Bypassing unexported field protection using interfaces #1402
Description
by ben.leslie:
It is possible to bypass the protection against copying of protected fields in unprotected types. See thread: http://groups.google.com/group/golang-nuts/browse_frm/thread/10f333af7a3299e0 Example code: <<<< ifhack.go package ifhack import "fmt" type Hack struct { private int } func (h Hack) String() string { return fmt.Sprintf("hack:%d", h.private) } <<<< ifhackCaller.go package main import "fmt" import "ifhack" func main() { var hack ifhack.Hack var hackptr *ifhack.Hack var s fmt.Stringer s = &hack hackptr = &hack fmt.Printf("%s\n", hack.String()) // implicit assignment of unexported field 'private' of ifhack.Hack in method receiver fmt.Printf("%s\n", (&hack).String()) // implicit assignment of unexported field 'private' of ifhack.Hack in method receiver fmt.Printf("%s\n", s.String()) fmt.Printf("%s\n", hackptr.String()) // implicit assignment of unexported field 'private' of ifhack.Hack in method receiver fmt.Printf("%s\n", hack) // implicit assignment of unexported field 'private' of ifhack.Hack in function argument fmt.Printf("%s\n", (&hack)) fmt.Printf("%s\n", s) fmt.Printf("%s\n", hackptr) } Expected behaviour is that it should not be possible to call the String() method indirectly via the Stringer interface.