The spec currently contains this example:

func f(n int) (res int, err error) {
	if _, err := f(n-1); err != nil {
		return  // invalid return statement: err is shadowed
	}
	return
}

However, nowhere else in the entire document does the string "shadow" appear. I know what shadowing means in the context of Go scopes, but the term is not defined in the spec.

The spec does contain this paragraph:

An identifier declared in a block may be redeclared in an inner block. While the identifier of the inner declaration is in scope, it denotes the entity declared by the inner declaration.

I think we should amend it to also define "shadowing". It is already Go terminology, so I think it would be best to canonically define it. If you google "Go shadowing", you get a lot of third-party definitions, almost none of which point to the spec.

cc @griesemer