tests/cases/conformance/expressions/commaOperator/commaOperatorOtherInvalidOperation.ts(6,5): error TS2322: Type 'string' is not assignable to type 'number'. tests/cases/conformance/expressions/commaOperator/commaOperatorOtherInvalidOperation.ts(12,9): error TS2322: Type 'T2' is not assignable to type 'T1'. ==== tests/cases/conformance/expressions/commaOperator/commaOperatorOtherInvalidOperation.ts (2 errors) ==== //Expect to have compiler errors //Comma operator in fuction arguments and return function foo(x: number, y: string) { return x, y; } var resultIsString: number = foo(1, "123"); //error here ~~~~~~~~~~~~~~ !!! error TS2322: Type 'string' is not assignable to type 'number'. //TypeParameters function foo1() { var x: T1; var y: T2; var result: T1 = (x, y); //error here ~~~~~~ !!! error TS2322: Type 'T2' is not assignable to type 'T1'. }