为什么代码产生错误类型'(int, int)'不符合协议'IntegerLiteralConvertible'

With the code below, I get "Type '(int, int)' does not conform to protocol 'IntegerLiteralConvertible' instead of missing argument as one would expect. What's IntegerLiteralConvertible and why do you think the compiler produces this error instead for the code below?With the code below, I get "Type '(int, int)' d