handle address annotation of slices

dump.go

@@ -79,6 +79,11 @@ func (d *dumpState) indent() {
 func (d *dumpState) unpackValue(v reflect.Value) (val reflect.Value, wasPtr, static bool, addr uintptr) {
 	if v.CanAddr() {
 		addr = v.Addr().Pointer()
+	} else if v.Kind() == reflect.Slice && v.Len() != 0 {
+		elem := v.Index(0)
+		if elem.CanAddr() {
+			addr = elem.Addr().Pointer()
+		}
 	}
 	if v.Kind() == reflect.Interface && !v.IsNil() {
 		return v.Elem(), v.Kind() == reflect.Ptr, false, addr

dump_test.go

@@ -1045,11 +1045,34 @@ var mapElementCycles = []struct {
   },
  },
 }
+`,
+	},
+	// The following test is to confirm that the recursion detection
+	// is not overly zealous by missing identifying the address of slices.
+	// This is https://github.com/kortschak/utter/issues/12.
+	{
+		v: map[interface{}][]interface{}{
+			"outer": []interface{}{
+				map[interface{}]interface{}{
+					"inner": []interface{}{"value"},
+				},
+			},
+		},
+		want: `map[interface{}][]interface{}{
+ string("outer"): []interface{}{
+  map[interface{}]interface{}{
+   string("inner"): []interface{}{
+    string("value"),
+   },
+  },
+ },
+}
 `,
 	},
 }
 
 // https://github.com/kortschak/utter/issues/5
+// https://github.com/kortschak/utter/issues/12
 func TestIssue5Maps(t *testing.T) {
 	for _, test := range mapElementCycles {
 		w := newLimitedWriter(512)

spew_test.go

@@ -193,7 +193,7 @@ func initSpewTests() {
 			" int(1): []interface{}{\n"+
 			"  int( /*%p*/ 5),\n"+
 			"  int( /*%p*/ 5),\n"+
-			"  &int /*%[1]p*/ (5),\n"+
+			"  (*interface{}) /*%[1]p*/ (<already shown>),\n"+
 			"  &int /*%p*/ (5),\n },\n}\n", &c[0], &c[1])},
 		{bs8Default, fCSFdump, []byte{1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3}, "[]uint8{\n" +
 			" 0x01, 0x02, 0x03, 0x04, 0x05, 0x00, 0x01, 0x02, // |........|\n" +