In this case, there is not any functionality you can't get through other means: You can set GetBody and the content length header manually, which is what you probably wound up doing if I had to guess (been there too, same hat.) I think Go does this mainly to make basic usage more convenient. Unfortunately though, it makes this unnecessarily subtle footgun in return.

Maybe Go 2 will finally do something about this. I would really like some (hopefully efficient) way to make "transparent" wrapper types that can magically forward methods.