failed to check the equality between two union type if union type has over 20 type

[Sczlog]

Bug Report

if there is an union type contains over 20 type, it will failed to assign the data to its property with the same type, even by itself.

🔎 Search Terms

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about 4.5.2
  and I also check next and nightly version, the bug still exist

⏯ Playground Link

https://www.typescriptlang.org/play?ts=4.6.0-dev.20211208#code/C4TwDgpgBAglC8UDeVSQFxQEQy1AvgNwBQa0AQgsquBJluXkabVAMJUpn1tMllQAIpxoZsgvi0hQAoiO7YZkgQDF5teiuWsA4urFYd26QAl9dbCePQAkufo3rUAFL3szpwGk3WT04AyPv5OALI+IU4Acj6RTgDyPnFOAAo+yU4Aij4ZTgBKPrlOAMo+RU4AKj7lTgCqPjVOAGo+jU4A6j5tTgAaPt1OAJo+A04AWj6jklLQMACMPrgE-Kzk84hcGtiMS9Psa9QKWLw7AoL7GwYSJ6wy56IWWErX0ip3h1rP0Dpvm4ZOJj8DFZPlAbICHo4Qc5wfQPCDPDDsH4Qf5EVhgiCQmiIiDImjYiC4mikiDkmj0iCMmiciDcmjCiCimiyiDymjqiCamiGiDGmjWiC2miuiDumj+iCBmiRiDRmjJjtdgBXAB2AEsAPYqhDEKB6qAAH1guv1RvIJr1RrYFsNQhtRpk9qgKidOidJidNidzidnid-idISdkSdcSdySdGSduSdRSd5SdNSdjSdbSd3SdAydoxIyvVWrWTrmTtWTrYsydZydtydr1dFf1toBnobppcrctUAR-o7tqxwd7RqJ4cHUCp0dHTPjo65ydHQvTo6l2dmuYAxlqAM7AKAAMw1GqoAAoAB6YVWalWzACU5-z2vgAD5kDaAE4QYBK1-apA2xsKE8ADoyAAGhtZhmGIDcVW3KAACMAENX2PM8oAvAtbzQ+8EGfX9G3fT9vygE8SEg6DYJPEAAC9j0w9CH1wt8Py-H8-31Q5cDAxsINzARNwAC1fNUVQAaxqbDEDgM1bQ4I1BGWaQBKE0TxMvfY5ltVYZPmOTV2IKCtx3fcNX2U9MCU4SxPvG9zMEyzVK1HCX3w5iiLwxt2M2IDQPA0iSCAA

💻 Code

type A = { type: "A" };
type B = { type: "B" };
type C = { type: "C" };
type D = { type: "D" };
type E = { type: "E" };
type F = { type: "F" };
type G = { type: "G" };
type H = { type: "H" };
type I = { type: "I" };
type J = { type: "J" };
type K = { type: "K" };
type L = { type: "L" };
type M = { type: "M" };
type N = { type: "N" };
type O = { type: "O" };
type P = { type: "P" };
type Q = { type: "Q" };
type R = { type: "R" };
type S = { type: "S" };
type T = { type: "T" };
type U = { type: "U" };
type V = { type: "V" };
type W = { type: "W" };
type X = { type: "X" };
type Y = { type: "Y" };
type Z = { type: "Z" };

type A1 = { type: "A" };
type B1 = { type: "B" };
type C1 = { type: "C" };
type D1 = { type: "D" };
type E1 = { type: "E" };
type F1 = { type: "F" };
type G1 = { type: "G" };
type H1 = { type: "H" };
type I1 = { type: "I" };
type J1 = { type: "J" };
type K1 = { type: "K" };
type L1 = { type: "L" };
type M1 = { type: "M" };
type N1 = { type: "N" };
type O1 = { type: "O" };
type P1 = { type: "P" };
type Q1 = { type: "Q" };
type R1 = { type: "R" };
type S1 = { type: "S" };
type T1 = { type: "T" };
type U1 = { type: "U" };
type V1 = { type: "V" };
type W1 = { type: "W" };
type X1 = { type: "X" };
type Y1 = { type: "Y" };
type Z1 = { type: "Z" };

type union = A|B|C|D|E|F|G|H|I|J|K|L|M|N|O|P|Q|R|S|T|U|V|W|X|Y|Z;

type union1 = A1|B1|C1|D1|E1|F1|G1|H1|I1|J1|K1|L1|M1|N1|O1|P1|Q1|R1|S1|T1|U1|V1|W1|X1|Y1|Z1;

// error
const foo = (x: union1): union => {
  return {
    type: x.type,
  };
};

const bar = (x: union1): union => {
  return x;
};

const xyz = (): union => {
  return {
    type: "A",
  };
};
//error
const abc = (x: union1): union => {
  return {
    type: x.type as union["type"],
  };
};

type shrinkUnion = A | B | C | D;
type shrinkUnion1 = A1 | B1 | C1 | D1;

const foo1 = (x: shrinkUnion1): shrinkUnion => {
  return {
    type: x.type,
  };
};

const bar1 = (x: shrinkUnion1): shrinkUnion => {
  return x;
};

const xyz1 = (): union => {
  return {
    type: "A",
  };
};

const abc1 = (x: shrinkUnion1): shrinkUnion => {
  return {
    type: x.type as shrinkUnion["type"],
  };
};

🙁 Actual behavior

failed to assign union1['type'] | union['type'] to union's type

🙂 Expected behavior

it should enable the assignment;

[MartinJohns]

See #40803. Unions have a hard limit of 25. If you remove a few elements from your union it will work.

[RyanCavanaugh]

There's no hard limit on the size of a union, but a union with more than 24 constituents can't be initialized by an expression which can only be shown to satisfy the union through explicit enumeration of possible values

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.