Prevent Printf crashing when giving an extra nil argument.

R=rsc, r
CC=golang-dev
https://golang.org/cl/1195041

diff --git a/src/pkg/fmt/print.go b/src/pkg/fmt/print.go
index fb1c3f707db823bfb0b7c899ca5837016870183e..15b7c514529bf626a7e41850665f5de7571ff1b1 100644 (file)
--- a/src/pkg/fmt/print.go
+++ b/src/pkg/fmt/print.go
@@ -1053,8 +1053,10 @@ func (p *pp) doprintf(format string, a []interface{}) {
                p.buf.Write(extraBytes)
                for ; fieldnum < len(a); fieldnum++ {
                        field := a[fieldnum]
-                       p.buf.WriteString(reflect.Typeof(field).String())
-                       p.buf.WriteByte('=')
+                       if field != nil {
+                               p.buf.WriteString(reflect.Typeof(field).String())
+                               p.buf.WriteByte('=')
+                       }
                        p.printField(field, false, false, 0)
                        if fieldnum+1 < len(a) {
                                p.buf.Write(commaSpaceBytes)