add method Value() Value to InterfaceValue.

use Value() in print to print underlying value
from interface.

before:
	package main
	import "fmt"
	func main() {
		x := []interface{} {1, "hello", 2.5};
		fmt.Println(x[0], x[1], x[2], x);
	}

	1 hello 2.5 [<non-nil interface> <non-nil interface> <non-nil interface>]

after:
	1 hello 2.5 [1 hello 2.5]

R=r
DELTA=44  (22 added, 16 deleted, 6 changed)
OCL=27139
CL=27141

1 files changed, 3 insertions, 4 deletions

diff --git a/src/lib/fmt/print.go b/src/lib/fmt/print.go
index ca5bec934..5fd230f2c 100644
--- a/src/lib/fmt/print.go
+++ b/src/lib/fmt/print.go
@@ -451,12 +451,11 @@ func (p *pp) printField(field reflect.Value) (was_string bool) {
 		}
 		p.add('}');
 	case reflect.InterfaceKind:
-		inter := field.(reflect.InterfaceValue).Get();
-		if inter == nil {
+		value := field.(reflect.InterfaceValue).Value();
+		if value == nil {
 			s = "<nil>"
 		} else {
-			// should never happen since a non-nil interface always has a type
-			s = "<non-nil interface>";
+			return p.printField(value);
 		}
 	default:
 		s = "?" + field.Type().String() + "?";