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Limit size of union types resulting from intersection type normalization #31572

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6 changes: 6 additions & 0 deletions src/compiler/checker.ts
Original file line number Diff line number Diff line change
Expand Up @@ -9908,6 +9908,12 @@ namespace ts {
else {
// We are attempting to construct a type of the form X & (A | B) & Y. Transform this into a type of
// the form X & A & Y | X & B & Y and recursively reduce until no union type constituents remain.
// If the estimated size of the resulting union type exceeds 100000 constituents, report an error.
const size = reduceLeft(typeSet, (n, t) => n * (t.flags & TypeFlags.Union ? (<UnionType>t).types.length : 1), 1);
if (size >= 100000) {
error(currentNode, Diagnostics.Expression_produces_a_union_type_that_is_too_complex_to_represent);
return errorType;
}
const unionIndex = findIndex(typeSet, t => (t.flags & TypeFlags.Union) !== 0);
const unionType = <UnionType>typeSet[unionIndex];
result = getUnionType(map(unionType.types, t => getIntersectionType(replaceElement(typeSet, unionIndex, t))),
Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,46 @@
tests/cases/compiler/normalizedIntersectionTooComplex.ts(36,14): error TS2590: Expression produces a union type that is too complex to represent.
tests/cases/compiler/normalizedIntersectionTooComplex.ts(36,40): error TS7006: Parameter 'x' implicitly has an 'any' type.


==== tests/cases/compiler/normalizedIntersectionTooComplex.ts (2 errors) ====
// Repro from #30050

interface Obj<T> {
ref: T;
}
interface Func<T> {
(x: T): void;
}
type UnionToIntersection<U> = (U extends any ? (k: U) => void : never) extends ((k: infer I) => void) ? I : never;
type CtorOf<T> = (arg: UnionToIntersection<T>) => T;

interface Big {
"0": { common?: string; "0"?: number, ref?: Obj<Big["0"]> | Func<Big["0"]>; }
"1": { common?: string; "1"?: number, ref?: Obj<Big["1"]> | Func<Big["1"]>; }
"2": { common?: string; "2"?: number, ref?: Obj<Big["2"]> | Func<Big["2"]>; }
"3": { common?: string; "3"?: number, ref?: Obj<Big["3"]> | Func<Big["3"]>; }
"4": { common?: string; "4"?: number, ref?: Obj<Big["4"]> | Func<Big["4"]>; }
"5": { common?: string; "5"?: number, ref?: Obj<Big["5"]> | Func<Big["5"]>; }
"6": { common?: string; "6"?: number, ref?: Obj<Big["6"]> | Func<Big["6"]>; }
"7": { common?: string; "7"?: number, ref?: Obj<Big["7"]> | Func<Big["7"]>; }
"8": { common?: string; "8"?: number, ref?: Obj<Big["8"]> | Func<Big["8"]>; }
"9": { common?: string; "9"?: number, ref?: Obj<Big["9"]> | Func<Big["9"]>; }
"10": { common?: string; "10"?: number, ref?: Obj<Big["10"]> | Func<Big["10"]>; }
"11": { common?: string; "11"?: number, ref?: Obj<Big["11"]> | Func<Big["11"]>; }
"12": { common?: string; "12"?: number, ref?: Obj<Big["12"]> | Func<Big["12"]>; }
"13": { common?: string; "13"?: number, ref?: Obj<Big["13"]> | Func<Big["13"]>; }
"14": { common?: string; "14"?: number, ref?: Obj<Big["14"]> | Func<Big["14"]>; }
"15": { common?: string; "15"?: number, ref?: Obj<Big["15"]> | Func<Big["15"]>; }
"16": { common?: string; "16"?: number, ref?: Obj<Big["16"]> | Func<Big["16"]>; }
"17": { common?: string; "17"?: number, ref?: Obj<Big["17"]> | Func<Big["17"]>; }
}
declare function getCtor<T extends keyof Big>(comp: T): CtorOf<Big[T]>

declare var all: keyof Big;
const ctor = getCtor(all);
const comp = ctor({ common: "ok", ref: x => console.log(x) });
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!!! error TS2590: Expression produces a union type that is too complex to represent.
~
!!! error TS7006: Parameter 'x' implicitly has an 'any' type.

44 changes: 44 additions & 0 deletions tests/baselines/reference/normalizedIntersectionTooComplex.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,44 @@
//// [normalizedIntersectionTooComplex.ts]
// Repro from #30050

interface Obj<T> {
ref: T;
}
interface Func<T> {
(x: T): void;
}
type UnionToIntersection<U> = (U extends any ? (k: U) => void : never) extends ((k: infer I) => void) ? I : never;
type CtorOf<T> = (arg: UnionToIntersection<T>) => T;

interface Big {
"0": { common?: string; "0"?: number, ref?: Obj<Big["0"]> | Func<Big["0"]>; }
"1": { common?: string; "1"?: number, ref?: Obj<Big["1"]> | Func<Big["1"]>; }
"2": { common?: string; "2"?: number, ref?: Obj<Big["2"]> | Func<Big["2"]>; }
"3": { common?: string; "3"?: number, ref?: Obj<Big["3"]> | Func<Big["3"]>; }
"4": { common?: string; "4"?: number, ref?: Obj<Big["4"]> | Func<Big["4"]>; }
"5": { common?: string; "5"?: number, ref?: Obj<Big["5"]> | Func<Big["5"]>; }
"6": { common?: string; "6"?: number, ref?: Obj<Big["6"]> | Func<Big["6"]>; }
"7": { common?: string; "7"?: number, ref?: Obj<Big["7"]> | Func<Big["7"]>; }
"8": { common?: string; "8"?: number, ref?: Obj<Big["8"]> | Func<Big["8"]>; }
"9": { common?: string; "9"?: number, ref?: Obj<Big["9"]> | Func<Big["9"]>; }
"10": { common?: string; "10"?: number, ref?: Obj<Big["10"]> | Func<Big["10"]>; }
"11": { common?: string; "11"?: number, ref?: Obj<Big["11"]> | Func<Big["11"]>; }
"12": { common?: string; "12"?: number, ref?: Obj<Big["12"]> | Func<Big["12"]>; }
"13": { common?: string; "13"?: number, ref?: Obj<Big["13"]> | Func<Big["13"]>; }
"14": { common?: string; "14"?: number, ref?: Obj<Big["14"]> | Func<Big["14"]>; }
"15": { common?: string; "15"?: number, ref?: Obj<Big["15"]> | Func<Big["15"]>; }
"16": { common?: string; "16"?: number, ref?: Obj<Big["16"]> | Func<Big["16"]>; }
"17": { common?: string; "17"?: number, ref?: Obj<Big["17"]> | Func<Big["17"]>; }
}
declare function getCtor<T extends keyof Big>(comp: T): CtorOf<Big[T]>

declare var all: keyof Big;
const ctor = getCtor(all);
const comp = ctor({ common: "ok", ref: x => console.log(x) });


//// [normalizedIntersectionTooComplex.js]
"use strict";
// Repro from #30050
var ctor = getCtor(all);
var comp = ctor({ common: "ok", ref: function (x) { return console.log(x); } });
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