Allow %p on reference types, for debugging.

(Also fix case sensitivity in test for PTR inside fmt_test.go)
Fixes #441.

R=rsc, iant
CC=golang-dev
https://golang.org/cl/180112

src/pkg/fmt/fmt_test.go

@@ -217,6 +217,11 @@ var fmttests = []fmtTest{
 	fmtTest{"%+v", B{1, 2}, `{i:<1> j:2}`},
 	fmtTest{"%+v", C{1, B{2, 3}}, `{i:1 B:{i:<2> j:3}}`},
 
+	// %p on non-pointers
+	fmtTest{"%p", make(chan int), "PTR"},
+	fmtTest{"%p", make(map[int]int), "PTR"},
+	fmtTest{"%p", make([]int, 1), "PTR"},
+
 	// go syntax
 	fmtTest{"%#v", A{1, 2, "a", []int{1, 2}}, `fmt_test.A{i:1, j:0x2, s:"a", x:[]int{1, 2}}`},
 	fmtTest{"%#v", &b, "(*uint8)(PTR)"},
@@ -233,7 +238,7 @@ func TestSprintf(t *testing.T) {
 			j := i + 2
 			for ; j < len(s); j++ {
 				c := s[j]
-				if (c < '0' || c > '9') && (c < 'a' || c > 'f') {
+				if (c < '0' || c > '9') && (c < 'a' || c > 'f') && (c < 'A' || c > 'F') {
 					break
 				}
 			}

src/pkg/fmt/print.go

@@ -380,14 +380,6 @@ func getFloat64(v reflect.Value) (val float64, ok bool) {
 	return
 }
 
-func getPtr(v reflect.Value) (val uintptr, ok bool) {
-	switch v := v.(type) {
-	case *reflect.PtrValue:
-		return uintptr(v.Get()), true
-	}
-	return
-}
-
 // Convert ASCII to integer.  n is 0 (and got is false) if no number present.
 
 func parsenum(s string, start, end int) (n int, got bool, newi int) {
@@ -808,16 +800,16 @@ func (p *pp) doprintf(format string, v *reflect.StructValue) {
 				goto badtype
 			}
 
-		// pointer
+		// pointer, including addresses of reference types.
 		case 'p':
-			if v, ok := getPtr(field); ok {
-				if v == 0 {
-					p.buf.Write(nilAngleBytes)
-				} else {
-					p.fmt.fmt_s("0x")
-					p.fmt.fmt_uX64(uint64(v))
-				}
-			} else {
+			switch v := field.(type) {
+			case *reflect.PtrValue:
+				p.fmt.fmt_s("0x")
+				p.fmt.fmt_uX64(uint64(v.Get()))
+			case *reflect.ChanValue, *reflect.MapValue, *reflect.SliceValue:
+				p.fmt.fmt_s("0x")
+				p.fmt.fmt_uX64(uint64(field.Addr()))
+			default:
 				goto badtype
 			}