internal/pkgbits: add DerivedInfoNeeded

So next CL can use it to remove unnecessary derivedInfo needed field.

Updates #68778

Change-Id: Ia4e0f638beaf4a448fbf10a9aa1bc9425349a5e8
Reviewed-on: https://go-review.googlesource.com/c/go/+/608215
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Tim King <taking@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/internal/pkgbits/pkgbits_test.go

@@ -45,6 +45,8 @@ func TestVersions(t *testing.T) {
 		{pkgbits.V1, pkgbits.HasInit},
 		{pkgbits.V0, pkgbits.DerivedFuncInstance},
 		{pkgbits.V1, pkgbits.DerivedFuncInstance},
+		{pkgbits.V0, pkgbits.DerivedInfoNeeded},
+		{pkgbits.V1, pkgbits.DerivedInfoNeeded},
 		{pkgbits.V2, pkgbits.AliasTypeParamNames},
 	} {
 		if !c.v.Has(c.f) {
@@ -57,6 +59,7 @@ func TestVersions(t *testing.T) {
 		{pkgbits.V0, pkgbits.Flags},
 		{pkgbits.V2, pkgbits.HasInit},
 		{pkgbits.V2, pkgbits.DerivedFuncInstance},
+		{pkgbits.V2, pkgbits.DerivedInfoNeeded},
 		{pkgbits.V0, pkgbits.AliasTypeParamNames},
 		{pkgbits.V1, pkgbits.AliasTypeParamNames},
 	} {

src/internal/pkgbits/version.go

@@ -25,6 +25,7 @@ const (
 	// - remove the legacy "has init" bool from the public root
 	// - remove obj's "derived func instance" bool
 	// - add a TypeParamNames field to ObjAlias
+	// - remove derived info "needed" bool
 	V2
 
 	numVersions = iota
@@ -56,6 +57,10 @@ const (
 	// ObjAlias has a list of TypeParamNames.
 	AliasTypeParamNames
 
+	// Deprecated: DerivedInfoNeeded was a bool indicating
+	// whether a type was a derived type.
+	DerivedInfoNeeded
+
 	numFields = iota
 )
 
@@ -71,6 +76,7 @@ var introduced = [numFields]Version{
 var removed = [numFields]Version{
 	HasInit:             V2,
 	DerivedFuncInstance: V2,
+	DerivedInfoNeeded:   V2,
 }
 
 // Has reports whether field f is present in a bitstream at version v.