fmt: distinguish empty vs nil slice/map in %#v

Also update Scanf tests to cope with DeepEqual
distinguishing empty vs nil slice.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5375091

diff --git a/src/pkg/fmt/fmt_test.go b/src/pkg/fmt/fmt_test.go
index db83f85f9570c55ee269003b437306647c643336..6370560d0bfa65acfa1b71bc21febb7fecc1494e 100644 (file)
--- a/src/pkg/fmt/fmt_test.go
+++ b/src/pkg/fmt/fmt_test.go
@@ -357,6 +357,10 @@ var fmttests = []struct {
        {"%#v", map[string]B{"a": {1, 2}}, `map[string] fmt_test.B{"a":fmt_test.B{I:1, j:2}}`},
        {"%#v", []string{"a", "b"}, `[]string{"a", "b"}`},
        {"%#v", SI{}, `fmt_test.SI{I:interface {}(nil)}`},
+       {"%#v", []int(nil), `[]int(nil)`},
+       {"%#v", []int{}, `[]int{}`},
+       {"%#v", map[int]byte(nil), `map[int] uint8(nil)`},
+       {"%#v", map[int]byte{}, `map[int] uint8{}`},
 
        // slices with other formats
        {"%#x", []int{1, 2, 15}, `[0x1 0x2 0xf]`},

diff --git a/src/pkg/fmt/print.go b/src/pkg/fmt/print.go
index bfa88d187049ab9d6a88030fe60830f2c6cbdd94..7143e07a36e96f6f21b6a041a377535f5c62f46c 100644 (file)
--- a/src/pkg/fmt/print.go
+++ b/src/pkg/fmt/print.go
@@ -795,6 +795,10 @@ BigSwitch:
        case reflect.Map:
                if goSyntax {
                        p.buf.WriteString(f.Type().String())
+                       if f.IsNil() {
+                               p.buf.WriteString("(nil)")
+                               break
+                       }
                        p.buf.WriteByte('{')
                } else {
                        p.buf.Write(mapBytes)
@@ -873,6 +877,10 @@ BigSwitch:
                }
                if goSyntax {
                        p.buf.WriteString(value.Type().String())
+                       if f.IsNil() {
+                               p.buf.WriteString("(nil)")
+                               break
+                       }
                        p.buf.WriteByte('{')
                } else {
                        p.buf.WriteByte('[')

diff --git a/src/pkg/fmt/scan_test.go b/src/pkg/fmt/scan_test.go
index d3c39be60714e5a0ae15760d82b62e0bf15e2144..0689bf3b6e4e35f6508962ec64a0dd0b38ea54df 100644 (file)
--- a/src/pkg/fmt/scan_test.go
+++ b/src/pkg/fmt/scan_test.go
@@ -324,7 +324,7 @@ var x, y Xs
 var z IntString
 
 var multiTests = []ScanfMultiTest{
-       {"", "", nil, nil, ""},
+       {"", "", []interface{}{}, []interface{}{}, ""},
        {"%d", "23", args(&i), args(23), ""},
        {"%2s%3s", "22333", args(&s, &t), args("22", "333"), ""},
        {"%2d%3d", "44555", args(&i, &j), args(44, 555), ""},
@@ -378,7 +378,7 @@ func testScan(name string, t *testing.T, scan func(r io.Reader, a ...interface{}
                }
                val := v.Interface()
                if !reflect.DeepEqual(val, test.out) {
-                       t.Errorf("%s scanning %q: expected %v got %v, type %T", name, test.text, test.out, val, val)
+                       t.Errorf("%s scanning %q: expected %#v got %#v, type %T", name, test.text, test.out, val, val)
                }
        }
 }
@@ -417,7 +417,7 @@ func TestScanf(t *testing.T) {
                }
                val := v.Interface()
                if !reflect.DeepEqual(val, test.out) {
-                       t.Errorf("scanning (%q, %q): expected %v got %v, type %T", test.format, test.text, test.out, val, val)
+                       t.Errorf("scanning (%q, %q): expected %#v got %#v, type %T", test.format, test.text, test.out, val, val)
                }
        }
 }
@@ -520,7 +520,7 @@ func testScanfMulti(name string, t *testing.T) {
                }
                result := resultVal.Interface()
                if !reflect.DeepEqual(result, test.out) {
-                       t.Errorf("scanning (%q, %q): expected %v got %v", test.format, test.text, test.out, result)
+                       t.Errorf("scanning (%q, %q): expected %#v got %#v", test.format, test.text, test.out, result)
                }
        }
 }