// @target: es2015
// type parameter type is not a valid operand of addition operator
enum E { a, b }

function foo<T, U>(t: T, u: U) {
    let a!: any;
    let b!: boolean;
    let c!: number;
    let d!: string;
    let e!: Object;
    let g!: E;
    let f!: void;

    // type parameter as left operand
    var r1: any = t + a; // ok, one operand is any
    var r2 = t + b;
    var r3 = t + c;
    var r4 = t + d; // ok, one operand is string
    var r5 = t + e;
    var r6 = t + g;
    var r7 = t + f;

    // type parameter as right operand
    var r8 = a + t; // ok, one operand is any
    var r9 = b + t;
    var r10 = c + t;
    var r11 = d + t; // ok, one operand is string
    var r12 = e + t;
    var r13 = g + t;
    var r14 = f + t;

    // other cases
    var r15 = t + null;
    var r16 = t + undefined;
    var r17 = t + t;
    var r18 = t + u;
    var r19 = t + (() => { });
    var r20 = t + [];
}