Inconsistent behaviour of Record or Enum and mapped type

[ipva3]

🔎 Search Terms

"mapped type" "record" "enum"

🕗 Version & Regression Information

• This issue can be produced in versions >= 5.8.3 (Don't test lower versions)

⏯ Playground Link

https://www.typescriptlang.org/play/?#code/GYVwdgxgLglg9mABFApgZygMXBA6jKACwCUUI4AnAE1KhArAAoBKALkVPOoB4MKYwAcwA0iPgMEA+RAG8AUIkQUUdBrIC+Abjnq55MBmToonSlUQBeIxmyR8RU9Vr0mzbXoSHUGAKJgQALYA8gBGAFaWsgqIAILsAOQAirg+APox8cLRAEIJyWnZ8TqIAIZoiPoY7lAAngAOKIgAKsZ+gaERVrUNcMDWUG3B4QDaANYoNb3I9ShT3gP+Q2EAuu6gkLAI-faEHYNojPPsjlTcLb6LHaLiQpJsYlD8QlGKyqpI8wB0+enaunLraDwD7GHYdACyJTq+0OxnYMkQwwA0hNEAJmq1LuFluwboJEOp7niXkoVC5+t8Ur8dHIPAYoP0AIyReZg8Iw+YnNyIAD0PMQADk4AzgCUYAAbRAhEAMgIgDB0rzGRmpZldUEEXbhSHQxYHTlkMzcvmITBiyUlMDmAjxcpcZTQWkoRYYi6BEkxSJJKkZLKKbJen6FGkAnCbEEYHYcuEcQ08c4LQLXR4SO64lPPeSvMlqL4-GJ-RUM+YAJhZGqI0YwXM0vP5MXFaDgiDlhlFEqAA

💻 Code

function testFuncWithRecordReturn(): Record<string, string> {
  return {};
}
const testRecord = testFuncWithRecordReturn();

const testEnumObj = {
  A: 'QWE_A',
  B: 'QWE_B'
} as const;

type TestEnumObj = typeof testEnumObj[keyof typeof testEnumObj];

function testWithObjEnums(test: Record<TestEnumObj, string>): string {
  return test.QWE_A;
}

function testWithObjMapEnums(test: { [Key in TestEnumObj]: string }): string {
  return test.QWE_A;
}

const test1 = testWithObjEnums(testRecord); // Not fail but must
const test1_1 = testWithObjMapEnums(testRecord); // Fail and it's correct

enum TestEnum {
  A = 'QWE_A',
  B = 'QWE_B'
}

function testWithEnums(test: Record<TestEnum, string>): string {
  return test.QWE_A;
}
const test2 = testWithEnums(testRecord); // Also must fail

🙁 Actual behavior

Typescript does not fail in places with specific keys objects

🙂 Expected behavior

Typescript must shows an errors in commented places with same error as the correct one

Additional information about the issue

No response

[MartinJohns]

Duplicate of #62796.

[jcalz]

This is really a duplicate of #29698 where Record<K, V> is considered contravariant in K even though it maybe shouldn't be. Here is what I'd consider a minimal example:

declare const x: Record<string, string>;
const u: { a: string } = x; // error, as expected
const v: { [K in "a"]: string } = x; // error, as expected
const w: Record<"a", string> = x; // no error?! isn't this the same as the previous two assignments?

Playground link

I guess it is also a duplicate of #62796, but for some reason everyone in that issue is talking about noUncheckedIndexedAccess instead of the actual problem?