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fix: [Symbol.iterator]() lost on union with never (#62661)
1 parent efca03f commit 48244d8

7 files changed

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lines changed

‎src/compiler/checker.ts‎

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@@ -45842,6 +45842,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
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* the `[Symbol.asyncIterator]()` method first, and then the `[Symbol.iterator]()` method.
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*/
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function getIterationTypesOfIterable(type: Type, use: IterationUse, errorNode: Node | undefined) {
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type = getReducedType(type);
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if (type === silentNeverType) {
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return silentNeverIterationTypes;
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}

‎tests/baselines/reference/iterableWithNeverAsUnionMember(target=es5).symbols‎

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//// [tests/cases/compiler/iterableWithNeverAsUnionMember.ts] ////
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=== iterableWithNeverAsUnionMember.ts ===
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declare const o1: { a: "foo" } & { a: "bar" };
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>o1 : Symbol(o1, Decl(iterableWithNeverAsUnionMember.ts, 0, 13))
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>a : Symbol(a, Decl(iterableWithNeverAsUnionMember.ts, 0, 19))
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>a : Symbol(a, Decl(iterableWithNeverAsUnionMember.ts, 0, 34))
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const [el1] = o1; // error
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>el1 : Symbol(el1, Decl(iterableWithNeverAsUnionMember.ts, 1, 7))
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>o1 : Symbol(o1, Decl(iterableWithNeverAsUnionMember.ts, 0, 13))
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// https://github.com/microsoft/TypeScript/issues/62462
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declare var x: number[] | ({ t: "a" } & { t: "b" });
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>x : Symbol(x, Decl(iterableWithNeverAsUnionMember.ts, 4, 11))
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>t : Symbol(t, Decl(iterableWithNeverAsUnionMember.ts, 4, 28))
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>t : Symbol(t, Decl(iterableWithNeverAsUnionMember.ts, 4, 41))
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let [el2] = x; // ok
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>el2 : Symbol(el2, Decl(iterableWithNeverAsUnionMember.ts, 5, 5))
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>x : Symbol(x, Decl(iterableWithNeverAsUnionMember.ts, 4, 11))
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for (const elem of x) { // ok
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>elem : Symbol(elem, Decl(iterableWithNeverAsUnionMember.ts, 7, 10))
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>x : Symbol(x, Decl(iterableWithNeverAsUnionMember.ts, 4, 11))
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elem.toFixed();
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>elem.toFixed : Symbol(Number.toFixed, Decl(lib.es5.d.ts, --, --))
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>elem : Symbol(elem, Decl(iterableWithNeverAsUnionMember.ts, 7, 10))
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>toFixed : Symbol(Number.toFixed, Decl(lib.es5.d.ts, --, --))
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}
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type Shape =
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>Shape : Symbol(Shape, Decl(iterableWithNeverAsUnionMember.ts, 9, 1))
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| { kind: "circle"; radius: number }
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>kind : Symbol(kind, Decl(iterableWithNeverAsUnionMember.ts, 12, 5))
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>radius : Symbol(radius, Decl(iterableWithNeverAsUnionMember.ts, 12, 21))
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| { kind: "rectangle"; width: number; height: number };
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>kind : Symbol(kind, Decl(iterableWithNeverAsUnionMember.ts, 13, 5))
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>width : Symbol(width, Decl(iterableWithNeverAsUnionMember.ts, 13, 24))
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>height : Symbol(height, Decl(iterableWithNeverAsUnionMember.ts, 13, 39))
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type Circle = Shape & { kind: "circle" };
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>Circle : Symbol(Circle, Decl(iterableWithNeverAsUnionMember.ts, 13, 57))
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>Shape : Symbol(Shape, Decl(iterableWithNeverAsUnionMember.ts, 9, 1))
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>kind : Symbol(kind, Decl(iterableWithNeverAsUnionMember.ts, 15, 23))
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function doStuffWithCircle(arg: Circle | [Circle, (newValue: Circle) => void]) {
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>doStuffWithCircle : Symbol(doStuffWithCircle, Decl(iterableWithNeverAsUnionMember.ts, 15, 41))
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>arg : Symbol(arg, Decl(iterableWithNeverAsUnionMember.ts, 17, 27))
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>Circle : Symbol(Circle, Decl(iterableWithNeverAsUnionMember.ts, 13, 57))
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>Circle : Symbol(Circle, Decl(iterableWithNeverAsUnionMember.ts, 13, 57))
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>newValue : Symbol(newValue, Decl(iterableWithNeverAsUnionMember.ts, 17, 51))
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>Circle : Symbol(Circle, Decl(iterableWithNeverAsUnionMember.ts, 13, 57))
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if (Array.isArray(arg)) {
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>Array.isArray : Symbol(ArrayConstructor.isArray, Decl(lib.es5.d.ts, --, --))
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>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
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>isArray : Symbol(ArrayConstructor.isArray, Decl(lib.es5.d.ts, --, --))
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>arg : Symbol(arg, Decl(iterableWithNeverAsUnionMember.ts, 17, 27))
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let [value, setValue] = arg; // ok
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>value : Symbol(value, Decl(iterableWithNeverAsUnionMember.ts, 19, 9))
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>setValue : Symbol(setValue, Decl(iterableWithNeverAsUnionMember.ts, 19, 15))
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>arg : Symbol(arg, Decl(iterableWithNeverAsUnionMember.ts, 17, 27))
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}
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}
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function f1<T extends { a: "foo" } & { a: "bar" }>(x: T) {
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>f1 : Symbol(f1, Decl(iterableWithNeverAsUnionMember.ts, 21, 1))
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>T : Symbol(T, Decl(iterableWithNeverAsUnionMember.ts, 23, 12))
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>a : Symbol(a, Decl(iterableWithNeverAsUnionMember.ts, 23, 23))
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>a : Symbol(a, Decl(iterableWithNeverAsUnionMember.ts, 23, 38))
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>x : Symbol(x, Decl(iterableWithNeverAsUnionMember.ts, 23, 51))
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>T : Symbol(T, Decl(iterableWithNeverAsUnionMember.ts, 23, 12))
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let [y] = x; // error
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>y : Symbol(y, Decl(iterableWithNeverAsUnionMember.ts, 24, 7))
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>x : Symbol(x, Decl(iterableWithNeverAsUnionMember.ts, 23, 51))
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}
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declare const o2: ({ a: "foo" } & { a: "bar" }) | ({ b: "qwe" } & { b: "rty" });
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>o2 : Symbol(o2, Decl(iterableWithNeverAsUnionMember.ts, 27, 13))
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>a : Symbol(a, Decl(iterableWithNeverAsUnionMember.ts, 27, 20))
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>a : Symbol(a, Decl(iterableWithNeverAsUnionMember.ts, 27, 35))
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>b : Symbol(b, Decl(iterableWithNeverAsUnionMember.ts, 27, 52))
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>b : Symbol(b, Decl(iterableWithNeverAsUnionMember.ts, 27, 67))
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const [el3] = o2; // error
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>el3 : Symbol(el3, Decl(iterableWithNeverAsUnionMember.ts, 28, 7))
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>o2 : Symbol(o2, Decl(iterableWithNeverAsUnionMember.ts, 27, 13))
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‎tests/baselines/reference/iterableWithNeverAsUnionMember(target=es5).types‎

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//// [tests/cases/compiler/iterableWithNeverAsUnionMember.ts] ////
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=== iterableWithNeverAsUnionMember.ts ===
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declare const o1: { a: "foo" } & { a: "bar" };
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>o1 : never
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> : ^^^^^
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>a : "foo"
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> : ^^^^^
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>a : "bar"
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> : ^^^^^
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const [el1] = o1; // error
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>el1 : never
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> : ^^^^^
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>o1 : never
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> : ^^^^^
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// https://github.com/microsoft/TypeScript/issues/62462
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declare var x: number[] | ({ t: "a" } & { t: "b" });
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>x : number[]
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> : ^^^^^^^^
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>t : "a"
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> : ^^^
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>t : "b"
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> : ^^^
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let [el2] = x; // ok
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>el2 : number
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> : ^^^^^^
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>x : number[]
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> : ^^^^^^^^
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for (const elem of x) { // ok
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>elem : number
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> : ^^^^^^
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>x : number[]
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> : ^^^^^^^^
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elem.toFixed();
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>elem.toFixed() : string
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> : ^^^^^^
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>elem.toFixed : (fractionDigits?: number) => string
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> : ^ ^^^ ^^^^^
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>elem : number
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> : ^^^^^^
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>toFixed : (fractionDigits?: number) => string
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> : ^ ^^^ ^^^^^
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}
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type Shape =
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>Shape : Shape
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> : ^^^^^
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| { kind: "circle"; radius: number }
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>kind : "circle"
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> : ^^^^^^^^
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>radius : number
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> : ^^^^^^
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| { kind: "rectangle"; width: number; height: number };
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>kind : "rectangle"
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> : ^^^^^^^^^^^
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>width : number
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> : ^^^^^^
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>height : number
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> : ^^^^^^
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type Circle = Shape & { kind: "circle" };
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>Circle : { kind: "circle"; radius: number; } & { kind: "circle"; }
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> : ^^^^^^^^ ^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^
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>kind : "circle"
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> : ^^^^^^^^
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function doStuffWithCircle(arg: Circle | [Circle, (newValue: Circle) => void]) {
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>doStuffWithCircle : (arg: Circle | [Circle, (newValue: Circle) => void]) => void
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> : ^ ^^ ^^^^^^^^^
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>arg : ({ kind: "circle"; radius: number; } & { kind: "circle"; }) | [{ kind: "circle"; radius: number; } & { kind: "circle"; }, (newValue: Circle) => void]
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> : ^^^^^^^^^ ^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^ ^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^ ^^ ^^^^^ ^
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>newValue : { kind: "circle"; radius: number; } & { kind: "circle"; }
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> : ^^^^^^^^ ^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^
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if (Array.isArray(arg)) {
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>Array.isArray(arg) : boolean
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> : ^^^^^^^
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>Array.isArray : (arg: any) => arg is any[]
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> : ^ ^^ ^^^^^
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>Array : ArrayConstructor
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> : ^^^^^^^^^^^^^^^^
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>isArray : (arg: any) => arg is any[]
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> : ^ ^^ ^^^^^
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>arg : ({ kind: "circle"; radius: number; } & { kind: "circle"; }) | [{ kind: "circle"; radius: number; } & { kind: "circle"; }, (newValue: Circle) => void]
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> : ^^^^^^^^^ ^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^ ^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^ ^^ ^^^^^ ^
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let [value, setValue] = arg; // ok
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>value : { kind: "circle"; radius: number; } & { kind: "circle"; }
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> : ^^^^^^^^ ^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^
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>setValue : (newValue: Circle) => void
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> : ^ ^^ ^^^^^
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>arg : [{ kind: "circle"; radius: number; } & { kind: "circle"; }, (newValue: Circle) => void]
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> : ^^^^^^^^^ ^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^ ^^ ^^^^^ ^
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}
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}
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function f1<T extends { a: "foo" } & { a: "bar" }>(x: T) {
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>f1 : <T extends { a: "foo"; } & { a: "bar"; }>(x: T) => void
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> : ^ ^^^^^^^^^ ^^ ^^ ^^^^^^^^^
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>a : "foo"
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> : ^^^^^
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>a : "bar"
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> : ^^^^^
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>x : T
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> : ^
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let [y] = x; // error
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>y : never
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> : ^^^^^
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>x : T
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> : ^
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}
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declare const o2: ({ a: "foo" } & { a: "bar" }) | ({ b: "qwe" } & { b: "rty" });
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>o2 : never
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> : ^^^^^
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>a : "foo"
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> : ^^^^^
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>a : "bar"
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> : ^^^^^
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>b : "qwe"
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> : ^^^^^
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>b : "rty"
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> : ^^^^^
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const [el3] = o2; // error
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>el3 : never
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> : ^^^^^
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>o2 : never
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> : ^^^^^
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‎tests/baselines/reference/iterableWithNeverAsUnionMember(target=esnext).errors.txt‎

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iterableWithNeverAsUnionMember.ts(2,7): error TS2488: Type 'never' must have a '[Symbol.iterator]()' method that returns an iterator.
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iterableWithNeverAsUnionMember.ts(25,7): error TS2488: Type 'T' must have a '[Symbol.iterator]()' method that returns an iterator.
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iterableWithNeverAsUnionMember.ts(29,7): error TS2488: Type 'never' must have a '[Symbol.iterator]()' method that returns an iterator.
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==== iterableWithNeverAsUnionMember.ts (3 errors) ====
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declare const o1: { a: "foo" } & { a: "bar" };
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const [el1] = o1; // error
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~~~~~
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!!! error TS2488: Type 'never' must have a '[Symbol.iterator]()' method that returns an iterator.
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// https://github.com/microsoft/TypeScript/issues/62462
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declare var x: number[] | ({ t: "a" } & { t: "b" });
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let [el2] = x; // ok
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for (const elem of x) { // ok
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elem.toFixed();
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}
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type Shape =
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| { kind: "circle"; radius: number }
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| { kind: "rectangle"; width: number; height: number };
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type Circle = Shape & { kind: "circle" };
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function doStuffWithCircle(arg: Circle | [Circle, (newValue: Circle) => void]) {
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if (Array.isArray(arg)) {
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let [value, setValue] = arg; // ok
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}
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}
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function f1<T extends { a: "foo" } & { a: "bar" }>(x: T) {
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let [y] = x; // error
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~~~
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!!! error TS2488: Type 'T' must have a '[Symbol.iterator]()' method that returns an iterator.
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}
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declare const o2: ({ a: "foo" } & { a: "bar" }) | ({ b: "qwe" } & { b: "rty" });
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const [el3] = o2; // error
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~~~~~
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!!! error TS2488: Type 'never' must have a '[Symbol.iterator]()' method that returns an iterator.

‎tests/baselines/reference/iterableWithNeverAsUnionMember(target=esnext).symbols‎

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//// [tests/cases/compiler/iterableWithNeverAsUnionMember.ts] ////
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=== iterableWithNeverAsUnionMember.ts ===
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declare const o1: { a: "foo" } & { a: "bar" };
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>o1 : Symbol(o1, Decl(iterableWithNeverAsUnionMember.ts, 0, 13))
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>a : Symbol(a, Decl(iterableWithNeverAsUnionMember.ts, 0, 19))
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>a : Symbol(a, Decl(iterableWithNeverAsUnionMember.ts, 0, 34))
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const [el1] = o1; // error
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>el1 : Symbol(el1, Decl(iterableWithNeverAsUnionMember.ts, 1, 7))
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>o1 : Symbol(o1, Decl(iterableWithNeverAsUnionMember.ts, 0, 13))
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// https://github.com/microsoft/TypeScript/issues/62462
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declare var x: number[] | ({ t: "a" } & { t: "b" });
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>x : Symbol(x, Decl(iterableWithNeverAsUnionMember.ts, 4, 11))
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>t : Symbol(t, Decl(iterableWithNeverAsUnionMember.ts, 4, 28))
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>t : Symbol(t, Decl(iterableWithNeverAsUnionMember.ts, 4, 41))
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let [el2] = x; // ok
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>el2 : Symbol(el2, Decl(iterableWithNeverAsUnionMember.ts, 5, 5))
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>x : Symbol(x, Decl(iterableWithNeverAsUnionMember.ts, 4, 11))
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for (const elem of x) { // ok
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>elem : Symbol(elem, Decl(iterableWithNeverAsUnionMember.ts, 7, 10))
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>x : Symbol(x, Decl(iterableWithNeverAsUnionMember.ts, 4, 11))
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elem.toFixed();
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>elem.toFixed : Symbol(Number.toFixed, Decl(lib.es5.d.ts, --, --))
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>elem : Symbol(elem, Decl(iterableWithNeverAsUnionMember.ts, 7, 10))
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>toFixed : Symbol(Number.toFixed, Decl(lib.es5.d.ts, --, --))
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}
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type Shape =
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>Shape : Symbol(Shape, Decl(iterableWithNeverAsUnionMember.ts, 9, 1))
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| { kind: "circle"; radius: number }
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>kind : Symbol(kind, Decl(iterableWithNeverAsUnionMember.ts, 12, 5))
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>radius : Symbol(radius, Decl(iterableWithNeverAsUnionMember.ts, 12, 21))
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| { kind: "rectangle"; width: number; height: number };
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>kind : Symbol(kind, Decl(iterableWithNeverAsUnionMember.ts, 13, 5))
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>width : Symbol(width, Decl(iterableWithNeverAsUnionMember.ts, 13, 24))
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>height : Symbol(height, Decl(iterableWithNeverAsUnionMember.ts, 13, 39))
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type Circle = Shape & { kind: "circle" };
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>Circle : Symbol(Circle, Decl(iterableWithNeverAsUnionMember.ts, 13, 57))
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>Shape : Symbol(Shape, Decl(iterableWithNeverAsUnionMember.ts, 9, 1))
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>kind : Symbol(kind, Decl(iterableWithNeverAsUnionMember.ts, 15, 23))
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function doStuffWithCircle(arg: Circle | [Circle, (newValue: Circle) => void]) {
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>doStuffWithCircle : Symbol(doStuffWithCircle, Decl(iterableWithNeverAsUnionMember.ts, 15, 41))
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>arg : Symbol(arg, Decl(iterableWithNeverAsUnionMember.ts, 17, 27))
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>Circle : Symbol(Circle, Decl(iterableWithNeverAsUnionMember.ts, 13, 57))
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>Circle : Symbol(Circle, Decl(iterableWithNeverAsUnionMember.ts, 13, 57))
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>newValue : Symbol(newValue, Decl(iterableWithNeverAsUnionMember.ts, 17, 51))
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>Circle : Symbol(Circle, Decl(iterableWithNeverAsUnionMember.ts, 13, 57))
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if (Array.isArray(arg)) {
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>Array.isArray : Symbol(ArrayConstructor.isArray, Decl(lib.es5.d.ts, --, --))
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>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --) ... and 4 more)
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>isArray : Symbol(ArrayConstructor.isArray, Decl(lib.es5.d.ts, --, --))
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>arg : Symbol(arg, Decl(iterableWithNeverAsUnionMember.ts, 17, 27))
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let [value, setValue] = arg; // ok
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>value : Symbol(value, Decl(iterableWithNeverAsUnionMember.ts, 19, 9))
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>setValue : Symbol(setValue, Decl(iterableWithNeverAsUnionMember.ts, 19, 15))
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>arg : Symbol(arg, Decl(iterableWithNeverAsUnionMember.ts, 17, 27))
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}
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}
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function f1<T extends { a: "foo" } & { a: "bar" }>(x: T) {
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>f1 : Symbol(f1, Decl(iterableWithNeverAsUnionMember.ts, 21, 1))
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>T : Symbol(T, Decl(iterableWithNeverAsUnionMember.ts, 23, 12))
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>a : Symbol(a, Decl(iterableWithNeverAsUnionMember.ts, 23, 23))
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>a : Symbol(a, Decl(iterableWithNeverAsUnionMember.ts, 23, 38))
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>x : Symbol(x, Decl(iterableWithNeverAsUnionMember.ts, 23, 51))
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>T : Symbol(T, Decl(iterableWithNeverAsUnionMember.ts, 23, 12))
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let [y] = x; // error
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>y : Symbol(y, Decl(iterableWithNeverAsUnionMember.ts, 24, 7))
81+
>x : Symbol(x, Decl(iterableWithNeverAsUnionMember.ts, 23, 51))
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}
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84+
declare const o2: ({ a: "foo" } & { a: "bar" }) | ({ b: "qwe" } & { b: "rty" });
85+
>o2 : Symbol(o2, Decl(iterableWithNeverAsUnionMember.ts, 27, 13))
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>a : Symbol(a, Decl(iterableWithNeverAsUnionMember.ts, 27, 20))
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>a : Symbol(a, Decl(iterableWithNeverAsUnionMember.ts, 27, 35))
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>b : Symbol(b, Decl(iterableWithNeverAsUnionMember.ts, 27, 52))
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>b : Symbol(b, Decl(iterableWithNeverAsUnionMember.ts, 27, 67))
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const [el3] = o2; // error
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>el3 : Symbol(el3, Decl(iterableWithNeverAsUnionMember.ts, 28, 7))
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>o2 : Symbol(o2, Decl(iterableWithNeverAsUnionMember.ts, 27, 13))
94+

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