fmt: allow %d on []byte

Fixes #1159.

R=rsc, adg
CC=golang-dev
https://golang.org/cl/2305043

src/pkg/fmt/fmt_test.go

@@ -317,6 +317,8 @@ var fmttests = []fmtTest{
 	// slices with other formats
 	fmtTest{"%#x", []int{1, 2, 15}, `[0x1 0x2 0xf]`},
 	fmtTest{"%x", []int{1, 2, 15}, `[1 2 f]`},
+	fmtTest{"%d", []int{1, 2, 15}, `[1 2 15]`},
+	fmtTest{"%d", []byte{1, 2, 15}, `[1 2 15]`},
 	fmtTest{"%q", []string{"a", "b"}, `["a" "b"]`},
 
 	// renamings
@@ -334,6 +336,7 @@ var fmttests = []fmtTest{
 	fmtTest{"%X", renamedUint64(17), "11"},
 	fmtTest{"%o", renamedUintptr(18), "22"},
 	fmtTest{"%x", renamedString("thing"), "7468696e67"},
+	fmtTest{"%d", renamedBytes([]byte{1, 2, 15}), `[1 2 15]`},
 	fmtTest{"%q", renamedBytes([]byte("hello")), `"hello"`},
 	fmtTest{"%v", renamedFloat(11), "11"},
 	fmtTest{"%v", renamedFloat32(22), "22"},

src/pkg/fmt/print.go

@@ -439,7 +439,7 @@ func (p *pp) fmtString(v string, verb int, goSyntax bool, value interface{}) {
 }
 
 func (p *pp) fmtBytes(v []byte, verb int, goSyntax bool, depth int, value interface{}) {
-	if verb == 'v' {
+	if verb == 'v' || verb == 'd' {
 		if goSyntax {
 			p.buf.Write(bytesBytes)
 		} else {