go/printer: avoid reflect in print

R=gri
CC=golang-dev
https://golang.org/cl/704041

diff --git a/src/pkg/go/printer/printer.go b/src/pkg/go/printer/printer.go
index 4c530d2490a1cf78a602ac08d2da6a31a23e5cb4..17d9100f4bc1647517d8d6dfd68bc6ca8d8431d3 100644 (file)
--- a/src/pkg/go/printer/printer.go
+++ b/src/pkg/go/printer/printer.go
@@ -739,16 +739,13 @@ func (p *printer) writeWhitespace(n int) {
 // space for best comment placement. Then, any leftover whitespace is
 // printed, followed by the actual token.
 //
-func (p *printer) print(args ...) {
-       v := reflect.NewValue(args).(*reflect.StructValue)
-       for i := 0; i < v.NumField(); i++ {
-               f := v.Field(i)
-
+func (p *printer) print(args ...interface{}) {
+       for _, f := range args {
                next := p.pos // estimated position of next item
                var data []byte
                var tag HTMLTag
                isKeyword := false
-               switch x := f.Interface().(type) {
+               switch x := f.(type) {
                case whiteSpace:
                        if x == ignore {
                                // don't add ignore's to the buffer; they
@@ -795,7 +792,8 @@ func (p *printer) print(args ...) {
                                next = x // accurate position of next item
                        }
                default:
-                       panicln("print: unsupported argument type", f.Type().String())
+                       fmt.Fprintf(os.Stderr, "print: unsupported argument type %T\n", f)
+                       panic()
                }
                p.pos = next