将字符串作为参数提供给％09d时，带有sprintf的golang错误

Question

Why doesnt this give a compile error, is it a bug in golang or do I miss something?

intPadded := fmt.Sprintf("%09d", "i am a string" )
fmt.Println("bah" + intPadded)

when executed it gives

bah%!d(string=i am a string)

Answer 1

"If an invalid argument is given for a verb, such as providing a string to %d, the generated string will contain a description of the problem" per http://golang.org/pkg/fmt/

It doesn't give a compile-time error because there is no compile-time error. fmt.Sprintf() is defined as taking ...interface{} for its last argument, which is valid for any sequence of types. The checking is done only at runtime.