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tests/cases/compiler/instanceofWithStructurallyIdenticalTypes.ts(32,18): error TS2339: Property 'item' does not exist on type 'never'.
==== tests/cases/compiler/instanceofWithStructurallyIdenticalTypes.ts (1 errors) ====
// Repro from #7271
class C1 { item: string }
class C2 { item: string[] }
class C3 { item: string }
function foo1(x: C1 | C2 | C3): string {
if (x instanceof C1) {
return x.item;
}
else if (x instanceof C2) {
return x.item[0];
}
else if (x instanceof C3) {
return x.item;
}
return "error";
}
function isC1(c: C1 | C2 | C3): c is C1 { return c instanceof C1 }
function isC2(c: C1 | C2 | C3): c is C2 { return c instanceof C2 }
function isC3(c: C1 | C2 | C3): c is C3 { return c instanceof C3 }
function foo2(x: C1 | C2 | C3): string {
if (isC1(x)) {
return x.item;
}
else if (isC2(x)) {
return x.item[0];
}
else if (isC3(x)) {
return x.item;
~~~~
!!! error TS2339: Property 'item' does not exist on type 'never'.
}
return "error";
}
// More tests
class A { a: string }
class A1 extends A { }
class A2 { a: string }
class B extends A { b: string }
function goo(x: A) {
if (x instanceof A) {
x; // A
}
else {
x; // never
}
if (x instanceof A1) {
x; // A1
}
else {
x; // A
}
if (x instanceof A2) {
x; // A2
}
else {
x; // A
}
if (x instanceof B) {
x; // B
}
else {
x; // A
}
}
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