compare plugin. update compare for oneof types to check this and that types and either call Compare if they are the same or return 1/-1. (#600)

Author: jmarais

plugin/compare/compare.go

@@ -425,11 +425,65 @@ func (p *plugin) generateMessage(file *generator.FileDescriptor, message *genera
 			p.In()
 			p.P(`return -1`)
 			p.Out()
-			p.P(`} else if c := this.`, fieldname, `.Compare(that1.`, fieldname, `); c != 0 {`)
+			p.P(`} else {`)
+			p.In()
+
+			// Generate two type switches in order to compare the
+			// types of the oneofs. If they are of the same type
+			// call Compare, otherwise return 1 or -1.
+			p.P(`thisType := -1`)
+			p.P(`switch this.`, fieldname, `.(type) {`)
+			for i, subfield := range message.Field {
+				if *subfield.OneofIndex == *field.OneofIndex {
+					ccTypeName := p.OneOfTypeName(message, subfield)
+					p.P(`case *`, ccTypeName, `:`)
+					p.In()
+					p.P(`thisType = `, i)
+					p.Out()
+				}
+			}
+			p.P(`default:`)
+			p.In()
+			p.P(`panic(fmt.Sprintf("compare: unexpected type %T in oneof", this.`, fieldname, `))`)
+			p.Out()
+			p.P(`}`)
+
+			p.P(`that1Type := -1`)
+			p.P(`switch that1.`, fieldname, `.(type) {`)
+			for i, subfield := range message.Field {
+				if *subfield.OneofIndex == *field.OneofIndex {
+					ccTypeName := p.OneOfTypeName(message, subfield)
+					p.P(`case *`, ccTypeName, `:`)
+					p.In()
+					p.P(`that1Type = `, i)
+					p.Out()
+				}
+			}
+			p.P(`default:`)
+			p.In()
+			p.P(`panic(fmt.Sprintf("compare: unexpected type %T in oneof", that1.`, fieldname, `))`)
+			p.Out()
+			p.P(`}`)
+
+			p.P(`if thisType == that1Type {`)
+			p.In()
+			p.P(`if c := this.`, fieldname, `.Compare(that1.`, fieldname, `); c != 0 {`)
 			p.In()
 			p.P(`return c`)
 			p.Out()
 			p.P(`}`)
+			p.Out()
+			p.P(`} else if thisType < that1Type {`)
+			p.In()
+			p.P(`return -1`)
+			p.Out()
+			p.P(`} else if thisType > that1Type {`)
+			p.In()
+			p.P(`return 1`)
+			p.Out()
+			p.P(`}`)
+			p.Out()
+			p.P(`}`)
 		} else {
 			p.generateField(file, message, field)
 		}

protoc-gen-gogo/generator/generator.go

@@ -3005,6 +3005,9 @@ func (g *Generator) generateOneofDecls(mc *msgCtx, topLevelFields []topLevelFiel
 		if gogoproto.IsProtoSizer(g.file.FileDescriptorProto, mc.message.DescriptorProto) {
 			g.P(`ProtoSize() int`)
 		}
+		if gogoproto.HasCompare(g.file.FileDescriptorProto, mc.message.DescriptorProto) {
+			g.P(`Compare(interface{}) int`)
+		}
 		g.Out()
 		g.P("}")
 	}

protoc-gen-gogotypes/main.go

@@ -57,7 +57,7 @@ func main() {
 		if strings.HasSuffix(file.GetName(), "struct.proto") {
 			// TODO struct can also get a compare method when
 			// https://github.com/gogo/protobuf/issues/221 is fixed
-			continue
+			//continue
 		}
 		vanity.TurnOnCompareAll(file)
 	}

test/issue322/issue322.pb.go

@@ -7,6 +7,7 @@ option (gogoproto.gostring_all) = true;
 option (gogoproto.populate_all) = true;
 option (gogoproto.equal_all) = true;
 option (gogoproto.testgen_all) = true;
+option (gogoproto.compare_all) = true;
 
 message OneofTest {
     oneof union {