goprotobuf: Add method to extending message to get list of messages extended.

LGTM=gmlewis
R=gmlewis
CC=golang-codereviews
https://codereview.appspot.com/159790043

4 files changed, 170 insertions, 4 deletions

diff --git a/protoc-gen-go/generator/generator.go b/protoc-gen-go/generator/generator.go
index 4f99191..a86a121 100644
--- a/protoc-gen-go/generator/generator.go
+++ b/protoc-gen-go/generator/generator.go
@@ -160,13 +160,12 @@ func (e *EnumDescriptor) TypeName() (s []string) {
 // Everything but the last element of the full type name, CamelCased.
 // The values of type Foo.Bar are call Foo_value1... not Foo_Bar_value1... .
 func (e *EnumDescriptor) prefix() string {
-	typeName := e.TypeName()
-	ccPrefix := CamelCaseSlice(typeName[0:len(typeName)-1]) + "_"
 	if e.parent == nil {
 		// If the enum is not part of a message, the prefix is just the type name.
-		ccPrefix = CamelCase(*e.Name) + "_"
+		return CamelCase(*e.Name) + "_"
 	}
-	return ccPrefix
+	typeName := e.TypeName()
+	return CamelCaseSlice(typeName[0:len(typeName)-1]) + "_"
 }
 
 // The integer value of the named constant in this enumerated type.
diff --git a/protoc-gen-go/testdata/my_test/test.pb.go b/protoc-gen-go/testdata/my_test/test.pb.go
index 548f458..1165dea 100644
--- a/protoc-gen-go/testdata/my_test/test.pb.go
+++ b/protoc-gen-go/testdata/my_test/test.pb.go
@@ -11,7 +11,9 @@ It is generated from these files:
 It has these top-level messages:
 	Request
 	Reply
+	OtherBase
 	ReplyExtensions
+	OtherReplyExtensions
 	OldReply
 */
 package my_test
@@ -317,6 +319,37 @@ func (m *Reply_Entry) GetXMyFieldName_2() int64 {
 	return 0
 }
 
+type OtherBase struct {
+	Name             *string                   `protobuf:"bytes,1,opt,name=name" json:"name,omitempty"`
+	XXX_extensions   map[int32]proto.Extension `json:"-"`
+	XXX_unrecognized []byte                    `json:"-"`
+}
+
+func (m *OtherBase) Reset()         { *m = OtherBase{} }
+func (m *OtherBase) String() string { return proto.CompactTextString(m) }
+func (*OtherBase) ProtoMessage()    {}
+
+var extRange_OtherBase = []proto.ExtensionRange{
+	{100, 536870911},
+}
+
+func (*OtherBase) ExtensionRangeArray() []proto.ExtensionRange {
+	return extRange_OtherBase
+}
+func (m *OtherBase) ExtensionMap() map[int32]proto.Extension {
+	if m.XXX_extensions == nil {
+		m.XXX_extensions = make(map[int32]proto.Extension)
+	}
+	return m.XXX_extensions
+}
+
+func (m *OtherBase) GetName() string {
+	if m != nil && m.Name != nil {
+		return *m.Name
+	}
+	return ""
+}
+
 type ReplyExtensions struct {
 	XXX_unrecognized []byte `json:"-"`
 }
@@ -333,6 +366,38 @@ var E_ReplyExtensions_Time = &proto.ExtensionDesc{
 	Tag:           "fixed64,101,opt,name=time",
 }
 
+var E_ReplyExtensions_Carrot = &proto.ExtensionDesc{
+	ExtendedType:  (*Reply)(nil),
+	ExtensionType: (*ReplyExtensions)(nil),
+	Field:         105,
+	Name:          "my.test.ReplyExtensions.carrot",
+	Tag:           "bytes,105,opt,name=carrot",
+}
+
+var E_ReplyExtensions_Donut = &proto.ExtensionDesc{
+	ExtendedType:  (*OtherBase)(nil),
+	ExtensionType: (*ReplyExtensions)(nil),
+	Field:         101,
+	Name:          "my.test.ReplyExtensions.donut",
+	Tag:           "bytes,101,opt,name=donut",
+}
+
+type OtherReplyExtensions struct {
+	Key              *int32 `protobuf:"varint,1,opt,name=key" json:"key,omitempty"`
+	XXX_unrecognized []byte `json:"-"`
+}
+
+func (m *OtherReplyExtensions) Reset()         { *m = OtherReplyExtensions{} }
+func (m *OtherReplyExtensions) String() string { return proto.CompactTextString(m) }
+func (*OtherReplyExtensions) ProtoMessage()    {}
+
+func (m *OtherReplyExtensions) GetKey() int32 {
+	if m != nil && m.Key != nil {
+		return *m.Key
+	}
+	return 0
+}
+
 type OldReply struct {
 	XXX_extensions   map[int32]proto.Extension `json:"-"`
 	XXX_unrecognized []byte                    `json:"-"`
@@ -375,11 +440,22 @@ var E_Tag = &proto.ExtensionDesc{
 	Tag:           "bytes,103,opt,name=tag",
 }
 
+var E_Donut = &proto.ExtensionDesc{
+	ExtendedType:  (*Reply)(nil),
+	ExtensionType: (*OtherReplyExtensions)(nil),
+	Field:         106,
+	Name:          "my.test.donut",
+	Tag:           "bytes,106,opt,name=donut",
+}
+
 func init() {
 	proto.RegisterEnum("my.test.HatType", HatType_name, HatType_value)
 	proto.RegisterEnum("my.test.Days", Days_name, Days_value)
 	proto.RegisterEnum("my.test.Request_Color", Request_Color_name, Request_Color_value)
 	proto.RegisterEnum("my.test.Reply_Entry_Game", Reply_Entry_Game_name, Reply_Entry_Game_value)
 	proto.RegisterExtension(E_ReplyExtensions_Time)
+	proto.RegisterExtension(E_ReplyExtensions_Carrot)
+	proto.RegisterExtension(E_ReplyExtensions_Donut)
 	proto.RegisterExtension(E_Tag)
+	proto.RegisterExtension(E_Donut)
 }
diff --git a/protoc-gen-go/testdata/my_test/test.pb.go.golden b/protoc-gen-go/testdata/my_test/test.pb.go.golden
index 548f458..1165dea 100644
--- a/protoc-gen-go/testdata/my_test/test.pb.go.golden
+++ b/protoc-gen-go/testdata/my_test/test.pb.go.golden
@@ -11,7 +11,9 @@ It is generated from these files:
 It has these top-level messages:
 	Request
 	Reply
+	OtherBase
 	ReplyExtensions
+	OtherReplyExtensions
 	OldReply
 */
 package my_test
@@ -317,6 +319,37 @@ func (m *Reply_Entry) GetXMyFieldName_2() int64 {
 	return 0
 }
 
+type OtherBase struct {
+	Name             *string                   `protobuf:"bytes,1,opt,name=name" json:"name,omitempty"`
+	XXX_extensions   map[int32]proto.Extension `json:"-"`
+	XXX_unrecognized []byte                    `json:"-"`
+}
+
+func (m *OtherBase) Reset()         { *m = OtherBase{} }
+func (m *OtherBase) String() string { return proto.CompactTextString(m) }
+func (*OtherBase) ProtoMessage()    {}
+
+var extRange_OtherBase = []proto.ExtensionRange{
+	{100, 536870911},
+}
+
+func (*OtherBase) ExtensionRangeArray() []proto.ExtensionRange {
+	return extRange_OtherBase
+}
+func (m *OtherBase) ExtensionMap() map[int32]proto.Extension {
+	if m.XXX_extensions == nil {
+		m.XXX_extensions = make(map[int32]proto.Extension)
+	}
+	return m.XXX_extensions
+}
+
+func (m *OtherBase) GetName() string {
+	if m != nil && m.Name != nil {
+		return *m.Name
+	}
+	return ""
+}
+
 type ReplyExtensions struct {
 	XXX_unrecognized []byte `json:"-"`
 }
@@ -333,6 +366,38 @@ var E_ReplyExtensions_Time = &proto.ExtensionDesc{
 	Tag:           "fixed64,101,opt,name=time",
 }
 
+var E_ReplyExtensions_Carrot = &proto.ExtensionDesc{
+	ExtendedType:  (*Reply)(nil),
+	ExtensionType: (*ReplyExtensions)(nil),
+	Field:         105,
+	Name:          "my.test.ReplyExtensions.carrot",
+	Tag:           "bytes,105,opt,name=carrot",
+}
+
+var E_ReplyExtensions_Donut = &proto.ExtensionDesc{
+	ExtendedType:  (*OtherBase)(nil),
+	ExtensionType: (*ReplyExtensions)(nil),
+	Field:         101,
+	Name:          "my.test.ReplyExtensions.donut",
+	Tag:           "bytes,101,opt,name=donut",
+}
+
+type OtherReplyExtensions struct {
+	Key              *int32 `protobuf:"varint,1,opt,name=key" json:"key,omitempty"`
+	XXX_unrecognized []byte `json:"-"`
+}
+
+func (m *OtherReplyExtensions) Reset()         { *m = OtherReplyExtensions{} }
+func (m *OtherReplyExtensions) String() string { return proto.CompactTextString(m) }
+func (*OtherReplyExtensions) ProtoMessage()    {}
+
+func (m *OtherReplyExtensions) GetKey() int32 {
+	if m != nil && m.Key != nil {
+		return *m.Key
+	}
+	return 0
+}
+
 type OldReply struct {
 	XXX_extensions   map[int32]proto.Extension `json:"-"`
 	XXX_unrecognized []byte                    `json:"-"`
@@ -375,11 +440,22 @@ var E_Tag = &proto.ExtensionDesc{
 	Tag:           "bytes,103,opt,name=tag",
 }
 
+var E_Donut = &proto.ExtensionDesc{
+	ExtendedType:  (*Reply)(nil),
+	ExtensionType: (*OtherReplyExtensions)(nil),
+	Field:         106,
+	Name:          "my.test.donut",
+	Tag:           "bytes,106,opt,name=donut",
+}
+
 func init() {
 	proto.RegisterEnum("my.test.HatType", HatType_name, HatType_value)
 	proto.RegisterEnum("my.test.Days", Days_name, Days_value)
 	proto.RegisterEnum("my.test.Request_Color", Request_Color_name, Request_Color_value)
 	proto.RegisterEnum("my.test.Reply_Entry_Game", Reply_Entry_Game_name, Reply_Entry_Game_value)
 	proto.RegisterExtension(E_ReplyExtensions_Time)
+	proto.RegisterExtension(E_ReplyExtensions_Carrot)
+	proto.RegisterExtension(E_ReplyExtensions_Donut)
 	proto.RegisterExtension(E_Tag)
+	proto.RegisterExtension(E_Donut)
 }
diff --git a/protoc-gen-go/testdata/my_test/test.proto b/protoc-gen-go/testdata/my_test/test.proto
index 551585d..c957326 100644
--- a/protoc-gen-go/testdata/my_test/test.proto
+++ b/protoc-gen-go/testdata/my_test/test.proto
@@ -90,15 +90,30 @@ message Reply {
   extensions 100 to max;
 }
 
+message OtherBase {
+  optional string name = 1;
+  extensions 100 to max;
+}
+
 message ReplyExtensions {
   extend Reply {
     optional double time = 101;
+    optional ReplyExtensions carrot = 105;
   }
+  extend OtherBase {
+    optional ReplyExtensions donut = 101;
+  }
+}
+
+message OtherReplyExtensions {
+  optional int32 key = 1;
 }
 
 // top-level extension
 extend Reply {
   optional string tag = 103;
+  optional OtherReplyExtensions donut = 106;
+//  optional imp.ImportedMessage elephant = 107;  // extend with message from another file.
 }
 
 message OldReply {