console.error(err);
    process.exit(1);
  }
})();

[bcherny]

This is a dup of #299. Suggestions welcome!

[benjamincburns]

@bcherny are you sure it's strictly a duplicate of that issue? I don't see why #299 would prevent a true value for the strictIndexSignatures flag from simply tacking a | undefined onto the end of an index signature.

[benjamincburns]

To be clear, in #299 there's a broader issue where there's a conflict between the types of the defined properties and the additionalProperties type. In this case I literally just want strictIndexSignatures to do exactly what the docs say that it does and "[a]ppend all index signatures with | undefined"