Elision: match 1 or more returned types

[blampe]

(Edit: the below is using 10bff91)

This patch

@@
@@
 func f() (...) {
- fmt.Println("")
+ fmt.Println("hello")
  ...
 }

will match against

package foo

func f() (string, error) {
  fmt.Println("")
  return "", nil
}

but not

package foo

func f() string {
  fmt.Println("")
  return ""
}

I thought the parentheses were forcing more than one return type, so I tried patching without them

@@
@@
 func f() ... {
- return ""
+ return "hello"
 }

however this is not a valid patch:

load patch "repro": parse: repro/0.minus:1:11: found unexpected "..." inside *ast.FieldList

This isn't a big deal -- I can repeat the patch for 1 return type and N return types.

Intuitively, I would have thought "(...)" already represents "zero to N" return types, although I could also be totally misunderstanding the syntax!