Discriminating unions based on enum seem to bug out depending on the size of the enum

[mdaobt]

🔎 Search Terms

The issue seems that the function getMe() is not able to deal with discriminating unions.

However, it stops if I trim the enum and reduce the amount of values. Try removing everything after AA and the issue disappears.

It looks like a very convoluted example, but we really want this to work in our project.

My question is, why is the problem occurring?

🕗 Version & Regression Information

• This changed between versions 5.5.4 and 5.6.3
• This changed in commit or PR (I have no idea)
• This is the behavior in every version I tried, and I reviewed the FAQ for entries about (I have no idea)
• I was unable to test this on prior versions because it seems to be happening even now

⏯ Playground Link

Link can be found here

💻 Code

export enum EquipmentType {
  A,
  B,
  C,
  D,
  E,
  F,
  G,
  H,
  J,
  K,
  L,
  M,
  N,
  O,
  P,
  R,
  Q,
  W,
  Z,
  AA,
  AB,
  AC,
  AD,
  AE,
  AF,
  AG,
  AH,
}

export type AssetCommonData<
  T extends EquipmentType = EquipmentType
> = {
  equipmentType: T;
};

export type A = AssetCommonData & {
  equipmentType: typeof EquipmentType.A;
};

export type B = AssetCommonData & {
  equipmentType: typeof EquipmentType.B;
};

export type C = AssetCommonData & {
  equipmentType: typeof EquipmentType.C;
};


export type D = AssetCommonData & {
  equipmentType: typeof EquipmentType.D;
};

export type E = AssetCommonData & {
  equipmentType: typeof EquipmentType.E;
};

export type F = AssetCommonData & {
  equipmentType: typeof EquipmentType.F;
};

type SpecificAssetData = A | B| C | D | E |F;

type AssetData = SpecificAssetData | AssetCommonData<Exclude<EquipmentType, SpecificAssetData['equipmentType']>>;

const getMe = (equipmentType: EquipmentType): AssetData => {
    return {
        equipmentType,
    };
}

🙁 Actual behavior

Typecheck on getMe() is failing . If you remove everything after AA, the issue disappears. As if the size of the original enum affects what Typescript does.

🙂 Expected behavior

getMe() should not be failing.

Additional information about the issue

Playground link: https://www.typescriptlang.org/play/?#code/FAUwHgDg9gTgLgAhAOwK4FsEFECOqCWE6KcAKgJ4QgIDewCCAggDT0IBCrDAwlwgCJ8sfAGJ8A4nwASfAFJ8A0nwAyfALJ8AcnwDyfAAp8ASnwCKfAOp8AWn0Ys2jTo96PBj4Y7GPJjmcABfYFBIWEQ4SmpGAGdokDhuKHR0KGR+AEM4dIAeNlIkMDgUABNo7DxCYmQySIQAXnKCIhIKKmAAPnraNhAK5urWkAAuBFIAbkCJkOh4BAiqJi6YuISklLTM9IQAMm6GXqaqmqoR+ZAoADNGypbIgDpGCYCp8Bnw2vYl2PjE5NSMrI7PZIPpHQanSKXa79Y4gO7sJ4vUKzM4IbhfFa-dYAra7Oj7UG3E5zSFXXCHIlw7iI4LTMIkhb8DE-Nb-TZA-EgikDSIQqhQ8k3HlUO78Gl0lG1LDM1Z-DaAvE9QnC4YM85k5Wwu5YcWvemokQyrFshXAg5C2F89XQsH3ETi1EAZSoAGN8Bd8C7lvEcUsEAAfDiB9GBpmB6X++3BVHeuC+hrOkBuj1e75x9mB2PG+U5LBgF0AG1QxRA2UFMMGzAQieTntjOIA2gByc0VyJNgC67XaUxdqWiiAA5vE1NQGgAKVu24nl6cgACUI3r7LqnU5DBg8VQMGQwIY+65FsrbAYz0CQA

[MartinJohns]

• This changed between versions 5.5.4 and 5.6.3

What makes you think so? The playground shows no difference between those two versions.

Duplicate of #43283. Amount of elements in a union is (intentionally) limited.

[mdaobt]

Ah ! I can see why it was confusing. I was just filling out the template. I tested only in 2 versions.