tests/cases/conformance/es6/spread/iteratorSpreadInArray6.ts(15,14): error TS2345: Argument of type 'symbol[]' is not assignable to parameter of type 'number | ReadonlyArray<number>'.
  Type 'symbol[]' is not assignable to type 'ReadonlyArray<number>'.
    Types of property 'concat' are incompatible.
      Type '{ (...items: ReadonlyArray<symbol>[]): symbol[]; (...items: (symbol | ReadonlyArray<symbol>)[]): symbol[]; }' is not assignable to type '{ (...items: ReadonlyArray<number>[]): number[]; (...items: (number | ReadonlyArray<number>)[]): number[]; }'.
        Types of parameters 'items' and 'items' are incompatible.
          Type 'ReadonlyArray<number>' is not assignable to type 'ReadonlyArray<symbol>'.
            Type 'number' is not assignable to type 'symbol'.


==== tests/cases/conformance/es6/spread/iteratorSpreadInArray6.ts (1 errors) ====
    class SymbolIterator {
        next() {
            return {
                value: Symbol(),
                done: false
            };
        }
    
        [Symbol.iterator]() {
            return this;
        }
    }
    
    var array: number[] = [0, 1];
    array.concat([...new SymbolIterator]);
                 ~~~~~~~~~~~~~~~~~~~~~~~
!!! error TS2345: Argument of type 'symbol[]' is not assignable to parameter of type 'number | ReadonlyArray<number>'.
!!! error TS2345:   Type 'symbol[]' is not assignable to type 'ReadonlyArray<number>'.
!!! error TS2345:     Types of property 'concat' are incompatible.
!!! error TS2345:       Type '{ (...items: ReadonlyArray<symbol>[]): symbol[]; (...items: (symbol | ReadonlyArray<symbol>)[]): symbol[]; }' is not assignable to type '{ (...items: ReadonlyArray<number>[]): number[]; (...items: (number | ReadonlyArray<number>)[]): number[]; }'.
!!! error TS2345:         Types of parameters 'items' and 'items' are incompatible.
!!! error TS2345:           Type 'ReadonlyArray<number>' is not assignable to type 'ReadonlyArray<symbol>'.
!!! error TS2345:             Type 'number' is not assignable to type 'symbol'.