Ts-toolbelt: O.OptionalKeys<O> returns all keys in TS 3.7

[imahassle]

🐞 Bug Report

Describe the bug

O.OptionalKeys<O> is returning a set of keys that includes required keys, not just optional keys in TypeScript 3.7.3.

O.RequiredKeys<O> has a similar issue in always returning as never.

Reproduce the bug

type Test = {
  hello: string;
  world?: string;
}

// Should be "hello", but is "hello" | "world"
type TestOptionalKeys = O.OptionalKeys<Test>

// Should be "world", but is never
type TestRequiredKeys = O.RequiredKeys<Test>

Expected behavior

I expect only the set of keys in a type marked optional (?) to be returned.

Additional context

TypeScript: 3.7.3
ts-toolbelt: 4.14.0
VSCode: 1.41.0
Node.js: 12.4.0

[millsp]

Hi @imahassle,

Everything seems right on my side

type Test = {
    hello: string;
    world?: string;
}

Optional key here is "world" and
Required key here is "hello"

In your sentence, it is the other way around

type OptionalKeys = O.OptionalKeys<Test> // world
type RequiredKeys = O.RequiredKeys<Test> // hello

[imahassle]

Ah, yes I did get it flipped around.

But the issue persists locally for me:

[millsp]

Strange, I'm also on:

TypeScript: 3.7.3
ts-toolbelt: 4.14.0
VSCode: 1.41.0
Node.js: 12.4.0

Are you using VSCode? obvioulsy
If so:

• please change the ts version in the bottom right corner & back to 3.7.3
• and in any case, remove node_modules, package-lock.json, and re-install

Did this work?

[imahassle]

Nuked my node_modules and package-lock.json and re-installed, same issue.

Do my TS libraries make a difference?

Part of my tsconfig.json:

{
  "compilerOptions": {
    "target": "ES2016",
    "lib": ["dom", "ES2016", "ES2018", "es2017.object", "scripthost", "dom.iterable"]
  }
}

I'm not aware of anything else that may make a difference.

[millsp]

Found the culprit. Please enable:

"strict": true,

If you can do that for now. I'm going to investigate why this happens exactly.

Thank you for reporting this bug!

[imahassle]

Oh that worked for me! We currently don't have strict turned on for our project. I'll have to see if it breaks anything on our side 😬

Thanks for the fast response!

And thanks for this awesome project! It's super helpful. 😁

[millsp]

Thanks for the compliments! Now thanks to you, we can see there are lots of tests failing. Gotta work on it:

tst/List.ts:56:5 - error TS2322: Type '0' is not assignable to type '1'.

56     check<T.AssignUp<[1], [[2, 1], [3, 2?]]>,   [3, 2 | 1],     Test.Pass>(),
       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/List.ts:116:5 - error TS2322: Type '0' is not assignable to type '1'.

116     check<T.Either<T_EITHER, '0' | '1'>,    EITHER_T_01,    Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/List.ts:278:5 - error TS2322: Type '0' is not assignable to type '1'.

278     check<T.Intersect<T, T1, 'equals'>,     INTERSECT_T_T1_NUMBER_EQUALS,   Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/List.ts:463:5 - error TS2322: Type '0' is not assignable to type '1'.

463     check<T.Prepend<never, [4, 5]>,         never,                  Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/List.ts:551:5 - error TS2322: Type '0' is not assignable to type '1'.

551     check<T.Tail<never>,            never,          Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:59:5 - error TS2322: Type '0' is not assignable to type '1'.

59     check<O.AssignUp<O_ASSIGNUP, Os_ASSIGNUP>,    ASSIGNUP_O_Os,   Test.Pass>(),
       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:98:5 - error TS2322: Type '0' is not assignable to type '1'.

98     check<O.CompulsoryKeys<O>,  COMPULSORYKEYS_O,   Test.Pass>(),
       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:172:5 - error TS2322: Type '0' is not assignable to type '1'.

172     check<O.Either<O_EITHER, 'a' | 'b'>,            EITHER_O_AB_TRUE,       Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:267:5 - error TS2322: Type '0' is not assignable to type '1'.

267     check<O.Filter<O, string, 'extends->'>,     FILTER_O_DEFAULT,   Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:279:5 - error TS2322: Type '0' is not assignable to type '1'.

279     check<O.FilterKeys<O, string, 'extends->'>,     FILTERKEYS_O_DEFAULT,   Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:295:5 - error TS2322: Type '0' is not assignable to type '1'.

295     check<O.Has<O, 'd', string, 'extends->'>,                       0 | 1,  Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:296:5 - error TS2322: Type '0' is not assignable to type '1'.

296     check<O.Has<O, 'd', 'string0', 'equals'>,                       0,      Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:298:5 - error TS2322: Type '0' is not assignable to type '1'.

298     check<O.Has<O, 'd', undefined, 'extends->'>,                    0 | 1,  Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:299:5 - error TS2322: Type '0' is not assignable to type '1'.

299     check<O.Has<O, 'd', 'string0', 'equals'>,                       0,      Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:305:5 - error TS2322: Type '0' is not assignable to type '1'.

305     check<O.Has<O, 'a' | 'd', string, 'extends->'>,                 0 | 1,  Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:440:5 - error TS2322: Type '0' is not assignable to type '1'.

440     check<O.Merge<O1, O>,           MERGE_O1_O,         Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:579:5 - error TS2322: Type '0' is not assignable to type '1'.

579     check<O.MergeUp<O_MERGEUP, O1_MERGEUP>,             MERGEUP_O_O1,       Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:580:5 - error TS2322: Type '0' is not assignable to type '1'.

580     check<O.MergeUp<O_MERGEUP, O1_MERGEUP, 'deep'>,     MERGEUP_O_O1_DEEP,  Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:630:5 - error TS2322: Type '0' is not assignable to type '1'.

630     check<O.NonNullableKeys<O>, 'a' | 'b' | 'c' | 'f' | 'g' | 'k',    Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:672:5 - error TS2322: Type '0' is not assignable to type '1'.

672     check<O.NullableKeys<O>,    'd' | 'e' | 'h' | 'j',    Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:732:5 - error TS2322: Type '0' is not assignable to type '1'.

732     check<O.OptionalKeys<O>,    'd' | 'e' | 'h',    Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:815:5 - error TS2322: Type '0' is not assignable to type '1'.

815     check<O.PathValid<any,          ['a', 'a']>,        ['a', 'a'],         Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:815:11 - error TS2589: Type instantiation is excessively deep and possibly infinite.

815     check<O.PathValid<any,          ['a', 'a']>,        ['a', 'a'],         Test.Pass>(),
              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:819:5 - error TS2322: Type '0' is not assignable to type '1'.

819     check<O.PathValid<O_PATHVALID,  ['b', 'b', 0]>,     ['b', 'b', 0],      Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:819:11 - error TS2589: Type instantiation is excessively deep and possibly infinite.

819     check<O.PathValid<O_PATHVALID,  ['b', 'b', 0]>,     ['b', 'b', 0],      Test.Pass>(),
              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Object.ts:971:5 - error TS2322: Type '0' is not assignable to type '1'.

971     check<O.RequiredKeys<O>,    'a' | 'b' | 'c' | 'f' | 'g' | 'j' | 'k',    Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tst/Union.ts:152:5 - error TS2322: Type '0' is not assignable to type '1'.

152     check<U.Strict<{a: 0} | {b: 0}>,    {a: 0, b?: undefined} | {a?: undefined, b: 0},  Test.Pass>(),
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[imahassle]

Yup, our project isn't ready to go with strict checking, though it's a work in progress.

For now, my workaround is to resurrect the old version of OptionalKeys:

type OptionalKeys<T extends object> = { [K in keyof T]-?: {} extends Pick<T, K> ? K : never }[keyof T]

[millsp]

Ok, you can update to the latest version and:

"strictNullChecks": true

And if you still cannot enable this, good news:
Only NonNullableKeys, CompulsoryKeys & NullableKeys are affected

Cheers