Update descriptor implementations to work with editions (bufbuild#260)

This updates this library to use the latest protobuf-go, which provides
support for representing Editions source files via
`protoreflect.FileDescriptor`. It also updates the implementations of
`protoreflect.Descriptor` in this module to properly utilize editions
features to implement the semantic accessors
`FieldDescriptor.HasPresence`, `FieldDescriptor.IsPacked`, and the
newly-added `EnumDescriptor.IsClosed`. All other conditionals
that previously examined syntax have now been updated to be
editions-aware.

(cherry picked from commit 3024677)

.protoc_version

@@ -1 +1 @@
-25.0-rc2
+26.0

Makefile

@@ -144,9 +144,12 @@ internal/testdata/desc_test_defaults.protoset: $(PROTOC) internal/testdata/desc_
 internal/testdata/desc_test_proto3_optional.protoset: $(PROTOC) internal/testdata/desc_test_proto3_optional.proto
 	cd $(@D) && $(PROTOC) --descriptor_set_out=$(@F) --include_imports -I. $(filter-out protoc,$(^F))
 
-internal/testdata/descriptor_impl_tests.protoset: $(PROTOC) internal/testdata/desc_test2.proto internal/testdata/desc_test_defaults.proto internal/testdata/desc_test_proto3.proto internal/testdata/desc_test_proto3_optional.proto
+internal/testdata/descriptor_impl_tests.protoset: $(PROTOC) internal/testdata/desc_test2.proto internal/testdata/desc_test_complex.proto internal/testdata/desc_test_defaults.proto internal/testdata/desc_test_proto3.proto internal/testdata/desc_test_proto3_optional.proto
 	cd $(@D) && $(PROTOC) --descriptor_set_out=$(@F) --include_imports -I. $(filter-out protoc,$(^F))
 
+internal/testdata/descriptor_editions_impl_tests.protoset: $(PROTOC) internal/testdata/editions/all_default_features.proto internal/testdata/editions/features_with_overrides.proto
+	cd $(@D)/editions && $(PROTOC) --experimental_editions --descriptor_set_out=../$(@F) --include_imports -I. $(filter-out protoc,$(^F))
+
 internal/testdata/editions/all.protoset: $(PROTOC) $(sort $(wildcard internal/testdata/editions/*.proto))
 	cd $(@D) && $(PROTOC) --experimental_editions --descriptor_set_out=$(@F) --include_imports -I. $(filter-out protoc,$(^F))
 
@@ -171,6 +174,7 @@ test-descriptors: internal/testdata/desc_test_complex.protoset
 test-descriptors: internal/testdata/desc_test_defaults.protoset
 test-descriptors: internal/testdata/desc_test_proto3_optional.protoset
 test-descriptors: internal/testdata/descriptor_impl_tests.protoset
+test-descriptors: internal/testdata/descriptor_editions_impl_tests.protoset
 test-descriptors: internal/testdata/editions/all.protoset
 test-descriptors: internal/testdata/source_info.protoset
 test-descriptors: internal/testdata/options/test.protoset

go.mod

@@ -8,7 +8,7 @@ require (
 	github.com/plar/go-adaptive-radix-tree v1.0.5
 	github.com/stretchr/testify v1.8.4
 	golang.org/x/sync v0.6.0
-	google.golang.org/protobuf v1.33.0
+	google.golang.org/protobuf v1.33.1-0.20240319125436-3039476726e4
 )
 
 require (

go.sum

@@ -26,8 +26,8 @@ github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcU
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 golang.org/x/sync v0.6.0 h1:5BMeUDZ7vkXGfEr1x9B4bRcTH4lpkTkpdh0T/J+qjbQ=
 golang.org/x/sync v0.6.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
-google.golang.org/protobuf v1.33.0 h1:uNO2rsAINq/JlFpSdYEKIZ0uKD/R9cpdv0T+yoGwGmI=
-google.golang.org/protobuf v1.33.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=
+google.golang.org/protobuf v1.33.1-0.20240319125436-3039476726e4 h1:fea3X9JPnW4oM9z1ctAuAN7kAnM/YbdI7QHCZXKLVMk=
+google.golang.org/protobuf v1.33.1-0.20240319125436-3039476726e4/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=

internal/benchmarks/go.mod

@@ -1,20 +1,22 @@
 module github.com/kralicky/protocompile/internal/benchmarks
 
-go 1.22
+go 1.22.0
 
 require (
 	github.com/igrmk/treemap/v2 v2.0.1
 	github.com/jhump/protoreflect v1.14.1 // MUST NOT be updated to v1.15 or higher
 	github.com/kralicky/protocompile v0.0.0
 	github.com/stretchr/testify v1.8.4
-	google.golang.org/protobuf v1.32.0
+	google.golang.org/protobuf v1.33.1-0.20240319125436-3039476726e4
 )
 
 require golang.org/x/sync v0.6.0
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/golang/protobuf v1.5.0 // indirect
+	github.com/golang/protobuf v1.5.4 // indirect
+	github.com/kr/pretty v0.2.1 // indirect
+	github.com/kralicky/codegen v0.0.0-20240307225947-51de80fcb2f3 // indirect
 	github.com/plar/go-adaptive-radix-tree v1.0.5 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	golang.org/x/exp v0.0.0-20220317015231-48e79f11773a // indirect

internal/benchmarks/go.sum

@@ -1,5 +1,6 @@
 cloud.google.com/go v0.26.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/bufbuild/protocompile v0.9.0 h1:DI8qLG5PEO0Mu1Oj51YFPqtx6I3qYXUAhJVJ/IzAVl0=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
 github.com/cncf/udpa/go v0.0.0-20201120205902-5459f2c99403/go.mod h1:WmhPx2Nbnhtbo57+VJT5O0JRkEi1Wbu0z5j0R8u5Hbk=
@@ -21,8 +22,9 @@ github.com/golang/protobuf v1.4.0-rc.4.0.20200313231945-b860323f09d0/go.mod h1:W
 github.com/golang/protobuf v1.4.0/go.mod h1:jodUvKwWbYaEsadDk5Fwe5c77LiNKVO9IDvqG2KuDX0=
 github.com/golang/protobuf v1.4.1/go.mod h1:U8fpvMrcmy5pZrNK1lt4xCsGvpyWQ/VVv6QDs8UjoX8=
 github.com/golang/protobuf v1.4.2/go.mod h1:oDoupMAO8OvCJWAcko0GGGIgR6R6ocIYbsSw735rRwI=
-github.com/golang/protobuf v1.5.0 h1:LUVKkCeviFUMKqHa4tXIIij/lbhnMbP7Fn5wKdKkRh4=
 github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
+github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=
+github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
 github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
 github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
@@ -40,12 +42,13 @@ github.com/jhump/goprotoc v0.5.0/go.mod h1:VrbvcYrQOrTi3i0Vf+m+oqQWk9l72mjkJCYo7
 github.com/jhump/protoreflect v1.11.0/go.mod h1:U7aMIjN0NWq9swDP7xDdoMfRHb35uiuTd3Z9nFXJf5E=
 github.com/jhump/protoreflect v1.14.1 h1:N88q7JkxTHWFEqReuTsYH1dPIwXxA0ITNQp7avLY10s=
 github.com/jhump/protoreflect v1.14.1/go.mod h1:JytZfP5d0r8pVNLZvai7U/MCuTWITgrI4tTg7puQFKI=
-github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/pretty v0.2.1 h1:Fmg33tUaq4/8ym9TJN1x7sLJnHVwhP33CNkpYV/7rwI=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/kralicky/codegen v0.0.0-20240307225947-51de80fcb2f3 h1:BWm3t2mZaeu4hgH1Zr4OSllcrgyKyZDcHv5emWjaB8Y=
 github.com/plar/go-adaptive-radix-tree v1.0.5 h1:rHR89qy/6c24TBAHullFMrJsU9hGlKmPibdBGU6/gbM=
 github.com/plar/go-adaptive-radix-tree v1.0.5/go.mod h1:15VOUO7R9MhJL8HOJdpydR0rvanrtRE6fA6XSa/tqWE=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
@@ -122,8 +125,8 @@ google.golang.org/protobuf v1.23.1-0.20200526195155-81db48ad09cc/go.mod h1:EGpAD
 google.golang.org/protobuf v1.25.0/go.mod h1:9JNX74DMeImyA3h4bdi1ymwjUzf21/xIlbajtzgsN7c=
 google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
 google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
-google.golang.org/protobuf v1.32.0 h1:pPC6BG5ex8PDFnkbrGU3EixyhKcQ2aDuBS36lqK/C7I=
-google.golang.org/protobuf v1.32.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=
+google.golang.org/protobuf v1.33.1-0.20240319125436-3039476726e4 h1:fea3X9JPnW4oM9z1ctAuAN7kAnM/YbdI7QHCZXKLVMk=
+google.golang.org/protobuf v1.33.1-0.20240319125436-3039476726e4/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=

internal/testdata/editions/features_with_overrides.proto

@@ -13,9 +13,20 @@ message Foo {
   int32               def = 3;
   repeated bool       ghi = 4 [features.repeated_field_encoding = EXPANDED];
   map<string, string> jkl = 5 [features.utf8_validation = NONE];
-  Bar                 mno = 6 [features.message_encoding = DELIMITED];
-  repeated double     pqr = 7;
-  map<string, Bar>    stu = 8;
+  // TODO: A bug in the protobuf-go runtime prevents it from processing
+  //       this field. The "delimited" encoding appears to trigger
+  //       proto2 group validation rules, so it requires that the
+  //       message type be a nested message in the same scope and be
+  //       named the same as the field, but with initial capital letter.
+  //       So we instead have to use a type that makes it happy...
+  //       https://github.com/golang/protobuf/issues/1603
+  //Bar mno = 6 [features.message_encoding = DELIMITED];
+  Mno mno = 6 [features.message_encoding = DELIMITED];
+  message Mno {
+    bytes other = 1;
+  }
+  repeated double pqr = 7;
+  map<string, Bar> stu = 8;
 }
 
 message Bar {

internal/tools/go.mod

@@ -67,7 +67,7 @@ require (
 	github.com/gobwas/glob v0.2.3 // indirect
 	github.com/gofrs/flock v0.8.1 // indirect
 	github.com/gofrs/uuid/v5 v5.0.0 // indirect
-	github.com/golang/protobuf v1.5.3 // indirect
+	github.com/golang/protobuf v1.5.4 // indirect
 	github.com/golangci/check v0.0.0-20180506172741-cfe4005ccda2 // indirect
 	github.com/golangci/dupl v0.0.0-20180902072040-3e9179ac440a // indirect
 	github.com/golangci/go-misc v0.0.0-20220329215616-d24fe342adfe // indirect
@@ -188,7 +188,7 @@ require (
 	golang.org/x/sync v0.6.0 // indirect
 	golang.org/x/sys v0.14.0 // indirect
 	golang.org/x/text v0.14.0 // indirect
-	google.golang.org/protobuf v1.32.0 // indirect
+	google.golang.org/protobuf v1.33.0 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect

internal/tools/go.sum

@@ -225,8 +225,8 @@ github.com/golang/protobuf v1.4.2/go.mod h1:oDoupMAO8OvCJWAcko0GGGIgR6R6ocIYbsSw
 github.com/golang/protobuf v1.4.3/go.mod h1:oDoupMAO8OvCJWAcko0GGGIgR6R6ocIYbsSw735rRwI=
 github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
 github.com/golang/protobuf v1.5.2/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
-github.com/golang/protobuf v1.5.3 h1:KhyjKVUg7Usr/dYsdSqoFveMYd5ko72D+zANwlG1mmg=
-github.com/golang/protobuf v1.5.3/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
+github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=
+github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
 github.com/golangci/check v0.0.0-20180506172741-cfe4005ccda2 h1:23T5iq8rbUYlhpt5DB4XJkc6BU31uODLD1o1gKvZmD0=
 github.com/golangci/check v0.0.0-20180506172741-cfe4005ccda2/go.mod h1:k9Qvh+8juN+UKMCS/3jFtGICgW8O96FVaZsaxdzDkR4=
 github.com/golangci/dupl v0.0.0-20180902072040-3e9179ac440a h1:w8hkcTqaFpzKqonE9uMCefW1WDie15eSP/4MssdenaM=
@@ -962,8 +962,8 @@ google.golang.org/protobuf v1.24.0/go.mod h1:r/3tXBNzIEhYS9I1OUVjXDlt8tc493IdKGj
 google.golang.org/protobuf v1.25.0/go.mod h1:9JNX74DMeImyA3h4bdi1ymwjUzf21/xIlbajtzgsN7c=
 google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
 google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
-google.golang.org/protobuf v1.32.0 h1:pPC6BG5ex8PDFnkbrGU3EixyhKcQ2aDuBS36lqK/C7I=
-google.golang.org/protobuf v1.32.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=
+google.golang.org/protobuf v1.33.0 h1:uNO2rsAINq/JlFpSdYEKIZ0uKD/R9cpdv0T+yoGwGmI=
+google.golang.org/protobuf v1.33.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=
 gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

linker/descriptors.go

@@ -219,11 +219,26 @@ func (r *result) Syntax() protoreflect.Syntax {
 		return protoreflect.Proto2
 	case "proto3":
 		return protoreflect.Proto3
+	case "editions":
+		return protoreflect.Editions
 	default:
 		return 0 // ???
 	}
 }
 
+func (r *result) Edition() int32 {
+	switch r.Syntax() {
+	case protoreflect.Proto2:
+		return int32(descriptorpb.Edition_EDITION_PROTO2)
+	case protoreflect.Proto3:
+		return int32(descriptorpb.Edition_EDITION_PROTO3)
+	case protoreflect.Editions:
+		return int32(r.FileDescriptorProto().GetEdition())
+	default:
+		return int32(descriptorpb.Edition_EDITION_UNKNOWN) // ???
+	}
+}
+
 func (r *result) Name() protoreflect.Name {
 	return ""
 }
@@ -1005,6 +1020,11 @@ func (e *enumDescriptor) ReservedRanges() protoreflect.EnumRanges {
 	return e.rsvdRanges
 }
 
+func (e *enumDescriptor) IsClosed() bool {
+	enumType := resolveFeature(e, enumTypeField)
+	return descriptorpb.FeatureSet_EnumType(enumType.Enum()) == descriptorpb.FeatureSet_CLOSED
+}
+
 type enumRanges struct {
 	protoreflect.EnumRanges
 	ranges [][2]protoreflect.EnumNumber
@@ -1327,6 +1347,12 @@ func (f *fldDescriptor) Cardinality() protoreflect.Cardinality {
 }
 
 func (f *fldDescriptor) Kind() protoreflect.Kind {
+	if f.proto.GetType() == descriptorpb.FieldDescriptorProto_TYPE_MESSAGE && f.Syntax() == protoreflect.Editions {
+		messageEncoding := resolveFeature(f, messageEncodingField)
+		if descriptorpb.FeatureSet_MessageEncoding(messageEncoding.Enum()) == descriptorpb.FeatureSet_DELIMITED {
+			return protoreflect.GroupKind
+		}
+	}
 	return protoreflect.Kind(f.proto.GetType())
 }
 
@@ -1352,10 +1378,13 @@ func (f *fldDescriptor) HasPresence() bool {
 	if f.proto.GetLabel() == descriptorpb.FieldDescriptorProto_LABEL_REPEATED {
 		return false
 	}
-	return f.IsExtension() ||
-		f.Syntax() == protoreflect.Proto2 ||
+	if f.IsExtension() ||
 		f.Kind() == protoreflect.MessageKind || f.Kind() == protoreflect.GroupKind ||
-		f.proto.OneofIndex != nil
+		f.proto.OneofIndex != nil {
+		return true
+	}
+	fieldPresence := descriptorpb.FeatureSet_FieldPresence(resolveFeature(f, fieldPresenceField).Enum())
+	return fieldPresence == descriptorpb.FeatureSet_EXPLICIT || fieldPresence == descriptorpb.FeatureSet_LEGACY_REQUIRED
 }
 
 func (f *fldDescriptor) IsExtension() bool {
@@ -1382,30 +1411,16 @@ func (f *fldDescriptor) IsWeak() bool {
 }
 
 func (f *fldDescriptor) IsPacked() bool {
-	opts := f.proto.GetOptions()
-	if opts.GetPacked() {
-		return true
-	}
-	if opts != nil && opts.Packed != nil {
-		// explicitly not packed
-		return false
-	}
-
-	// proto3 defaults to packed for repeated scalar numeric fields
-	if f.file.Syntax() != protoreflect.Proto3 {
-		return false
-	}
-	if f.proto.GetLabel() != descriptorpb.FieldDescriptorProto_LABEL_REPEATED {
+	if f.Cardinality() != protoreflect.Repeated || !protointernal.CanPack(f.Kind()) {
 		return false
 	}
-	switch f.proto.GetType() {
-	case descriptorpb.FieldDescriptorProto_TYPE_GROUP, descriptorpb.FieldDescriptorProto_TYPE_MESSAGE,
-		descriptorpb.FieldDescriptorProto_TYPE_BYTES, descriptorpb.FieldDescriptorProto_TYPE_STRING:
-		return false
-	default:
-		// all others can be packed
-		return true
+	opts := f.proto.GetOptions()
+	if opts != nil && opts.Packed != nil {
+		// packed option is set explicitly
+		return *opts.Packed
 	}
+	fieldEncoding := resolveFeature(f, repeatedFieldEncodingField)
+	return descriptorpb.FeatureSet_RepeatedFieldEncoding(fieldEncoding.Enum()) == descriptorpb.FeatureSet_PACKED
 }
 
 func (f *fldDescriptor) IsList() bool {