Treat byte slices as binary blobs in Any (#339)

Since `byte` and `uint8` are aliases (as are `rune` and `int32`), `Any` can't distinguish them. To match our intuition about what users likely intend, treat single bytes as integers, byte slices as binary blobs, and runes as integers.

field.go

@@ -224,6 +224,10 @@ func Object(key string, val zapcore.ObjectMarshaler) zapcore.Field {
 // Any takes a key and an arbitrary value and chooses the best way to represent
 // them as a field, falling back to a reflection-based approach only if
 // necessary.
+//
+// Since byte/uint8 and rune/int32 are aliases, Any can't differentiate between
+// them. To minimize suprise, []byte values are treated as binary blobs, byte
+// values are treated as uint8, and runes are always treated as integers.
 func Any(key string, value interface{}) zapcore.Field {
 	switch val := value.(type) {
 	case zapcore.ObjectMarshaler:
@@ -292,8 +296,8 @@ func Any(key string, value interface{}) zapcore.Field {
 		return Uint16s(key, val)
 	case uint8:
 		return Uint8(key, val)
-	case []uint8:
-		return Uint8s(key, val)
+	case []byte:
+		return Binary(key, val)
 	case uintptr:
 		return Uintptr(key, val)
 	case []uintptr:

field_test.go

@@ -112,7 +112,7 @@ func TestFieldConstructors(t *testing.T) {
 		{"Any:Bool", Any("k", true), Bool("k", true)},
 		{"Any:Bools", Any("k", []bool{true}), Bools("k", []bool{true})},
 		{"Any:Byte", Any("k", byte(1)), Uint8("k", 1)},
-		{"Any:Bytes", Any("k", []byte{1}), Uint8s("k", []uint8{1})},
+		{"Any:Bytes", Any("k", []byte{1}), Binary("k", []byte{1})},
 		{"Any:Complex128", Any("k", 1+2i), Complex128("k", 1+2i)},
 		{"Any:Complex128s", Any("k", []complex128{1 + 2i}), Complex128s("k", []complex128{1 + 2i})},
 		{"Any:Complex64", Any("k", complex64(1+2i)), Complex64("k", 1+2i)},
@@ -144,7 +144,7 @@ func TestFieldConstructors(t *testing.T) {
 		{"Any:Uint16", Any("k", uint16(1)), Uint16("k", 1)},
 		{"Any:Uint16s", Any("k", []uint16{1}), Uint16s("k", []uint16{1})},
 		{"Any:Uint8", Any("k", uint8(1)), Uint8("k", 1)},
-		{"Any:Uint8s", Any("k", []uint8{1}), Uint8s("k", []uint8{1})},
+		{"Any:Uint8s", Any("k", []uint8{1}), Binary("k", []uint8{1})},
 		{"Any:Uintptr", Any("k", uintptr(1)), Uintptr("k", 1)},
 		{"Any:Uintptrs", Any("k", []uintptr{1}), Uintptrs("k", []uintptr{1})},
 		{"Any:Time", Any("k", time.Unix(0, 0)), Time("k", time.Unix(0, 0))},