Go: Fix tensorflow#7175

Change: 149490754

Author: asimshankar

tensorflow/go/genop/internal/genop.go

@@ -162,6 +162,7 @@ func makeOutputList(op *tf.Operation, start int, output string) ([]tf.Output, in
 		"Identifier":  identifier,
 		"IsListArg":   isListArg,
 		"IsListAttr":  isListAttr,
+		"StripLeadingColon": stripLeadingColon,
 	}).Parse(`
 {{if .OptionalAttrs -}}
 {{/* Type for specifying all optional attributes. */ -}}
@@ -174,7 +175,7 @@ type {{.Op.Name}}Attr func(optionalAttr)
 //
 // value: {{MakeComment .Description}}
 {{- end}}
-// If not specified, defaults to {{.DefaultValue}}
+// If not specified, defaults to {{StripLeadingColon .DefaultValue}}
 {{- if .HasMinimum}}
 //
 // {{if IsListAttr .}}REQUIRES: len(value) >= {{.Minimum}}{{else}}REQUIRES: value >= {{.Minimum}}{{end}}
@@ -452,6 +453,23 @@ func isListAttr(attrdef *pb.OpDef_AttrDef) bool {
 	return list
 }
 
+// stripLeadingColon removes the prefix of the string up to the first colon.
+//
+// This is useful when 's' corresponds to a "oneof" protocol buffer message.
+// For example, consider the protocol buffer message:
+//   oneof value { bool b = 1;  int64 i = 2; }
+// String() on a Go corresponding object (using proto.CompactTextString) will
+// print "b:true", or "i:7" etc. This function strips out the leading "b:" or
+// "i:".
+func stripLeadingColon(s fmt.Stringer) string {
+	x := s.String()
+	y := strings.SplitN(x, ":", 2)
+	if len(y) < 2 {
+		return x
+	}
+	return y[1]
+}
+
 func parseTFType(tfType string) (list bool, typ string) {
 	const (
 		listPrefix = "list("

tensorflow/go/genop/internal/genop_test.go

@@ -189,7 +189,7 @@ type DecodeJpegAttr func(optionalAttr)
 // DecodeJpegChannels sets the optional channels attribute to value.
 //
 // value: Number of color channels for the decoded image.
-// If not specified, defaults to i:0
+// If not specified, defaults to 0
 func DecodeJpegChannels(value int64) DecodeJpegAttr {
 	return func(m optionalAttr) {
 		m["channels"] = value
@@ -200,7 +200,7 @@ func DecodeJpegChannels(value int64) DecodeJpegAttr {
 //
 // value: If true use a slower but nicer upscaling of the
 // chroma planes (yuv420/422 only).
-// If not specified, defaults to b:true
+// If not specified, defaults to true
 func DecodeJpegFancyUpscaling(value bool) DecodeJpegAttr {
 	return func(m optionalAttr) {
 		m["fancy_upscaling"] = value
@@ -211,7 +211,7 @@ func DecodeJpegFancyUpscaling(value bool) DecodeJpegAttr {
 //
 // value: The minimum required fraction of lines before a truncated
 // input is accepted.
-// If not specified, defaults to f:1
+// If not specified, defaults to 1
 func DecodeJpegAcceptableFraction(value float32) DecodeJpegAttr {
 	return func(m optionalAttr) {
 		m["acceptable_fraction"] = value
@@ -332,7 +332,7 @@ description: "Some description here."
 type ShapeNAttr func(optionalAttr)
 
 // ShapeNOutType sets the optional out_type attribute to value.
-// If not specified, defaults to type:DT_INT32
+// If not specified, defaults to DT_INT32
 func ShapeNOutType(value tf.DataType) ShapeNAttr {
 	return func(m optionalAttr) {
 		m["out_type"] = value