Always treat groups as message fields (#132)

The relative simplicity and obviousness of this fix greatly obscures how
difficult it was to determine :)

Protobuf editions adds a couple "new" features to protobuf that cleverly
re-use old protobuf wire and language features.

In case of expanded repeated field representation, there appears to be
no difference: for repeated fields, protobuf already supported both wire
encodings, and protoreflect already had to treat them the same. Thus,
repeated fields with both encodings work fine with protovalidate-go.

In case of delimited message representation, this uses the old proto2
group encoding. This almost works, because protoreflect treats groups
and submessage fields very similarly, and some of the protovalidate-go
code also already handles groups as expected.

Unfortunately though, there were a few places where groups and messages
were not being treated identically. The failure case is rather obscure:
_almost_ everything works, but some special cases are not taken
correctly with the group encoding. This in and of itself is not
automatically a problem but it can lead to weird issues, most notably
the subtype not being discovered and registered correctly in the dynamic
case.

Although I did not individually test each line change to make sure that
it fixes a specific bug, most of these are definitely needed and fix
behavioral issues, except I am not 100% sure about the pgv migrator
(Probably unnecessary but if proto2 groups work in pgv it seems fine for
good measure.) I will make a separate PR to protovalidate that includes
plenty of new test cases that ensure editions works; most of these pass
on `main` save for some of the delimited submessage ones.

cel-go seems to behave correctly already. I initially suspected a
problem with how it handled delimited submessages, but it was a red
herring.

Makefile

@@ -16,7 +16,7 @@ GOLANGCI_LINT_VERSION ?= v1.59.1
 # Set to use a different version of protovalidate-conformance.
 # Should be kept in sync with the version referenced in proto/buf.lock and
 # 'buf.build/gen/go/bufbuild/protovalidate/protocolbuffers/go' in go.mod.
-CONFORMANCE_VERSION ?= v0.6.3
+CONFORMANCE_VERSION ?= v0.7.1
 
 .PHONY: help
 help: ## Describe useful make targets

buf.lock

@@ -2,11 +2,11 @@
 version: v2
 deps:
   - name: buf.build/bufbuild/protovalidate
-    commit: b983156c5e994cc9892e0ce3e64e17e0
-    digest: b5:a02a4a5a0a9306cf1391d17e8811bbd6a0dbd0e0e29ddfc34b9d103311164974472d43627c3d63e6a8abaffd6c7a301c4f7965bbab2dc56f7f7812429a84b812
+    commit: a6c49f84cc0f4e038680d390392e2ab0
+    digest: b5:e968392e88ff7915adcbd1635d670b45bff8836ec2415d81fc559ca5470a695dbdc30030bad8bc5764647c731079e9e7bba0023ea25c4e4a1672a7d2561d4a19
   - name: buf.build/bufbuild/protovalidate-testing
-    commit: 09d8555b907f4bfa9e784469b66e2bea
-    digest: b5:de77b29bc5e88cfa2b0b1fa7b0e12f33d77aefca2821f465c5a54b77696e20919ffb7981cc90ceff41d0a3aab761457030056460bf20129b2dacae5cdcbe21b7
+    commit: 7c0e0340f14c4d6580c200dcaa9b00d0
+    digest: b5:f0dacc3a02e3fcd277c3516cd0089e69478374b5ad15fe1032853789668d1d660cac4c6e1776799a66b251b9583ddc320e9db91acf6e8681e31d76ccc1f22ea3
   - name: buf.build/envoyproxy/protoc-gen-validate
-    commit: 71881f09a0c5420a9545a07987a86728
-    digest: b5:e8a034a81f1d6218f712879269bedac768c9e39452d7a92f83d70923fcd6aa9eb02c81ff6ff337cd0dd9b9fe719d6c4459e655f662ae7112aaa1c2110992afd0
+    commit: daf171c6cdb54629b5f51e345a79e4dd
+    digest: b5:c745e1521879f43740230b1df673d0729f55704efefdcfc489d4a0a2d40c92a26cacfeab62813403040a8b180142d53b398c7ca784a065e43823605ee49681de

celext/lib.go

@@ -61,7 +61,8 @@ func RequiredCELEnvOptions(fieldDesc protoreflect.FieldDescriptor) []cel.EnvOpti
 			RequiredCELEnvOptions(fieldDesc.MapValue())...,
 		)
 	}
-	if fieldDesc.Kind() == protoreflect.MessageKind {
+	if fieldDesc.Kind() == protoreflect.MessageKind ||
+		fieldDesc.Kind() == protoreflect.GroupKind {
 		return []cel.EnvOption{
 			cel.Types(dynamicpb.NewMessage(fieldDesc.Message())),
 		}

celext/lookups.go

@@ -42,7 +42,8 @@ func ProtoFieldToCELType(fieldDesc protoreflect.FieldDescriptor, generic, forIte
 		}
 	}
 
-	if fieldDesc.Kind() == protoreflect.MessageKind {
+	if fieldDesc.Kind() == protoreflect.MessageKind ||
+		fieldDesc.Kind() == protoreflect.GroupKind {
 		switch fqn := fieldDesc.Message().FullName(); fqn {
 		case "google.protobuf.Any":
 			return cel.AnyType

internal/constraints/cache.go

@@ -161,7 +161,8 @@ func (c *Cache) getExpectedConstraintDescriptor(
 		return mapFieldConstraintsDesc, true
 	case targetFieldDesc.IsList() && !forItems:
 		return repeatedFieldConstraintsDesc, true
-	case targetFieldDesc.Kind() == protoreflect.MessageKind:
+	case targetFieldDesc.Kind() == protoreflect.MessageKind,
+		targetFieldDesc.Kind() == protoreflect.GroupKind:
 		expected, ok = expectedWKTConstraints[targetFieldDesc.Message().FullName()]
 		return expected, ok
 	default:

internal/evaluator/builder.go

@@ -301,7 +301,7 @@ func (bldr *Builder) processEmbeddedMessage(
 	valEval *value,
 	cache MessageCache,
 ) error {
-	if fdesc.Kind() != protoreflect.MessageKind ||
+	if !isMessageField(fdesc) ||
 		bldr.shouldSkip(rules) ||
 		fdesc.IsMap() ||
 		(fdesc.IsList() && !forItems) {
@@ -326,7 +326,7 @@ func (bldr *Builder) processWrapperConstraints(
 	valEval *value,
 	cache MessageCache,
 ) error {
-	if fdesc.Kind() != protoreflect.MessageKind ||
+	if !isMessageField(fdesc) ||
 		bldr.shouldSkip(rules) ||
 		fdesc.IsMap() ||
 		(fdesc.IsList() && !forItems) {
@@ -374,7 +374,7 @@ func (bldr *Builder) processAnyConstraints(
 	_ MessageCache,
 ) error {
 	if (fdesc.IsList() && !forItems) ||
-		fdesc.Kind() != protoreflect.MessageKind ||
+		!isMessageField(fdesc) ||
 		fdesc.Message().FullName() != "google.protobuf.Any" {
 		return nil
 	}
@@ -488,7 +488,7 @@ func (bldr *Builder) zeroValue(fdesc protoreflect.FieldDescriptor, forItems bool
 	case forItems && fdesc.IsList():
 		msg := dynamicpb.NewMessage(fdesc.ContainingMessage())
 		return msg.Get(fdesc).List().NewElement()
-	case fdesc.Kind() == protoreflect.MessageKind &&
+	case isMessageField(fdesc) &&
 		fdesc.Cardinality() != protoreflect.Repeated:
 		msg := dynamicpb.NewMessage(fdesc.Message())
 		return protoreflect.ValueOfMessage(msg)
@@ -509,3 +509,14 @@ func (c MessageCache) SyncTo(other MessageCache) {
 		other[k] = v
 	}
 }
+
+// isMessageField returns true if the field descriptor fdesc describes a field
+// containing a submessage. Although they are represented differently on the
+// wire, group fields are treated like message fields in protoreflect and have
+// similar properties. In the 2023 edition of protobuf, message fields with the
+// delimited encoding feature will be detected as groups, but should otherwise
+// be treated the same.
+func isMessageField(fdesc protoreflect.FieldDescriptor) bool {
+	return fdesc.Kind() == protoreflect.MessageKind ||
+		fdesc.Kind() == protoreflect.GroupKind
+}