swc/crates/swc_ecma_parser/tests/tsc/for-inStatementsInvalid.ts

var aNumber: number;
for (aNumber in {}) { }

var aBoolean: boolean;
for (aBoolean in {}) { }

var aRegExp: RegExp;
for (aRegExp in {}) { }

for (var idx : number in {}) { }

function fn(): void { }
for (var x in fn()) { }

var c : string, d:string, e;

for (var x in c || d) { }
for (var x in e ? c : d) { }
for (var x in 42 ? c : d) { }
for (var x in '' ? c : d) { }
for (var x in 42 ? d[x] : c[x]) { }
for (var x in c[23]) { }

for (var x in (<T>(x: T) => x)) { }
for (var x in function (x: string, y: number) { return x + y }) { }

class A {
    biz() : number{
        for (var x in this.biz()) { }
        for (var x in this.biz) { }
        for (var x in this) { }
        return null;
    }

    static baz() : number {
        for (var x in this) { }
        for (var x in this.baz) { }
        for (var x in this.baz()) { }

        return null;
    }
}

class B extends A {
    boz() {
        for (var x in this.biz()) { }
        for (var x in this.biz) { }
        for (var x in this) { }

        for (var x in super.biz) { }
        for (var x in super.biz()) { }
        return null;
    }
}

interface I {
    id: number;
    [idx: number]: number;
}
var i: I;

for (var x in i[42]) { }