internal/filedesc, internal/filetype: initial commit

The internal/fileinit package is split apart into two packages:
* internal/filedesc constructs descriptors from the raw proto.
It is very similar to the previous internal/fileinit package.
* internal/filetype wraps descriptors with Go type information

Overview:
* The internal/fileinit package will be deleted in a future CL.
It is kept around since the v1 repo currently depends on it.
* The internal/prototype package is deleted. All former usages of it
are now using internal/filedesc instead. Most significantly,
the reflect/protodesc package was almost entirely re-written.
* The internal/impl package drops support for messages that do not
have a Descriptor method (pre-2016). This removes a significant amount
of technical debt.
filedesc.Builder to parse raw descriptors.
* The internal/encoding/defval package now handles enum values by name.

Change-Id: I3957bcc8588a70470fd6c7de1122216b80615ab7
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/182360
Reviewed-by: Damien Neil <dneil@google.com>
diff --git a/reflect/protoregistry/registry_test.go b/reflect/protoregistry/registry_test.go
index de0c4a6..29c87e7 100644
--- a/reflect/protoregistry/registry_test.go
+++ b/reflect/protoregistry/registry_test.go
@@ -12,15 +12,29 @@
 	"github.com/google/go-cmp/cmp"
 	"github.com/google/go-cmp/cmp/cmpopts"
 
+	"google.golang.org/protobuf/encoding/prototext"
 	pimpl "google.golang.org/protobuf/internal/impl"
-	ptype "google.golang.org/protobuf/internal/prototype"
+	pdesc "google.golang.org/protobuf/reflect/protodesc"
 	pref "google.golang.org/protobuf/reflect/protoreflect"
 	preg "google.golang.org/protobuf/reflect/protoregistry"
 
 	test2pb "google.golang.org/protobuf/internal/testprotos/test"
 	testpb "google.golang.org/protobuf/reflect/protoregistry/testprotos"
+	"google.golang.org/protobuf/types/descriptorpb"
 )
 
+func mustMakeFile(s string) pref.FileDescriptor {
+	pb := new(descriptorpb.FileDescriptorProto)
+	if err := prototext.Unmarshal([]byte(s), pb); err != nil {
+		panic(err)
+	}
+	fd, err := pdesc.NewFile(pb, nil)
+	if err != nil {
+		panic(err)
+	}
+	return fd
+}
+
 func TestFiles(t *testing.T) {
 	type (
 		file struct {
@@ -28,7 +42,7 @@
 			Pkg  pref.FullName
 		}
 		testFile struct {
-			inFile  *ptype.File
+			inFile  pref.FileDescriptor
 			wantErr string
 		}
 		testRangePkg struct {
@@ -48,12 +62,12 @@
 	}{{
 		// Test that overlapping packages and files are permitted.
 		files: []testFile{
-			{inFile: &ptype.File{Syntax: pref.Proto2, Path: "test1.proto", Package: "foo.bar"}},
-			{inFile: &ptype.File{Syntax: pref.Proto2, Path: "foo/bar/test.proto", Package: "my.test"}},
-			{inFile: &ptype.File{Syntax: pref.Proto2, Path: "foo/bar/test.proto", Package: "foo.bar.baz"}, wantErr: "already registered"},
-			{inFile: &ptype.File{Syntax: pref.Proto2, Path: "test2.proto", Package: "my.test.package"}},
-			{inFile: &ptype.File{Syntax: pref.Proto2, Package: "foo.bar"}},
-			{inFile: &ptype.File{Syntax: pref.Proto2, Path: "foo/bar/baz/../test.proto", Package: "my.test"}},
+			{inFile: mustMakeFile(`syntax:"proto2" name:"test1.proto" package:"foo.bar"`)},
+			{inFile: mustMakeFile(`syntax:"proto2" name:"foo/bar/test.proto" package:"my.test"`)},
+			{inFile: mustMakeFile(`syntax:"proto2" name:"foo/bar/test.proto" package:"foo.bar.baz"`), wantErr: "already registered"},
+			{inFile: mustMakeFile(`syntax:"proto2" name:"test2.proto" package:"my.test.package"`)},
+			{inFile: mustMakeFile(`syntax:"proto2" name:"" package:"foo.bar"`)},
+			{inFile: mustMakeFile(`syntax:"proto2" name:"foo/bar/baz/../test.proto" package:"my.test"`)},
 		},
 
 		rangePkgs: []testRangePkg{{
@@ -100,104 +114,96 @@
 	}, {
 		// Test when new enum conflicts with existing package.
 		files: []testFile{{
-			inFile: &ptype.File{Syntax: pref.Proto2, Path: "test1a.proto", Package: "foo.bar.baz"},
+			inFile: mustMakeFile(`syntax:"proto2" name:"test1a.proto" package:"foo.bar.baz"`),
 		}, {
-			inFile:  &ptype.File{Syntax: pref.Proto2, Path: "test1b.proto", Enums: []ptype.Enum{{Name: "foo"}}},
+			inFile:  mustMakeFile(`syntax:"proto2" name:"test1b.proto" enum_type:[{name:"foo"}]`),
 			wantErr: `file "test1b.proto" has a name conflict over foo`,
 		}},
 	}, {
 		// Test when new package conflicts with existing enum.
 		files: []testFile{{
-			inFile: &ptype.File{Syntax: pref.Proto2, Path: "test2a.proto", Enums: []ptype.Enum{{Name: "foo"}}},
+			inFile: mustMakeFile(`syntax:"proto2" name:"test2a.proto" enum_type:[{name:"foo"}]`),
 		}, {
-			inFile:  &ptype.File{Syntax: pref.Proto2, Path: "test2b.proto", Package: "foo.bar.baz"},
+			inFile:  mustMakeFile(`syntax:"proto2" name:"test2b.proto" package:"foo.bar.baz"`),
 			wantErr: `file "test2b.proto" has a name conflict over foo`,
 		}},
 	}, {
 		// Test when new enum conflicts with existing enum in same package.
 		files: []testFile{{
-			inFile: &ptype.File{Syntax: pref.Proto2, Path: "test3a.proto", Package: "foo", Enums: []ptype.Enum{{Name: "BAR"}}},
+			inFile: mustMakeFile(`syntax:"proto2" name:"test3a.proto" package:"foo" enum_type:[{name:"BAR"}]`),
 		}, {
-			inFile:  &ptype.File{Syntax: pref.Proto2, Path: "test3b.proto", Package: "foo", Enums: []ptype.Enum{{Name: "BAR"}}},
+			inFile:  mustMakeFile(`syntax:"proto2" name:"test3b.proto" package:"foo" enum_type:[{name:"BAR"}]`),
 			wantErr: `file "test3b.proto" has a name conflict over foo.BAR`,
 		}},
 	}, {
 		files: []testFile{{
-			inFile: &ptype.File{
-				Syntax:  pref.Proto2,
-				Path:    "test1.proto",
-				Package: "fizz.buzz",
-				Messages: []ptype.Message{{
-					Name: "Message",
-					Fields: []ptype.Field{{
-						Name:        "Field",
-						Number:      1,
-						Cardinality: pref.Optional,
-						Kind:        pref.StringKind,
-						OneofName:   "Oneof",
-					}},
-					Oneofs:          []ptype.Oneof{{Name: "Oneof"}},
-					ExtensionRanges: [][2]pref.FieldNumber{{1000, 2000}},
-				}},
-				Enums: []ptype.Enum{{
-					Name:   "Enum",
-					Values: []ptype.EnumValue{{Name: "EnumValue", Number: 0}},
-				}},
-				Extensions: []ptype.Extension{{
-					Name:         "Extension",
-					Number:       1000,
-					Cardinality:  pref.Optional,
-					Kind:         pref.StringKind,
-					ExtendedType: ptype.PlaceholderMessage("fizz.buzz.Message"),
-				}},
-				Services: []ptype.Service{{
-					Name: "Service",
-					Methods: []ptype.Method{{
-						Name:              "Method",
-						InputType:         ptype.PlaceholderMessage("fizz.buzz.Message"),
-						OutputType:        ptype.PlaceholderMessage("fizz.buzz.Message"),
-						IsStreamingClient: true,
-						IsStreamingServer: true,
-					}},
-				}},
-			},
+			inFile: mustMakeFile(`
+				syntax:  "proto2"
+				name:    "test1.proto"
+				package: "fizz.buzz"
+				message_type: [{
+					name: "Message"
+					field: [
+						{name:"Field" number:1 label:LABEL_OPTIONAL type:TYPE_STRING oneof_index:0}
+					]
+					oneof_decl:      [{name:"Oneof"}]
+					extension_range: [{start:1000 end:2000}]
+				}]
+				enum_type: [{
+					name:  "Enum"
+					Value: [{name:"EnumValue" number:0}]
+				}]
+				extension: [
+					{name:"Extension" number:1000 label:LABEL_OPTIONAL type:TYPE_STRING extendee:".fizz.buzz.Message"}
+				]
+				service: [{
+					name: "Service"
+					method: [{
+						name:             "Method"
+						input_type:       ".fizz.buzz.Message"
+						output_type:      ".fizz.buzz.Message"
+						client_streaming: true
+						server_streaming: true
+					}]
+				}]
+			`),
 		}, {
-			inFile: &ptype.File{
-				Syntax:  pref.Proto2,
-				Path:    "test2.proto",
-				Package: "fizz.buzz.gazz",
-				Enums: []ptype.Enum{{
-					Name:   "Enum",
-					Values: []ptype.EnumValue{{Name: "EnumValue", Number: 0}},
-				}},
-			},
+			inFile: mustMakeFile(`
+				syntax:  "proto2"
+				name:    "test2.proto"
+				package: "fizz.buzz.gazz"
+				enum_type: [{
+					name:  "Enum"
+					value: [{name:"EnumValue" number:0}]
+				}]
+			`),
 		}, {
-			inFile: &ptype.File{
-				Syntax:  pref.Proto2,
-				Path:    "test3.proto",
-				Package: "fizz.buzz",
-				Enums: []ptype.Enum{{
-					Name:   "Enum1",
-					Values: []ptype.EnumValue{{Name: "EnumValue1", Number: 0}},
+			inFile: mustMakeFile(`
+				syntax:  "proto2"
+				name:    "test3.proto"
+				package: "fizz.buzz"
+				enum_type: [{
+					name:  "Enum1"
+					value: [{name:"EnumValue1" number:0}]
 				}, {
-					Name:   "Enum2",
-					Values: []ptype.EnumValue{{Name: "EnumValue2", Number: 0}},
-				}},
-			},
+					name:  "Enum2"
+					value: [{name:"EnumValue2" number:0}]
+				}]
+			`),
 		}, {
 			// Make sure we can register without package name.
-			inFile: &ptype.File{
-				Syntax: pref.Proto2,
-				Messages: []ptype.Message{{
-					Name: "Message",
-					Messages: []ptype.Message{{
-						Name: "Message",
-						Messages: []ptype.Message{{
-							Name: "Message",
-						}},
-					}},
-				}},
-			},
+			inFile: mustMakeFile(`
+				syntax: "proto2"
+				message_type: [{
+					name: "Message"
+					nested_type: [{
+						name: "Message"
+						nested_type: [{
+							name: "Message"
+						}]
+					}]
+				}]
+			`),
 		}},
 	}}
 
@@ -208,11 +214,7 @@
 		t.Run("", func(t *testing.T) {
 			var files preg.Files
 			for i, tc := range tt.files {
-				fd, err := ptype.NewFile(tc.inFile)
-				if err != nil {
-					t.Fatalf("file %d, prototype.NewFile() error: %v", i, err)
-				}
-				gotErr := files.Register(fd)
+				gotErr := files.Register(tc.inFile)
 				if ((gotErr == nil) != (tc.wantErr == "")) || !strings.Contains(fmt.Sprint(gotErr), tc.wantErr) {
 					t.Errorf("file %d, Register() = %v, want %v", i, gotErr, tc.wantErr)
 				}
diff --git a/reflect/protoregistry/testprotos/test.pb.go b/reflect/protoregistry/testprotos/test.pb.go
index b6d70e4..4ed4811 100644
--- a/reflect/protoregistry/testprotos/test.pb.go
+++ b/reflect/protoregistry/testprotos/test.pb.go
@@ -5,7 +5,7 @@
 
 import (
 	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
-	protoregistry "google.golang.org/protobuf/reflect/protoregistry"
+	prototype "google.golang.org/protobuf/reflect/prototype"
 	protoiface "google.golang.org/protobuf/runtime/protoiface"
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	sync "sync"
@@ -45,7 +45,7 @@
 }
 
 func (Enum1) Descriptor() protoreflect.EnumDescriptor {
-	return file_test_proto_enumTypes[0].Descriptor()
+	return file_test_proto_enumTypes[0].EnumDescriptor
 }
 
 func (x Enum1) Number() protoreflect.EnumNumber {
@@ -94,7 +94,7 @@
 }
 
 func (Enum2) Descriptor() protoreflect.EnumDescriptor {
-	return file_test_proto_enumTypes[1].Descriptor()
+	return file_test_proto_enumTypes[1].EnumDescriptor
 }
 
 func (x Enum2) Number() protoreflect.EnumNumber {
@@ -143,7 +143,7 @@
 }
 
 func (Enum3) Descriptor() protoreflect.EnumDescriptor {
-	return file_test_proto_enumTypes[2].Descriptor()
+	return file_test_proto_enumTypes[2].EnumDescriptor
 }
 
 func (x Enum3) Number() protoreflect.EnumNumber {
@@ -426,7 +426,7 @@
 	return file_test_proto_rawDescData
 }
 
-var file_test_proto_enumTypes = make([]protoreflect.EnumType, 3)
+var file_test_proto_enumTypes = make([]prototype.Enum, 3)
 var file_test_proto_msgTypes = make([]protoimpl.MessageInfo, 4)
 var file_test_proto_goTypes = []interface{}{
 	(Enum1)(0),       // 0: testprotos.Enum1
@@ -438,16 +438,21 @@
 	(*Message4)(nil), // 6: testprotos.Message4
 }
 var file_test_proto_depIdxs = []int32{
-	3, // testprotos.string_field:extendee -> testprotos.Message1
-	3, // testprotos.enum_field:extendee -> testprotos.Message1
-	3, // testprotos.message_field:extendee -> testprotos.Message1
-	3, // testprotos.Message4.message_field:extendee -> testprotos.Message1
-	3, // testprotos.Message4.enum_field:extendee -> testprotos.Message1
-	3, // testprotos.Message4.string_field:extendee -> testprotos.Message1
-	0, // testprotos.enum_field:type_name -> testprotos.Enum1
-	4, // testprotos.message_field:type_name -> testprotos.Message2
-	4, // testprotos.Message4.message_field:type_name -> testprotos.Message2
-	0, // testprotos.Message4.enum_field:type_name -> testprotos.Enum1
+	3,  // testprotos.string_field:extendee -> testprotos.Message1
+	3,  // testprotos.enum_field:extendee -> testprotos.Message1
+	3,  // testprotos.message_field:extendee -> testprotos.Message1
+	3,  // testprotos.Message4.message_field:extendee -> testprotos.Message1
+	3,  // testprotos.Message4.enum_field:extendee -> testprotos.Message1
+	3,  // testprotos.Message4.string_field:extendee -> testprotos.Message1
+	0,  // testprotos.enum_field:type_name -> testprotos.Enum1
+	4,  // testprotos.message_field:type_name -> testprotos.Message2
+	4,  // testprotos.Message4.message_field:type_name -> testprotos.Message2
+	0,  // testprotos.Message4.enum_field:type_name -> testprotos.Enum1
+	10, // starting offset of method output_type sub-list
+	10, // starting offset of method input_type sub-list
+	6,  // starting offset of extension type_name sub-list
+	0,  // starting offset of extension extendee sub-list
+	0,  // starting offset of field type_name sub-list
 }
 
 func init() { file_test_proto_init() }
@@ -455,18 +460,21 @@
 	if File_test_proto != nil {
 		return
 	}
-	extensionTypes := make([]protoreflect.ExtensionType, 6)
-	File_test_proto = protoimpl.FileBuilder{
-		RawDescriptor:        file_test_proto_rawDesc,
-		GoTypes:              file_test_proto_goTypes,
-		DependencyIndexes:    file_test_proto_depIdxs,
-		LegacyExtensions:     file_test_proto_extDescs,
-		EnumOutputTypes:      file_test_proto_enumTypes,
-		MessageOutputTypes:   file_test_proto_msgTypes,
-		ExtensionOutputTypes: extensionTypes,
-		FilesRegistry:        protoregistry.GlobalFiles,
-		TypesRegistry:        protoregistry.GlobalTypes,
-	}.Init()
+	out := protoimpl.TypeBuilder{
+		File: protoimpl.DescBuilder{
+			RawDescriptor: file_test_proto_rawDesc,
+			NumEnums:      3,
+			NumMessages:   4,
+			NumExtensions: 6,
+			NumServices:   0,
+		},
+		GoTypes:           file_test_proto_goTypes,
+		DependencyIndexes: file_test_proto_depIdxs,
+		MessageInfos:      file_test_proto_msgTypes,
+		LegacyExtensions:  file_test_proto_extDescs,
+	}.Build()
+	File_test_proto = out.File
+	file_test_proto_enumTypes = out.Enums
 	file_test_proto_rawDesc = nil
 	file_test_proto_goTypes = nil
 	file_test_proto_depIdxs = nil