internal/cmd/generate-protos: generate internal descfield package

Generate a list of descriptor fields from the descriptor.proto itself
as an internal package. Use these fields for the internal implementation.

Change-Id: Ib1ab0c5c6deb332ba6c8018ef55136b7e5974944
Reviewed-on: https://go-review.googlesource.com/c/164864
Reviewed-by: Herbie Ong <herbie@google.com>

cmd/protoc-gen-go/annotation_test.go

@@ -10,6 +10,7 @@ import (
 	"testing"
 
 	"github.com/golang/protobuf/proto"
+	"github.com/golang/protobuf/v2/internal/descfield"
 	"github.com/golang/protobuf/v2/internal/scalar"
 
 	descriptorpb "github.com/golang/protobuf/v2/types/descriptor"
@@ -35,19 +36,19 @@ func TestAnnotations(t *testing.T) {
 		path                 []int32
 	}{{
 		"type ", "AnnotationsTestEnum", " int32",
-		[]int32{5 /* enum_type */, 0},
+		[]int32{descfield.FileDescriptorProto_EnumType, 0},
 	}, {
 		"\t", "AnnotationsTestEnum_ANNOTATIONS_TEST_ENUM_VALUE", " AnnotationsTestEnum = 0",
-		[]int32{5 /* enum_type */, 0, 2 /* value */, 0},
+		[]int32{descfield.FileDescriptorProto_EnumType, 0, descfield.EnumDescriptorProto_Value, 0},
 	}, {
 		"type ", "AnnotationsTestMessage", " struct {",
-		[]int32{4 /* message_type */, 0},
+		[]int32{descfield.FileDescriptorProto_MessageType, 0},
 	}, {
 		"\t", "AnnotationsTestField", " ",
-		[]int32{4 /* message_type */, 0, 2 /* field */, 0},
+		[]int32{descfield.FileDescriptorProto_MessageType, 0, descfield.DescriptorProto_Field, 0},
 	}, {
 		"func (m *AnnotationsTestMessage) ", "GetAnnotationsTestField", "() string {",
-		[]int32{4 /* message_type */, 0, 2 /* field */, 0},
+		[]int32{descfield.FileDescriptorProto_MessageType, 0, descfield.DescriptorProto_Field, 0},
 	}} {
 		s := want.prefix + want.text + want.suffix
 		pos := bytes.Index(sourceFile, []byte(s))

cmd/protoc-gen-go/internal_gengo/main.go

@@ -18,6 +18,7 @@ import (
 	"unicode/utf8"
 
 	"github.com/golang/protobuf/proto"
+	"github.com/golang/protobuf/v2/internal/descfield"
 	"github.com/golang/protobuf/v2/internal/encoding/tag"
 	"github.com/golang/protobuf/v2/protogen"
 	"github.com/golang/protobuf/v2/reflect/protoreflect"
@@ -118,10 +119,9 @@ func GenerateFile(gen *protogen.Plugin, file *protogen.File) *protogen.Generated
 		g.P("// source: ", f.Desc.Path())
 	}
 	g.P()
-	const filePackageField = 2 // FileDescriptorProto.package
 	g.PrintLeadingComments(protogen.Location{
 		SourceFile: f.Proto.GetName(),
-		Path:       []int32{filePackageField},
+		Path:       []int32{descfield.FileDescriptorProto_Package},
 	})
 	g.P()
 	g.P("package ", f.GoPackageName)

internal/cmd/generate-protos/main.go

@@ -12,6 +12,7 @@ import (
 	"io/ioutil"
 	"os"
 	"os/exec"
+	"path"
 	"path/filepath"
 	"regexp"
 	"strings"
@@ -19,6 +20,7 @@ import (
 	gengogrpc "github.com/golang/protobuf/v2/cmd/protoc-gen-go-grpc/internal_gengogrpc"
 	gengo "github.com/golang/protobuf/v2/cmd/protoc-gen-go/internal_gengo"
 	"github.com/golang/protobuf/v2/protogen"
+	"github.com/golang/protobuf/v2/reflect/protoreflect"
 )
 
 func init() {
@@ -31,6 +33,7 @@ func init() {
 				if file.Generate {
 					gengo.GenerateFile(gen, file)
 					gengogrpc.GenerateFile(gen, file)
+					generateDescriptorFields(gen, file)
 				}
 			}
 			return nil
@@ -43,6 +46,15 @@ var (
 	run       bool
 	protoRoot string
 	repoRoot  string
+
+	generatedPreamble = []string{
+		"// Copyright 2019 The Go Authors. All rights reserved.",
+		"// Use of this source code is governed by a BSD-style.",
+		"// license that can be found in the LICENSE file.",
+		"",
+		"// Code generated by generate-protos. DO NOT EDIT.",
+		"",
+	}
 )
 
 func main() {
@@ -152,6 +164,44 @@ func protoc(args ...string) {
 	check(err)
 }
 
+// generateDescriptorFields generates an internal package for descriptor.proto.
+func generateDescriptorFields(gen *protogen.Plugin, file *protogen.File) {
+	if file.Desc.Path() != "google/protobuf/descriptor.proto" {
+		return
+	}
+
+	const importPath = "github.com/golang/protobuf/v2/internal/descfield"
+	g := gen.NewGeneratedFile(importPath+"/field_gen.go", importPath)
+	for _, s := range generatedPreamble {
+		g.P(s)
+	}
+	g.P("// Package descfield contains constants for field numbers in descriptor.proto.")
+	g.P("package ", path.Base(importPath))
+	g.P("")
+
+	var processMessages func([]*protogen.Message)
+	processMessages = func(messages []*protogen.Message) {
+		for _, message := range messages {
+			g.P("// Field numbers for ", message.Desc.FullName(), ".")
+			g.P("const (")
+			for _, field := range message.Fields {
+				fd := field.Desc
+				typeName := fd.Kind().String()
+				switch fd.Kind() {
+				case protoreflect.EnumKind:
+					typeName = string(fd.EnumType().FullName())
+				case protoreflect.MessageKind, protoreflect.GroupKind:
+					typeName = string(fd.MessageType().FullName())
+				}
+				g.P(message.GoIdent.GoName, "_", field.GoName, "=", fd.Number(), "// ", fd.Cardinality(), " ", typeName)
+			}
+			g.P(")")
+			processMessages(message.Messages)
+		}
+	}
+	processMessages(file.Messages)
+}
+
 func syncOutput(dstDir, srcDir string) {
 	filepath.Walk(srcDir, func(srcPath string, _ os.FileInfo, _ error) error {
 		if !strings.HasSuffix(srcPath, ".go") && !strings.HasSuffix(srcPath, ".meta") {

internal/descfield/field_gen.go

@@ -0,0 +1,240 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style.
+// license that can be found in the LICENSE file.
+
+// Code generated by generate-protos. DO NOT EDIT.
+
+// Package descfield contains constants for field numbers in descriptor.proto.
+package descfield
+
+// Field numbers for google.protobuf.FileDescriptorSet.
+const (
+	FileDescriptorSet_File = 1 // repeated google.protobuf.FileDescriptorProto
+)
+
+// Field numbers for google.protobuf.FileDescriptorProto.
+const (
+	FileDescriptorProto_Name             = 1  // optional string
+	FileDescriptorProto_Package          = 2  // optional string
+	FileDescriptorProto_Dependency       = 3  // repeated string
+	FileDescriptorProto_PublicDependency = 10 // repeated int32
+	FileDescriptorProto_WeakDependency   = 11 // repeated int32
+	FileDescriptorProto_MessageType      = 4  // repeated google.protobuf.DescriptorProto
+	FileDescriptorProto_EnumType         = 5  // repeated google.protobuf.EnumDescriptorProto
+	FileDescriptorProto_Service          = 6  // repeated google.protobuf.ServiceDescriptorProto
+	FileDescriptorProto_Extension        = 7  // repeated google.protobuf.FieldDescriptorProto
+	FileDescriptorProto_Options          = 8  // optional google.protobuf.FileOptions
+	FileDescriptorProto_SourceCodeInfo   = 9  // optional google.protobuf.SourceCodeInfo
+	FileDescriptorProto_Syntax           = 12 // optional string
+)
+
+// Field numbers for google.protobuf.DescriptorProto.
+const (
+	DescriptorProto_Name           = 1  // optional string
+	DescriptorProto_Field          = 2  // repeated google.protobuf.FieldDescriptorProto
+	DescriptorProto_Extension      = 6  // repeated google.protobuf.FieldDescriptorProto
+	DescriptorProto_NestedType     = 3  // repeated google.protobuf.DescriptorProto
+	DescriptorProto_EnumType       = 4  // repeated google.protobuf.EnumDescriptorProto
+	DescriptorProto_ExtensionRange = 5  // repeated google.protobuf.DescriptorProto.ExtensionRange
+	DescriptorProto_OneofDecl      = 8  // repeated google.protobuf.OneofDescriptorProto
+	DescriptorProto_Options        = 7  // optional google.protobuf.MessageOptions
+	DescriptorProto_ReservedRange  = 9  // repeated google.protobuf.DescriptorProto.ReservedRange
+	DescriptorProto_ReservedName   = 10 // repeated string
+)
+
+// Field numbers for google.protobuf.DescriptorProto.ExtensionRange.
+const (
+	DescriptorProto_ExtensionRange_Start   = 1 // optional int32
+	DescriptorProto_ExtensionRange_End     = 2 // optional int32
+	DescriptorProto_ExtensionRange_Options = 3 // optional google.protobuf.ExtensionRangeOptions
+)
+
+// Field numbers for google.protobuf.DescriptorProto.ReservedRange.
+const (
+	DescriptorProto_ReservedRange_Start = 1 // optional int32
+	DescriptorProto_ReservedRange_End   = 2 // optional int32
+)
+
+// Field numbers for google.protobuf.ExtensionRangeOptions.
+const (
+	ExtensionRangeOptions_UninterpretedOption = 999 // repeated google.protobuf.UninterpretedOption
+)
+
+// Field numbers for google.protobuf.FieldDescriptorProto.
+const (
+	FieldDescriptorProto_Name         = 1  // optional string
+	FieldDescriptorProto_Number       = 3  // optional int32
+	FieldDescriptorProto_Label        = 4  // optional google.protobuf.FieldDescriptorProto.Label
+	FieldDescriptorProto_Type         = 5  // optional google.protobuf.FieldDescriptorProto.Type
+	FieldDescriptorProto_TypeName     = 6  // optional string
+	FieldDescriptorProto_Extendee     = 2  // optional string
+	FieldDescriptorProto_DefaultValue = 7  // optional string
+	FieldDescriptorProto_OneofIndex   = 9  // optional int32
+	FieldDescriptorProto_JsonName     = 10 // optional string
+	FieldDescriptorProto_Options      = 8  // optional google.protobuf.FieldOptions
+)
+
+// Field numbers for google.protobuf.OneofDescriptorProto.
+const (
+	OneofDescriptorProto_Name    = 1 // optional string
+	OneofDescriptorProto_Options = 2 // optional google.protobuf.OneofOptions
+)
+
+// Field numbers for google.protobuf.EnumDescriptorProto.
+const (
+	EnumDescriptorProto_Name          = 1 // optional string
+	EnumDescriptorProto_Value         = 2 // repeated google.protobuf.EnumValueDescriptorProto
+	EnumDescriptorProto_Options       = 3 // optional google.protobuf.EnumOptions
+	EnumDescriptorProto_ReservedRange = 4 // repeated google.protobuf.EnumDescriptorProto.EnumReservedRange
+	EnumDescriptorProto_ReservedName  = 5 // repeated string
+)
+
+// Field numbers for google.protobuf.EnumDescriptorProto.EnumReservedRange.
+const (
+	EnumDescriptorProto_EnumReservedRange_Start = 1 // optional int32
+	EnumDescriptorProto_EnumReservedRange_End   = 2 // optional int32
+)
+
+// Field numbers for google.protobuf.EnumValueDescriptorProto.
+const (
+	EnumValueDescriptorProto_Name    = 1 // optional string
+	EnumValueDescriptorProto_Number  = 2 // optional int32
+	EnumValueDescriptorProto_Options = 3 // optional google.protobuf.EnumValueOptions
+)
+
+// Field numbers for google.protobuf.ServiceDescriptorProto.
+const (
+	ServiceDescriptorProto_Name    = 1 // optional string
+	ServiceDescriptorProto_Method  = 2 // repeated google.protobuf.MethodDescriptorProto
+	ServiceDescriptorProto_Options = 3 // optional google.protobuf.ServiceOptions
+)
+
+// Field numbers for google.protobuf.MethodDescriptorProto.
+const (
+	MethodDescriptorProto_Name            = 1 // optional string
+	MethodDescriptorProto_InputType       = 2 // optional string
+	MethodDescriptorProto_OutputType      = 3 // optional string
+	MethodDescriptorProto_Options         = 4 // optional google.protobuf.MethodOptions
+	MethodDescriptorProto_ClientStreaming = 5 // optional bool
+	MethodDescriptorProto_ServerStreaming = 6 // optional bool
+)
+
+// Field numbers for google.protobuf.FileOptions.
+const (
+	FileOptions_JavaPackage               = 1   // optional string
+	FileOptions_JavaOuterClassname        = 8   // optional string
+	FileOptions_JavaMultipleFiles         = 10  // optional bool
+	FileOptions_JavaGenerateEqualsAndHash = 20  // optional bool
+	FileOptions_JavaStringCheckUtf8       = 27  // optional bool
+	FileOptions_OptimizeFor               = 9   // optional google.protobuf.FileOptions.OptimizeMode
+	FileOptions_GoPackage                 = 11  // optional string
+	FileOptions_CcGenericServices         = 16  // optional bool
+	FileOptions_JavaGenericServices       = 17  // optional bool
+	FileOptions_PyGenericServices         = 18  // optional bool
+	FileOptions_PhpGenericServices        = 42  // optional bool
+	FileOptions_Deprecated                = 23  // optional bool
+	FileOptions_CcEnableArenas            = 31  // optional bool
+	FileOptions_ObjcClassPrefix           = 36  // optional string
+	FileOptions_CsharpNamespace           = 37  // optional string
+	FileOptions_SwiftPrefix               = 39  // optional string
+	FileOptions_PhpClassPrefix            = 40  // optional string
+	FileOptions_PhpNamespace              = 41  // optional string
+	FileOptions_PhpMetadataNamespace      = 44  // optional string
+	FileOptions_RubyPackage               = 45  // optional string
+	FileOptions_UninterpretedOption       = 999 // repeated google.protobuf.UninterpretedOption
+)
+
+// Field numbers for google.protobuf.MessageOptions.
+const (
+	MessageOptions_MessageSetWireFormat         = 1   // optional bool
+	MessageOptions_NoStandardDescriptorAccessor = 2   // optional bool
+	MessageOptions_Deprecated                   = 3   // optional bool
+	MessageOptions_MapEntry                     = 7   // optional bool
+	MessageOptions_UninterpretedOption          = 999 // repeated google.protobuf.UninterpretedOption
+)
+
+// Field numbers for google.protobuf.FieldOptions.
+const (
+	FieldOptions_Ctype               = 1   // optional google.protobuf.FieldOptions.CType
+	FieldOptions_Packed              = 2   // optional bool
+	FieldOptions_Jstype              = 6   // optional google.protobuf.FieldOptions.JSType
+	FieldOptions_Lazy                = 5   // optional bool
+	FieldOptions_Deprecated          = 3   // optional bool
+	FieldOptions_Weak                = 10  // optional bool
+	FieldOptions_UninterpretedOption = 999 // repeated google.protobuf.UninterpretedOption
+)
+
+// Field numbers for google.protobuf.OneofOptions.
+const (
+	OneofOptions_UninterpretedOption = 999 // repeated google.protobuf.UninterpretedOption
+)
+
+// Field numbers for google.protobuf.EnumOptions.
+const (
+	EnumOptions_AllowAlias          = 2   // optional bool
+	EnumOptions_Deprecated          = 3   // optional bool
+	EnumOptions_UninterpretedOption = 999 // repeated google.protobuf.UninterpretedOption
+)
+
+// Field numbers for google.protobuf.EnumValueOptions.
+const (
+	EnumValueOptions_Deprecated          = 1   // optional bool
+	EnumValueOptions_UninterpretedOption = 999 // repeated google.protobuf.UninterpretedOption
+)
+
+// Field numbers for google.protobuf.ServiceOptions.
+const (
+	ServiceOptions_Deprecated          = 33  // optional bool
+	ServiceOptions_UninterpretedOption = 999 // repeated google.protobuf.UninterpretedOption
+)
+
+// Field numbers for google.protobuf.MethodOptions.
+const (
+	MethodOptions_Deprecated          = 33  // optional bool
+	MethodOptions_IdempotencyLevel    = 34  // optional google.protobuf.MethodOptions.IdempotencyLevel
+	MethodOptions_UninterpretedOption = 999 // repeated google.protobuf.UninterpretedOption
+)
+
+// Field numbers for google.protobuf.UninterpretedOption.
+const (
+	UninterpretedOption_Name             = 2 // repeated google.protobuf.UninterpretedOption.NamePart
+	UninterpretedOption_IdentifierValue  = 3 // optional string
+	UninterpretedOption_PositiveIntValue = 4 // optional uint64
+	UninterpretedOption_NegativeIntValue = 5 // optional int64
+	UninterpretedOption_DoubleValue      = 6 // optional double
+	UninterpretedOption_StringValue      = 7 // optional bytes
+	UninterpretedOption_AggregateValue   = 8 // optional string
+)
+
+// Field numbers for google.protobuf.UninterpretedOption.NamePart.
+const (
+	UninterpretedOption_NamePart_NamePart    = 1 // required string
+	UninterpretedOption_NamePart_IsExtension = 2 // required bool
+)
+
+// Field numbers for google.protobuf.SourceCodeInfo.
+const (
+	SourceCodeInfo_Location = 1 // repeated google.protobuf.SourceCodeInfo.Location
+)
+
+// Field numbers for google.protobuf.SourceCodeInfo.Location.
+const (
+	SourceCodeInfo_Location_Path                    = 1 // repeated int32
+	SourceCodeInfo_Location_Span                    = 2 // repeated int32
+	SourceCodeInfo_Location_LeadingComments         = 3 // optional string
+	SourceCodeInfo_Location_TrailingComments        = 4 // optional string
+	SourceCodeInfo_Location_LeadingDetachedComments = 6 // repeated string
+)
+
+// Field numbers for google.protobuf.GeneratedCodeInfo.
+const (
+	GeneratedCodeInfo_Annotation = 1 // repeated google.protobuf.GeneratedCodeInfo.Annotation
+)
+
+// Field numbers for google.protobuf.GeneratedCodeInfo.Annotation.
+const (
+	GeneratedCodeInfo_Annotation_Path       = 1 // repeated int32
+	GeneratedCodeInfo_Annotation_SourceFile = 2 // optional string
+	GeneratedCodeInfo_Annotation_Begin      = 3 // optional int32
+	GeneratedCodeInfo_Annotation_End        = 4 // optional int32
+)

internal/fileinit/desc_init.go

@@ -5,6 +5,7 @@
 package fileinit
 
 import (
+	descfield "github.com/golang/protobuf/v2/internal/descfield"
 	wire "github.com/golang/protobuf/v2/internal/encoding/wire"
 	pref "github.com/golang/protobuf/v2/reflect/protoreflect"
 )
@@ -88,36 +89,36 @@ func (fd *fileDesc) unmarshalSeed(b []byte) {
 			v, m := wire.ConsumeBytes(b)
 			b = b[m:]
 			switch num {
-			case fileDesc_Name:
+			case descfield.FileDescriptorProto_Name:
 				fd.path = nb.MakeString(v)
-			case fileDesc_Package:
+			case descfield.FileDescriptorProto_Package:
 				fd.protoPackage = pref.FullName(nb.MakeString(v))
-			case fileDesc_Enums:
+			case descfield.FileDescriptorProto_EnumType:
-				if prevField != fileDesc_Enums {
+				if prevField != descfield.FileDescriptorProto_EnumType {
 					if numEnums > 0 {
 						panic("non-contiguous repeated field")
 					}
 					posEnums = len(b0) - len(b) - n - m
 				}
 				numEnums++
-			case fileDesc_Messages:
+			case descfield.FileDescriptorProto_MessageType:
-				if prevField != fileDesc_Messages {
+				if prevField != descfield.FileDescriptorProto_MessageType {
 					if numMessages > 0 {
 						panic("non-contiguous repeated field")
 					}
 					posMessages = len(b0) - len(b) - n - m
 				}
 				numMessages++
-			case fileDesc_Extensions:
+			case descfield.FileDescriptorProto_Extension:
-				if prevField != fileDesc_Extensions {
+				if prevField != descfield.FileDescriptorProto_Extension {
 					if numExtensions > 0 {
 						panic("non-contiguous repeated field")
 					}
 					posExtensions = len(b0) - len(b) - n - m
 				}
 				numExtensions++
-			case fileDesc_Services:
+			case descfield.FileDescriptorProto_Service:
-				if prevField != fileDesc_Services {
+				if prevField != descfield.FileDescriptorProto_Service {
 					if numServices > 0 {
 						panic("non-contiguous repeated field")
 					}
@@ -199,7 +200,7 @@ func (ed *enumDesc) unmarshalSeed(b []byte, nb *nameBuilder, pf *fileDesc, pd pr
 			v, m := wire.ConsumeBytes(b)
 			b = b[m:]
 			switch num {
-			case enumDesc_Name:
+			case descfield.EnumDescriptorProto_Name:
 				ed.fullName = nb.AppendFullName(pd.FullName(), v)
 			}
 		default:
@@ -226,26 +227,26 @@ func (md *messageDesc) unmarshalSeed(b []byte, nb *nameBuilder, pf *fileDesc, pd
 			v, m := wire.ConsumeBytes(b)
 			b = b[m:]
 			switch num {
-			case messageDesc_Name:
+			case descfield.DescriptorProto_Name:
 				md.fullName = nb.AppendFullName(pd.FullName(), v)
-			case messageDesc_Enums:
+			case descfield.DescriptorProto_EnumType:
-				if prevField != messageDesc_Enums {
+				if prevField != descfield.DescriptorProto_EnumType {
 					if numEnums > 0 {
 						panic("non-contiguous repeated field")
 					}
 					posEnums = len(b0) - len(b) - n - m
 				}
 				numEnums++
-			case messageDesc_Messages:
+			case descfield.DescriptorProto_NestedType:
-				if prevField != messageDesc_Messages {
+				if prevField != descfield.DescriptorProto_NestedType {
 					if numMessages > 0 {
 						panic("non-contiguous repeated field")
 					}
 					posMessages = len(b0) - len(b) - n - m
 				}
 				numMessages++
-			case messageDesc_Extensions:
+			case descfield.DescriptorProto_Extension:
-				if prevField != messageDesc_Extensions {
+				if prevField != descfield.DescriptorProto_Extension {
 					if numExtensions > 0 {
 						panic("non-contiguous repeated field")
 					}
@@ -315,14 +316,14 @@ func (xd *extensionDesc) unmarshalSeed(b []byte, nb *nameBuilder, pf *fileDesc,
 			v, m := wire.ConsumeVarint(b)
 			b = b[m:]
 			switch num {
-			case fieldDesc_Number:
+			case descfield.FieldDescriptorProto_Number:
 				xd.number = pref.FieldNumber(v)
 			}
 		case wire.BytesType:
 			v, m := wire.ConsumeBytes(b)
 			b = b[m:]
 			switch num {
-			case fieldDesc_Name:
+			case descfield.FieldDescriptorProto_Name:
 				xd.fullName = nb.AppendFullName(pd.FullName(), v)
 			}
 		default:
@@ -345,7 +346,7 @@ func (sd *serviceDesc) unmarshalSeed(b []byte, nb *nameBuilder, pf *fileDesc, pd
 			v, m := wire.ConsumeBytes(b)
 			b = b[m:]
 			switch num {
-			case serviceDesc_Name:
+			case descfield.ServiceDescriptorProto_Name:
 				sd.fullName = nb.AppendFullName(pd.FullName(), v)
 			}
 		default:

internal/fileinit/desc_lazy.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"reflect"
 
+	descfield "github.com/golang/protobuf/v2/internal/descfield"
 	defval "github.com/golang/protobuf/v2/internal/encoding/defval"
 	wire "github.com/golang/protobuf/v2/internal/encoding/wire"
 	pimpl "github.com/golang/protobuf/v2/internal/impl"
@@ -344,16 +345,16 @@ func (fd *fileDesc) unmarshalFull(b []byte) {
 			v, m := wire.ConsumeVarint(b)
 			b = b[m:]
 			switch num {
-			case fileDesc_PublicImports:
+			case descfield.FileDescriptorProto_PublicDependency:
 				fd.lazy.imports[v].IsPublic = true
-			case fileDesc_WeakImports:
+			case descfield.FileDescriptorProto_WeakDependency:
 				fd.lazy.imports[v].IsWeak = true
 			}
 		case wire.BytesType:
 			v, m := wire.ConsumeBytes(b)
 			b = b[m:]
 			switch num {
-			case fileDesc_Syntax:
+			case descfield.FileDescriptorProto_Syntax:
 				hasSyntax = true
 				switch string(v) {
 				case "proto2":
@@ -363,23 +364,23 @@ func (fd *fileDesc) unmarshalFull(b []byte) {
 				default:
 					panic("invalid syntax")
 				}
-			case fileDesc_Imports:
+			case descfield.FileDescriptorProto_Dependency:
 				fd.lazy.imports = append(fd.lazy.imports, pref.FileImport{
 					FileDescriptor: ptype.PlaceholderFile(nb.MakeString(v), ""),
 				})
-			case fileDesc_Enums:
+			case descfield.FileDescriptorProto_EnumType:
 				fd.enums.list[enumIdx].unmarshalFull(v, nb)
 				enumIdx++
-			case fileDesc_Messages:
+			case descfield.FileDescriptorProto_MessageType:
 				fd.messages.list[messageIdx].unmarshalFull(v, nb)
 				messageIdx++
-			case fileDesc_Extensions:
+			case descfield.FileDescriptorProto_Extension:
 				fd.extensions.list[extensionIdx].unmarshalFull(v, nb)
 				extensionIdx++
-			case fileDesc_Services:
+			case descfield.FileDescriptorProto_Service:
 				fd.services.list[serviceIdx].unmarshalFull(v, nb)
 				serviceIdx++
-			case fileDesc_Options:
+			case descfield.FileDescriptorProto_Options:
 				fd.lazy.options = append(fd.lazy.options, v...)
 			}
 		default:
@@ -405,13 +406,13 @@ func (ed *enumDesc) unmarshalFull(b []byte, nb *nameBuilder) {
 			v, m := wire.ConsumeBytes(b)
 			b = b[m:]
 			switch num {
-			case enumDesc_Values:
+			case descfield.EnumDescriptorProto_Value:
 				rawValues = append(rawValues, v)
-			case enumDesc_ReservedNames:
+			case descfield.EnumDescriptorProto_ReservedName:
 				ed.lazy.resvNames.list = append(ed.lazy.resvNames.list, pref.Name(nb.MakeString(v)))
-			case enumDesc_ReservedRanges:
+			case descfield.EnumDescriptorProto_ReservedRange:
 				ed.lazy.resvRanges.list = append(ed.lazy.resvRanges.list, unmarshalEnumReservedRange(v))
-			case enumDesc_Options:
+			case descfield.EnumDescriptorProto_Options:
 				ed.lazy.options = append(ed.lazy.options, v...)
 			}
 		default:
@@ -439,9 +440,9 @@ func unmarshalEnumReservedRange(b []byte) (r [2]pref.EnumNumber) {
 			v, m := wire.ConsumeVarint(b)
 			b = b[m:]
 			switch num {
-			case enumReservedRange_Start:
+			case descfield.EnumDescriptorProto_EnumReservedRange_Start:
 				r[0] = pref.EnumNumber(v)
-			case enumReservedRange_End:
+			case descfield.EnumDescriptorProto_EnumReservedRange_End:
 				r[1] = pref.EnumNumber(v)
 			}
 		default:
@@ -465,16 +466,16 @@ func (vd *enumValueDesc) unmarshalFull(b []byte, nb *nameBuilder, pf *fileDesc,
 			v, m := wire.ConsumeVarint(b)
 			b = b[m:]
 			switch num {
-			case enumValueDesc_Number:
+			case descfield.EnumValueDescriptorProto_Number:
 				vd.number = pref.EnumNumber(v)
 			}
 		case wire.BytesType:
 			v, m := wire.ConsumeBytes(b)
 			b = b[m:]
 			switch num {
-			case enumValueDesc_Name:
+			case descfield.EnumValueDescriptorProto_Name:
 				vd.fullName = nb.AppendFullName(pd.FullName(), v)
-			case enumValueDesc_Options:
+			case descfield.EnumValueDescriptorProto_Options:
 				vd.options = append(vd.options, v...)
 			}
 		default:
@@ -498,28 +499,28 @@ func (md *messageDesc) unmarshalFull(b []byte, nb *nameBuilder) {
 			v, m := wire.ConsumeBytes(b)
 			b = b[m:]
 			switch num {
-			case messageDesc_Fields:
+			case descfield.DescriptorProto_Field:
 				rawFields = append(rawFields, v)
-			case messageDesc_Oneofs:
+			case descfield.DescriptorProto_OneofDecl:
 				rawOneofs = append(rawOneofs, v)
-			case messageDesc_ReservedNames:
+			case descfield.DescriptorProto_ReservedName:
 				md.lazy.resvNames.list = append(md.lazy.resvNames.list, pref.Name(nb.MakeString(v)))
-			case messageDesc_ReservedRanges:
+			case descfield.DescriptorProto_ReservedRange:
 				md.lazy.resvRanges.list = append(md.lazy.resvRanges.list, unmarshalMessageReservedRange(v))
-			case messageDesc_ExtensionRanges:
+			case descfield.DescriptorProto_ExtensionRange:
 				r, opts := unmarshalMessageExtensionRange(v)
 				md.lazy.extRanges.list = append(md.lazy.extRanges.list, r)
 				md.lazy.extRangeOptions = append(md.lazy.extRangeOptions, opts)
-			case messageDesc_Enums:
+			case descfield.DescriptorProto_EnumType:
 				md.enums.list[enumIdx].unmarshalFull(v, nb)
 				enumIdx++
-			case messageDesc_Messages:
+			case descfield.DescriptorProto_NestedType:
 				md.messages.list[messageIdx].unmarshalFull(v, nb)
 				messageIdx++
-			case messageDesc_Extensions:
+			case descfield.DescriptorProto_Extension:
 				md.extensions.list[extensionIdx].unmarshalFull(v, nb)
 				extensionIdx++
-			case messageDesc_Options:
+			case descfield.DescriptorProto_Options:
 				md.unmarshalOptions(v)
 			}
 		default:
@@ -557,7 +558,7 @@ func (md *messageDesc) unmarshalOptions(b []byte) {
 			v, m := wire.ConsumeVarint(b)
 			b = b[m:]
 			switch num {
-			case messageOptions_IsMapEntry:
+			case descfield.MessageOptions_MapEntry:
 				md.lazy.isMapEntry = wire.DecodeBool(v)
 			}
 		default:
@@ -576,9 +577,9 @@ func unmarshalMessageReservedRange(b []byte) (r [2]pref.FieldNumber) {
 			v, m := wire.ConsumeVarint(b)
 			b = b[m:]
 			switch num {
-			case messageReservedRange_Start:
+			case descfield.DescriptorProto_ReservedRange_Start:
 				r[0] = pref.FieldNumber(v)
-			case messageReservedRange_End:
+			case descfield.DescriptorProto_ReservedRange_End:
 				r[1] = pref.FieldNumber(v)
 			}
 		default:
@@ -598,16 +599,16 @@ func unmarshalMessageExtensionRange(b []byte) (r [2]pref.FieldNumber, opts []byt
 			v, m := wire.ConsumeVarint(b)
 			b = b[m:]
 			switch num {
-			case messageExtensionRange_Start:
+			case descfield.DescriptorProto_ExtensionRange_Start:
 				r[0] = pref.FieldNumber(v)
-			case messageExtensionRange_End:
+			case descfield.DescriptorProto_ExtensionRange_End:
 				r[1] = pref.FieldNumber(v)
 			}
 		case wire.BytesType:
 			v, m := wire.ConsumeBytes(b)
 			b = b[m:]
 			switch num {
-			case messageExtensionRange_Options:
+			case descfield.DescriptorProto_ExtensionRange_Options:
 				opts = append(opts, v...)
 			}
 		default:
@@ -633,13 +634,13 @@ func (fd *fieldDesc) unmarshalFull(b []byte, nb *nameBuilder, pf *fileDesc, pd p
 			v, m := wire.ConsumeVarint(b)
 			b = b[m:]
 			switch num {
-			case fieldDesc_Number:
+			case descfield.FieldDescriptorProto_Number:
 				fd.number = pref.FieldNumber(v)
-			case fieldDesc_Cardinality:
+			case descfield.FieldDescriptorProto_Label:
 				fd.cardinality = pref.Cardinality(v)
-			case fieldDesc_Kind:
+			case descfield.FieldDescriptorProto_Type:
 				fd.kind = pref.Kind(v)
-			case fieldDesc_OneofIndex:
+			case descfield.FieldDescriptorProto_OneofIndex:
 				// In messageDesc.UnmarshalFull, we allocate slices for both
 				// the field and oneof descriptors before unmarshaling either
 				// of them. This ensures pointers to slice elements are stable.
@@ -654,17 +655,17 @@ func (fd *fieldDesc) unmarshalFull(b []byte, nb *nameBuilder, pf *fileDesc, pd p
 			v, m := wire.ConsumeBytes(b)
 			b = b[m:]
 			switch num {
-			case fieldDesc_Name:
+			case descfield.FieldDescriptorProto_Name:
 				fd.fullName = nb.AppendFullName(pd.FullName(), v)
-			case fieldDesc_JSONName:
+			case descfield.FieldDescriptorProto_JsonName:
 				fd.hasJSONName = true
 				fd.jsonName = nb.MakeString(v)
-			case fieldDesc_Default:
+			case descfield.FieldDescriptorProto_DefaultValue:
 				fd.defVal.has = true
 				rawDefVal = v
-			case fieldDesc_TypeName:
+			case descfield.FieldDescriptorProto_TypeName:
 				rawTypeName = v
-			case fieldDesc_Options:
+			case descfield.FieldDescriptorProto_Options:
 				fd.unmarshalOptions(v)
 			}
 		default:
@@ -703,10 +704,10 @@ func (fd *fieldDesc) unmarshalOptions(b []byte) {
 			v, m := wire.ConsumeVarint(b)
 			b = b[m:]
 			switch num {
-			case fieldOptions_IsPacked:
+			case descfield.FieldOptions_Packed:
 				fd.hasPacked = true
 				fd.isPacked = wire.DecodeBool(v)
-			case fieldOptions_IsWeak:
+			case descfield.FieldOptions_Weak:
 				fd.isWeak = wire.DecodeBool(v)
 			}
 		default:
@@ -729,9 +730,9 @@ func (od *oneofDesc) unmarshalFull(b []byte, nb *nameBuilder, pf *fileDesc, pd p
 			v, m := wire.ConsumeBytes(b)
 			b = b[m:]
 			switch num {
-			case oneofDesc_Name:
+			case descfield.OneofDescriptorProto_Name:
 				od.fullName = nb.AppendFullName(pd.FullName(), v)
-			case oneofDesc_Options:
+			case descfield.OneofDescriptorProto_Options:
 				od.options = append(od.options, v...)
 			}
 		default:
@@ -754,22 +755,22 @@ func (xd *extensionDesc) unmarshalFull(b []byte, nb *nameBuilder) {
 			v, m := wire.ConsumeVarint(b)
 			b = b[m:]
 			switch num {
-			case fieldDesc_Cardinality:
+			case descfield.FieldDescriptorProto_Label:
 				xd.lazy.cardinality = pref.Cardinality(v)
-			case fieldDesc_Kind:
+			case descfield.FieldDescriptorProto_Type:
 				xd.lazy.kind = pref.Kind(v)
 			}
 		case wire.BytesType:
 			v, m := wire.ConsumeBytes(b)
 			b = b[m:]
 			switch num {
-			case fieldDesc_JSONName:
+			case descfield.FieldDescriptorProto_JsonName:
 				xd.lazy.hasJSONName = true
 				xd.lazy.jsonName = nb.MakeString(v)
-			case fieldDesc_Default:
+			case descfield.FieldDescriptorProto_DefaultValue:
 				xd.lazy.defVal.has = true
 				rawDefVal = v
-			case fieldDesc_Options:
+			case descfield.FieldDescriptorProto_Options:
 				xd.unmarshalOptions(v)
 			}
 		default:
@@ -799,7 +800,7 @@ func (xd *extensionDesc) unmarshalOptions(b []byte) {
 			v, m := wire.ConsumeVarint(b)
 			b = b[m:]
 			switch num {
-			case fieldOptions_IsPacked:
+			case descfield.FieldOptions_Packed:
 				xd.lazy.isPacked = wire.DecodeBool(v)
 			}
 		default:
@@ -820,9 +821,9 @@ func (sd *serviceDesc) unmarshalFull(b []byte, nb *nameBuilder) {
 			v, m := wire.ConsumeBytes(b)
 			b = b[m:]
 			switch num {
-			case serviceDesc_Methods:
+			case descfield.ServiceDescriptorProto_Method:
 				rawMethods = append(rawMethods, v)
-			case serviceDesc_Options:
+			case descfield.ServiceDescriptorProto_Options:
 				sd.lazy.options = append(sd.lazy.options, v...)
 			}
 		default:
@@ -854,18 +855,18 @@ func (md *methodDesc) unmarshalFull(b []byte, nb *nameBuilder, pf *fileDesc, pd
 			v, m := wire.ConsumeVarint(b)
 			b = b[m:]
 			switch num {
-			case methodDesc_IsStreamingClient:
+			case descfield.MethodDescriptorProto_ClientStreaming:
 				md.isStreamingClient = wire.DecodeBool(v)
-			case methodDesc_IsStreamingServer:
+			case descfield.MethodDescriptorProto_ServerStreaming:
 				md.isStreamingServer = wire.DecodeBool(v)
 			}
 		case wire.BytesType:
 			v, m := wire.ConsumeBytes(b)
 			b = b[m:]
 			switch num {
-			case methodDesc_Name:
+			case descfield.MethodDescriptorProto_Name:
 				md.fullName = nb.AppendFullName(pd.FullName(), v)
-			case methodDesc_Options:
+			case descfield.MethodDescriptorProto_Options:
 				md.options = append(md.options, v...)
 			}
 		default:

internal/fileinit/desc_wire.go

@@ -1,94 +0,0 @@
-// Copyright 2018 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package fileinit
-
-// Constants for field numbers of messages declared in descriptor.proto.
-const (
-	// FileDescriptorProto field numbers
-	fileDesc_Syntax        = 12 // optional string
-	fileDesc_Name          = 1  // optional string
-	fileDesc_Package       = 2  // optional string
-	fileDesc_Imports       = 3  // repeated string
-	fileDesc_PublicImports = 10 // repeated int32
-	fileDesc_WeakImports   = 11 // repeated int32
-	fileDesc_Enums         = 5  // repeated EnumDescriptorProto
-	fileDesc_Messages      = 4  // repeated DescriptorProto
-	fileDesc_Extensions    = 7  // repeated FieldDescriptorProto
-	fileDesc_Services      = 6  // repeated ServiceDescriptorProto
-	fileDesc_Options       = 8  // optional FileOptions
-
-	// EnumDescriptorProto field numbers
-	enumDesc_Name           = 1 // optional string
-	enumDesc_Values         = 2 // repeated EnumValueDescriptorProto
-	enumDesc_ReservedNames  = 5 // repeated string
-	enumDesc_ReservedRanges = 4 // repeated EnumReservedRange
-	enumDesc_Options        = 3 // optional EnumOptions
-
-	// EnumReservedRange field numbers
-	enumReservedRange_Start = 1 // optional int32
-	enumReservedRange_End   = 2 // optional int32
-
-	// EnumValueDescriptorProto field numbers
-	enumValueDesc_Name    = 1 // optional string
-	enumValueDesc_Number  = 2 // optional int32
-	enumValueDesc_Options = 3 // optional EnumValueOptions
-
-	// DescriptorProto field numbers
-	messageDesc_Name            = 1  // optional string
-	messageDesc_Fields          = 2  // repeated FieldDescriptorProto
-	messageDesc_Oneofs          = 8  // repeated OneofDescriptorProto
-	messageDesc_ReservedNames   = 10 // repeated string
-	messageDesc_ReservedRanges  = 9  // repeated ReservedRange
-	messageDesc_ExtensionRanges = 5  // repeated ExtensionRange
-	messageDesc_Enums           = 4  // repeated EnumDescriptorProto
-	messageDesc_Messages        = 3  // repeated DescriptorProto
-	messageDesc_Extensions      = 6  // repeated FieldDescriptorProto
-	messageDesc_Options         = 7  // optional MessageOptions
-
-	// ReservedRange field numbers
-	messageReservedRange_Start = 1 // optional int32
-	messageReservedRange_End   = 2 // optional int32
-
-	// ExtensionRange field numbers
-	messageExtensionRange_Start   = 1 // optional int32
-	messageExtensionRange_End     = 2 // optional int32
-	messageExtensionRange_Options = 3 // optional ExtensionRangeOptions
-
-	// MessageOptions field numbers
-	messageOptions_IsMapEntry = 7 // optional bool
-
-	// FieldDescriptorProto field numbers
-	fieldDesc_Name         = 1  // optional string
-	fieldDesc_Number       = 3  // optional int32
-	fieldDesc_Cardinality  = 4  // optional Label
-	fieldDesc_Kind         = 5  // optional Type
-	fieldDesc_JSONName     = 10 // optional string
-	fieldDesc_Default      = 7  // optional string
-	fieldDesc_OneofIndex   = 9  // optional int32
-	fieldDesc_TypeName     = 6  // optional string
-	fieldDesc_ExtendedType = 2  // optional string
-	fieldDesc_Options      = 8  // optional FieldOptions
-
-	// FieldOptions field numbers
-	fieldOptions_IsPacked = 2  // optional bool
-	fieldOptions_IsWeak   = 10 // optional bool
-
-	// OneofDescriptorProto field numbers
-	oneofDesc_Name    = 1 // optional string
-	oneofDesc_Options = 2 // optional OneofOptions
-
-	// ServiceDescriptorProto field numbers
-	serviceDesc_Name    = 1 // optional string
-	serviceDesc_Methods = 2 // repeated MethodDescriptorProto
-	serviceDesc_Options = 3 // optional ServiceOptions
-
-	// MethodDescriptorProto field numbers
-	methodDesc_Name              = 1 // optional string
-	methodDesc_InputType         = 2 // optional string
-	methodDesc_OutputType        = 3 // optional string
-	methodDesc_IsStreamingClient = 5 // optional bool
-	methodDesc_IsStreamingServer = 6 // optional bool
-	methodDesc_Options           = 4 // optional MethodOptions
-)

protogen/protogen.go

@@ -29,6 +29,7 @@ import (
 	"strings"
 
 	"github.com/golang/protobuf/proto"
+	"github.com/golang/protobuf/v2/internal/descfield"
 	"github.com/golang/protobuf/v2/internal/scalar"
 	"github.com/golang/protobuf/v2/reflect/protodesc"
 	"github.com/golang/protobuf/v2/reflect/protoreflect"
@@ -519,9 +520,9 @@ type Message struct {
 func newMessage(gen *Plugin, f *File, parent *Message, desc protoreflect.MessageDescriptor) *Message {
 	var loc Location
 	if parent != nil {
-		loc = parent.Location.appendPath(messageMessageField, int32(desc.Index()))
+		loc = parent.Location.appendPath(descfield.DescriptorProto_NestedType, int32(desc.Index()))
 	} else {
-		loc = f.location(fileMessageField, int32(desc.Index()))
+		loc = f.location(descfield.FileDescriptorProto_MessageType, int32(desc.Index()))
 	}
 	message := &Message{
 		Desc:     desc,
@@ -637,11 +638,11 @@ func newField(gen *Plugin, f *File, message *Message, desc protoreflect.FieldDes
 	var loc Location
 	switch {
 	case desc.ExtendedType() != nil && message == nil:
-		loc = f.location(fileExtensionField, int32(desc.Index()))
+		loc = f.location(descfield.FileDescriptorProto_Extension, int32(desc.Index()))
 	case desc.ExtendedType() != nil && message != nil:
-		loc = message.Location.appendPath(messageExtensionField, int32(desc.Index()))
+		loc = message.Location.appendPath(descfield.DescriptorProto_Extension, int32(desc.Index()))
 	default:
-		loc = message.Location.appendPath(messageFieldField, int32(desc.Index()))
+		loc = message.Location.appendPath(descfield.DescriptorProto_Field, int32(desc.Index()))
 	}
 	field := &Field{
 		Desc:          desc,
@@ -702,7 +703,7 @@ func newOneof(gen *Plugin, f *File, message *Message, desc protoreflect.OneofDes
 		Desc:          desc,
 		ParentMessage: message,
 		GoName:        camelCase(string(desc.Name())),
-		Location:      message.Location.appendPath(messageOneofField, int32(desc.Index())),
+		Location:      message.Location.appendPath(descfield.DescriptorProto_OneofDecl, int32(desc.Index())),
 	}
 }
 
@@ -724,9 +725,9 @@ type Enum struct {
 func newEnum(gen *Plugin, f *File, parent *Message, desc protoreflect.EnumDescriptor) *Enum {
 	var loc Location
 	if parent != nil {
-		loc = parent.Location.appendPath(messageEnumField, int32(desc.Index()))
+		loc = parent.Location.appendPath(descfield.DescriptorProto_EnumType, int32(desc.Index()))
 	} else {
-		loc = f.location(fileEnumField, int32(desc.Index()))
+		loc = f.location(descfield.FileDescriptorProto_EnumType, int32(desc.Index()))
 	}
 	enum := &Enum{
 		Desc:     desc,
@@ -761,7 +762,7 @@ func newEnumValue(gen *Plugin, f *File, message *Message, enum *Enum, desc proto
 	return &EnumValue{
 		Desc:     desc,
 		GoIdent:  f.GoImportPath.Ident(name),
-		Location: enum.Location.appendPath(enumValueField, int32(desc.Index())),
+		Location: enum.Location.appendPath(descfield.EnumDescriptorProto_Value, int32(desc.Index())),
 	}
 }
 
@@ -778,7 +779,7 @@ func newService(gen *Plugin, f *File, desc protoreflect.ServiceDescriptor) *Serv
 	service := &Service{
 		Desc:     desc,
 		GoName:   camelCase(string(desc.Name())),
-		Location: f.location(fileServiceField, int32(desc.Index())),
+		Location: f.location(descfield.FileDescriptorProto_Service, int32(desc.Index())),
 	}
 	for i, mdescs := 0, desc.Methods(); i < mdescs.Len(); i++ {
 		service.Methods = append(service.Methods, newMethod(gen, f, service, mdescs.Get(i)))
@@ -802,7 +803,7 @@ func newMethod(gen *Plugin, f *File, service *Service, desc protoreflect.MethodD
 		Desc:          desc,
 		GoName:        camelCase(string(desc.Name())),
 		ParentService: service,
-		Location:      service.Location.appendPath(serviceMethodField, int32(desc.Index())),
+		Location:      service.Location.appendPath(descfield.ServiceDescriptorProto_Method, int32(desc.Index())),
 	}
 	return method
 }
@@ -1081,34 +1082,6 @@ const (
 	pathTypeSourceRelative
 )
 
-// The SourceCodeInfo message describes the location of elements of a parsed
-// .proto file by way of a "path", which is a sequence of integers that
-// describe the route from a FileDescriptorProto to the relevant submessage.
-// The path alternates between a field number of a repeated field, and an index
-// into that repeated field. The constants below define the field numbers that
-// are used.
-//
-// See descriptor.proto for more information about this.
-const (
-	// field numbers in FileDescriptorProto
-	filePackageField   = 2 // package
-	fileMessageField   = 4 // message_type
-	fileEnumField      = 5 // enum_type
-	fileServiceField   = 6 // service
-	fileExtensionField = 7 // extension
-	// field numbers in DescriptorProto
-	messageFieldField     = 2 // field
-	messageMessageField   = 3 // nested_type
-	messageEnumField      = 4 // enum_type
-	messageExtensionField = 6 // extension
-	messageOneofField     = 8 // oneof_decl
-	// field numbers in EnumDescriptorProto
-	enumValueField = 2 // value
-	// field numbers in ServiceDescriptorProto
-	serviceMethodField = 2 // method
-	serviceStreamField = 4 // stream
-)
-
 // A Location is a location in a .proto source file.
 //
 // See the google.protobuf.SourceCodeInfo documentation in descriptor.proto