Allow overrides for TARGET_BUILD_VARIANT am: 9ef6edba2c

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/3349197

Change-Id: I106eef525bc717f57d1162c27e6cbbda903d00f0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
diff --git a/cmd/release_config/release_config_lib/release_config.go b/cmd/release_config/release_config_lib/release_config.go
index 3c834cc..8d21002 100644
--- a/cmd/release_config/release_config_lib/release_config.go
+++ b/cmd/release_config/release_config_lib/release_config.go
@@ -85,6 +85,16 @@
 	// Prior stage(s) for flag advancement (during development).
 	// Once a flag has met criteria in a prior stage, it can advance to this one.
 	PriorStagesMap map[string]bool
+
+	// What type of release config is this?  This should never be
+	// ReleaseConfigType_CONFIG_TYPE_UNSPECIFIED.
+	ReleaseConfigType rc_proto.ReleaseConfigType
+}
+
+// If true, this ReleaseConfigType may only inherit from a ReleaseConfig of the
+// same ReleaseConfigType.
+var ReleaseConfigInheritanceDenyMap = map[rc_proto.ReleaseConfigType]bool{
+	rc_proto.ReleaseConfigType_BUILD_VARIANT: true,
 }
 
 func ReleaseConfigFactory(name string, index int) (c *ReleaseConfig) {
@@ -97,6 +107,10 @@
 }
 
 func (config *ReleaseConfig) InheritConfig(iConfig *ReleaseConfig) error {
+	if config.ReleaseConfigType != iConfig.ReleaseConfigType && ReleaseConfigInheritanceDenyMap[config.ReleaseConfigType] {
+		return fmt.Errorf("Release config %s (type '%s') cannot inherit from %s (type '%s')",
+			config.Name, config.ReleaseConfigType, iConfig.Name, iConfig.ReleaseConfigType)
+	}
 	for f := range iConfig.FilesUsedMap {
 		config.FilesUsedMap[f] = true
 	}
@@ -154,10 +168,10 @@
 	contributionsToApply := []*ReleaseConfigContribution{}
 	myInherits := []string{}
 	myInheritsSet := make(map[string]bool)
-	// If there is a "root" release config, it is the start of every inheritance chain.
-	_, err = configs.GetReleaseConfig("root")
-	if err == nil && !isRoot {
-		config.InheritNames = append([]string{"root"}, config.InheritNames...)
+	if config.ReleaseConfigType == rc_proto.ReleaseConfigType_RELEASE_CONFIG {
+		if _, err = configs.GetReleaseConfigStrict("root"); err == nil {
+			config.InheritNames = append([]string{"root"}, config.InheritNames...)
+		}
 	}
 	for _, inherit := range config.InheritNames {
 		if _, ok := myInheritsSet[inherit]; ok {
@@ -272,6 +286,36 @@
 			}
 		}
 	}
+
+	if config.ReleaseConfigType == rc_proto.ReleaseConfigType_RELEASE_CONFIG {
+		inheritBuildVariant := func() error {
+			build_variant := os.Getenv("TARGET_BUILD_VARIANT")
+			if build_variant == "" || config.Name == build_variant {
+				return nil
+			}
+			variant, err := configs.GetReleaseConfigStrict(build_variant)
+			if err != nil {
+				// Failure to find the build-variant release config is
+				// not an error.
+				return nil
+			}
+			if variant.ReleaseConfigType != rc_proto.ReleaseConfigType_BUILD_VARIANT {
+				return nil
+			}
+			if err = variant.GenerateReleaseConfig(configs); err != nil {
+				return err
+			}
+			return config.InheritConfig(variant)
+		}
+
+		useVariant, ok := config.FlagArtifacts["RELEASE_BUILD_USE_VARIANT_FLAGS"]
+		if ok && MarshalValue(useVariant.Value) != "" {
+			if err = inheritBuildVariant(); err != nil {
+				return err
+			}
+		}
+	}
+
 	// Now remove any duplicates from the actual value of RELEASE_ACONFIG_VALUE_SETS
 	myAconfigValueSets := []string{}
 	myAconfigValueSetsMap := map[string]bool{}
@@ -345,11 +389,12 @@
 			}
 			return ret
 		}(),
-		AconfigValueSets: myAconfigValueSets,
-		Inherits:         myInherits,
-		Directories:      directories,
-		ValueDirectories: valueDirectories,
-		PriorStages:      SortedMapKeys(config.PriorStagesMap),
+		AconfigValueSets:  myAconfigValueSets,
+		Inherits:          myInherits,
+		Directories:       directories,
+		ValueDirectories:  valueDirectories,
+		PriorStages:       SortedMapKeys(config.PriorStagesMap),
+		ReleaseConfigType: config.ReleaseConfigType.Enum(),
 	}
 
 	config.compileInProgress = false
diff --git a/cmd/release_config/release_config_lib/release_configs.go b/cmd/release_config/release_config_lib/release_configs.go
index f947b7f..f616230 100644
--- a/cmd/release_config/release_config_lib/release_configs.go
+++ b/cmd/release_config/release_config_lib/release_configs.go
@@ -361,10 +361,22 @@
 		if fmt.Sprintf("%s.textproto", name) != filepath.Base(path) {
 			return fmt.Errorf("%s incorrectly declares release config %s", path, name)
 		}
+		releaseConfigType := releaseConfigContribution.proto.ReleaseConfigType
+		if releaseConfigType == nil {
+			if name == "root" {
+				releaseConfigType = rc_proto.ReleaseConfigType_EXPLICIT_INHERITANCE_CONFIG.Enum()
+			} else {
+				releaseConfigType = rc_proto.ReleaseConfigType_RELEASE_CONFIG.Enum()
+			}
+		}
 		if _, ok := configs.ReleaseConfigs[name]; !ok {
 			configs.ReleaseConfigs[name] = ReleaseConfigFactory(name, ConfigDirIndex)
+			configs.ReleaseConfigs[name].ReleaseConfigType = *releaseConfigType
 		}
 		config := configs.ReleaseConfigs[name]
+		if config.ReleaseConfigType != *releaseConfigType {
+			return fmt.Errorf("%s mismatching ReleaseConfigType value %s", path, *releaseConfigType)
+		}
 		config.FilesUsedMap[path] = true
 		inheritNames := make(map[string]bool)
 		for _, inh := range config.InheritNames {
diff --git a/cmd/release_config/release_config_proto/build_flags_out.pb.go b/cmd/release_config/release_config_proto/build_flags_out.pb.go
index 60ba2e1..ec07415 100644
--- a/cmd/release_config/release_config_proto/build_flags_out.pb.go
+++ b/cmd/release_config/release_config_proto/build_flags_out.pb.go
@@ -235,6 +235,8 @@
 	// config.  The listed directories contain at least a `release_config` message
 	// for this release config.
 	ValueDirectories []string `protobuf:"bytes,8,rep,name=value_directories,json=valueDirectories" json:"value_directories,omitempty"`
+	// The ReleaseConfigType of this release config.
+	ReleaseConfigType *ReleaseConfigType `protobuf:"varint,9,opt,name=release_config_type,json=releaseConfigType,enum=android.release_config_proto.ReleaseConfigType" json:"release_config_type,omitempty"`
 }
 
 func (x *ReleaseConfigArtifact) Reset() {
@@ -325,6 +327,13 @@
 	return nil
 }
 
+func (x *ReleaseConfigArtifact) GetReleaseConfigType() ReleaseConfigType {
+	if x != nil && x.ReleaseConfigType != nil {
+		return *x.ReleaseConfigType
+	}
+	return ReleaseConfigType_CONFIG_TYPE_UNSPECIFIED
+}
+
 type ReleaseConfigsArtifact struct {
 	state         protoimpl.MessageState
 	sizeCache     protoimpl.SizeCache
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+	0x5f, 0x63, 0x6f, 0x6e, 0x66, 0x69, 0x67, 0x5f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x2e, 0x52, 0x65,
+	0x6c, 0x65, 0x61, 0x73, 0x65, 0x43, 0x6f, 0x6e, 0x66, 0x69, 0x67, 0x4d, 0x61, 0x70, 0x52, 0x05,
+	0x76, 0x61, 0x6c, 0x75, 0x65, 0x3a, 0x02, 0x38, 0x01, 0x42, 0x33, 0x5a, 0x31, 0x61, 0x6e, 0x64,
+	0x72, 0x6f, 0x69, 0x64, 0x2f, 0x73, 0x6f, 0x6f, 0x6e, 0x67, 0x2f, 0x72, 0x65, 0x6c, 0x65, 0x61,
+	0x73, 0x65, 0x5f, 0x63, 0x6f, 0x6e, 0x66, 0x69, 0x67, 0x2f, 0x72, 0x65, 0x6c, 0x65, 0x61, 0x73,
+	0x65, 0x5f, 0x63, 0x6f, 0x6e, 0x66, 0x69, 0x67, 0x5f, 0x70, 0x72, 0x6f, 0x74, 0x6f,
 }
 
 var (
@@ -505,7 +520,8 @@
 	nil,                            // 5: android.release_config_proto.ReleaseConfigsArtifact.ReleaseConfigMapsMapEntry
 	(*Value)(nil),                  // 6: android.release_config_proto.Value
 	(*FlagDeclaration)(nil),        // 7: android.release_config_proto.FlagDeclaration
-	(*ReleaseConfigMap)(nil),       // 8: android.release_config_proto.ReleaseConfigMap
+	(ReleaseConfigType)(0),         // 8: android.release_config_proto.ReleaseConfigType
+	(*ReleaseConfigMap)(nil),       // 9: android.release_config_proto.ReleaseConfigMap
 }
 var file_build_flags_out_proto_depIdxs = []int32{
 	6,  // 0: android.release_config_proto.Tracepoint.value:type_name -> android.release_config_proto.Value
@@ -514,15 +530,16 @@
 	0,  // 3: android.release_config_proto.FlagArtifact.traces:type_name -> android.release_config_proto.Tracepoint
 	1,  // 4: android.release_config_proto.FlagArtifacts.flags:type_name -> android.release_config_proto.FlagArtifact
 	1,  // 5: android.release_config_proto.ReleaseConfigArtifact.flags:type_name -> android.release_config_proto.FlagArtifact
-	3,  // 6: android.release_config_proto.ReleaseConfigsArtifact.release_config:type_name -> android.release_config_proto.ReleaseConfigArtifact
-	3,  // 7: android.release_config_proto.ReleaseConfigsArtifact.other_release_configs:type_name -> android.release_config_proto.ReleaseConfigArtifact
-	5,  // 8: android.release_config_proto.ReleaseConfigsArtifact.release_config_maps_map:type_name -> android.release_config_proto.ReleaseConfigsArtifact.ReleaseConfigMapsMapEntry
-	8,  // 9: android.release_config_proto.ReleaseConfigsArtifact.ReleaseConfigMapsMapEntry.value:type_name -> android.release_config_proto.ReleaseConfigMap
-	10, // [10:10] is the sub-list for method output_type
-	10, // [10:10] is the sub-list for method input_type
-	10, // [10:10] is the sub-list for extension type_name
-	10, // [10:10] is the sub-list for extension extendee
-	0,  // [0:10] is the sub-list for field type_name
+	8,  // 6: android.release_config_proto.ReleaseConfigArtifact.release_config_type:type_name -> android.release_config_proto.ReleaseConfigType
+	3,  // 7: android.release_config_proto.ReleaseConfigsArtifact.release_config:type_name -> android.release_config_proto.ReleaseConfigArtifact
+	3,  // 8: android.release_config_proto.ReleaseConfigsArtifact.other_release_configs:type_name -> android.release_config_proto.ReleaseConfigArtifact
+	5,  // 9: android.release_config_proto.ReleaseConfigsArtifact.release_config_maps_map:type_name -> android.release_config_proto.ReleaseConfigsArtifact.ReleaseConfigMapsMapEntry
+	9,  // 10: android.release_config_proto.ReleaseConfigsArtifact.ReleaseConfigMapsMapEntry.value:type_name -> android.release_config_proto.ReleaseConfigMap
+	11, // [11:11] is the sub-list for method output_type
+	11, // [11:11] is the sub-list for method input_type
+	11, // [11:11] is the sub-list for extension type_name
+	11, // [11:11] is the sub-list for extension extendee
+	0,  // [0:11] is the sub-list for field type_name
 }
 
 func init() { file_build_flags_out_proto_init() }
diff --git a/cmd/release_config/release_config_proto/build_flags_out.proto b/cmd/release_config/release_config_proto/build_flags_out.proto
index 2ab62d1..55c848e 100644
--- a/cmd/release_config/release_config_proto/build_flags_out.proto
+++ b/cmd/release_config/release_config_proto/build_flags_out.proto
@@ -96,6 +96,9 @@
   // config.  The listed directories contain at least a `release_config` message
   // for this release config.
   repeated string value_directories = 8;
+
+  // The ReleaseConfigType of this release config.
+  optional ReleaseConfigType release_config_type = 9;
 }
 
 message ReleaseConfigsArtifact {
diff --git a/cmd/release_config/release_config_proto/build_flags_src.pb.go b/cmd/release_config/release_config_proto/build_flags_src.pb.go
index 123c6d3..c48c323 100644
--- a/cmd/release_config/release_config_proto/build_flags_src.pb.go
+++ b/cmd/release_config/release_config_proto/build_flags_src.pb.go
@@ -35,6 +35,76 @@
 	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
 )
 
+type ReleaseConfigType int32
+
+const (
+	// This is treated as `RELEASE_CONFIG`.
+	ReleaseConfigType_CONFIG_TYPE_UNSPECIFIED ReleaseConfigType = 0
+	// This is a normal release config.  This is the only ReleaseConfigType with
+	// implicit inheritance.
+	ReleaseConfigType_RELEASE_CONFIG ReleaseConfigType = 1
+	// Same as RELEASE_CONFIG, except no implicit inheritance happens.
+	// This is the "root" release config.
+	ReleaseConfigType_EXPLICIT_INHERITANCE_CONFIG ReleaseConfigType = 2
+	// This is a release config applied based on the TARGET_BUILD_VARIANT
+	// environment variable, if the build flag RELEASE_BUILD_USE_VARIANT_FLAGS is
+	// enabled.
+	ReleaseConfigType_BUILD_VARIANT ReleaseConfigType = 3
+)
+
+// Enum value maps for ReleaseConfigType.
+var (
+	ReleaseConfigType_name = map[int32]string{
+		0: "CONFIG_TYPE_UNSPECIFIED",
+		1: "RELEASE_CONFIG",
+		2: "EXPLICIT_INHERITANCE_CONFIG",
+		3: "BUILD_VARIANT",
+	}
+	ReleaseConfigType_value = map[string]int32{
+		"CONFIG_TYPE_UNSPECIFIED":     0,
+		"RELEASE_CONFIG":              1,
+		"EXPLICIT_INHERITANCE_CONFIG": 2,
+		"BUILD_VARIANT":               3,
+	}
+)
+
+func (x ReleaseConfigType) Enum() *ReleaseConfigType {
+	p := new(ReleaseConfigType)
+	*p = x
+	return p
+}
+
+func (x ReleaseConfigType) String() string {
+	return protoimpl.X.EnumStringOf(x.Descriptor(), protoreflect.EnumNumber(x))
+}
+
+func (ReleaseConfigType) Descriptor() protoreflect.EnumDescriptor {
+	return file_build_flags_src_proto_enumTypes[0].Descriptor()
+}
+
+func (ReleaseConfigType) Type() protoreflect.EnumType {
+	return &file_build_flags_src_proto_enumTypes[0]
+}
+
+func (x ReleaseConfigType) Number() protoreflect.EnumNumber {
+	return protoreflect.EnumNumber(x)
+}
+
+// Deprecated: Do not use.
+func (x *ReleaseConfigType) UnmarshalJSON(b []byte) error {
+	num, err := protoimpl.X.UnmarshalJSONEnum(x.Descriptor(), b)
+	if err != nil {
+		return err
+	}
+	*x = ReleaseConfigType(num)
+	return nil
+}
+
+// Deprecated: Use ReleaseConfigType.Descriptor instead.
+func (ReleaseConfigType) EnumDescriptor() ([]byte, []int) {
+	return file_build_flags_src_proto_rawDescGZIP(), []int{0}
+}
+
 type Value struct {
 	state         protoimpl.MessageState
 	sizeCache     protoimpl.SizeCache
@@ -338,6 +408,8 @@
 	// Prior stage(s) for flag advancement (during development).
 	// Once a flag has met criteria in a prior stage, it can advance to this one.
 	PriorStages []string `protobuf:"bytes,5,rep,name=prior_stages,json=priorStages" json:"prior_stages,omitempty"`
+	// The ReleaseConfigType of this release config.
+	ReleaseConfigType *ReleaseConfigType `protobuf:"varint,6,opt,name=release_config_type,json=releaseConfigType,enum=android.release_config_proto.ReleaseConfigType" json:"release_config_type,omitempty"`
 }
 
 func (x *ReleaseConfig) Reset() {
@@ -407,6 +479,13 @@
 	return nil
 }
 
+func (x *ReleaseConfig) GetReleaseConfigType() ReleaseConfigType {
+	if x != nil && x.ReleaseConfigType != nil {
+		return *x.ReleaseConfigType
+	}
+	return ReleaseConfigType_CONFIG_TYPE_UNSPECIFIED
+}
+
 // Any aliases.  These are used for continuous integration builder config.
 type ReleaseAlias struct {
 	state         protoimpl.MessageState
@@ -576,7 +655,7 @@
 	0x5f, 0x63, 0x6f, 0x6e, 0x66, 0x69, 0x67, 0x5f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x2e, 0x56, 0x61,
 	0x6c, 0x75, 0x65, 0x52, 0x05, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x12, 0x1b, 0x0a, 0x08, 0x72, 0x65,
 	0x64, 0x61, 0x63, 0x74, 0x65, 0x64, 0x18, 0xca, 0x01, 0x20, 0x01, 0x28, 0x08, 0x52, 0x08, 0x72,
-	0x65, 0x64, 0x61, 0x63, 0x74, 0x65, 0x64, 0x22, 0xbe, 0x01, 0x0a, 0x0d, 0x52, 0x65, 0x6c, 0x65,
+	0x65, 0x64, 0x61, 0x63, 0x74, 0x65, 0x64, 0x22, 0x9f, 0x02, 0x0a, 0x0d, 0x52, 0x65, 0x6c, 0x65,
 	0x61, 0x73, 0x65, 0x43, 0x6f, 0x6e, 0x66, 0x69, 0x67, 0x12, 0x12, 0x0a, 0x04, 0x6e, 0x61, 0x6d,
 	0x65, 0x18, 0x01, 0x20, 0x01, 0x28, 0x09, 0x52, 0x04, 0x6e, 0x61, 0x6d, 0x65, 0x12, 0x1a, 0x0a,
 	0x08, 0x69, 0x6e, 0x68, 0x65, 0x72, 0x69, 0x74, 0x73, 0x18, 0x02, 0x20, 0x03, 0x28, 0x09, 0x52,
@@ -588,25 +667,38 @@
 	0x01, 0x28, 0x08, 0x52, 0x10, 0x61, 0x63, 0x6f, 0x6e, 0x66, 0x69, 0x67, 0x46, 0x6c, 0x61, 0x67,
 	0x73, 0x4f, 0x6e, 0x6c, 0x79, 0x12, 0x21, 0x0a, 0x0c, 0x70, 0x72, 0x69, 0x6f, 0x72, 0x5f, 0x73,
 	0x74, 0x61, 0x67, 0x65, 0x73, 0x18, 0x05, 0x20, 0x03, 0x28, 0x09, 0x52, 0x0b, 0x70, 0x72, 0x69,
-	0x6f, 0x72, 0x53, 0x74, 0x61, 0x67, 0x65, 0x73, 0x22, 0x3a, 0x0a, 0x0c, 0x52, 0x65, 0x6c, 0x65,
-	0x61, 0x73, 0x65, 0x41, 0x6c, 0x69, 0x61, 0x73, 0x12, 0x12, 0x0a, 0x04, 0x6e, 0x61, 0x6d, 0x65,
-	0x18, 0x01, 0x20, 0x01, 0x28, 0x09, 0x52, 0x04, 0x6e, 0x61, 0x6d, 0x65, 0x12, 0x16, 0x0a, 0x06,
-	0x74, 0x61, 0x72, 0x67, 0x65, 0x74, 0x18, 0x02, 0x20, 0x01, 0x28, 0x09, 0x52, 0x06, 0x74, 0x61,
-	0x72, 0x67, 0x65, 0x74, 0x22, 0xa9, 0x01, 0x0a, 0x10, 0x52, 0x65, 0x6c, 0x65, 0x61, 0x73, 0x65,
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+	0x44, 0x10, 0x00, 0x12, 0x12, 0x0a, 0x0e, 0x52, 0x45, 0x4c, 0x45, 0x41, 0x53, 0x45, 0x5f, 0x43,
+	0x4f, 0x4e, 0x46, 0x49, 0x47, 0x10, 0x01, 0x12, 0x1f, 0x0a, 0x1b, 0x45, 0x58, 0x50, 0x4c, 0x49,
+	0x43, 0x49, 0x54, 0x5f, 0x49, 0x4e, 0x48, 0x45, 0x52, 0x49, 0x54, 0x41, 0x4e, 0x43, 0x45, 0x5f,
+	0x43, 0x4f, 0x4e, 0x46, 0x49, 0x47, 0x10, 0x02, 0x12, 0x11, 0x0a, 0x0d, 0x42, 0x55, 0x49, 0x4c,
+	0x44, 0x5f, 0x56, 0x41, 0x52, 0x49, 0x41, 0x4e, 0x54, 0x10, 0x03, 0x42, 0x33, 0x5a, 0x31, 0x61,
+	0x6e, 0x64, 0x72, 0x6f, 0x69, 0x64, 0x2f, 0x73, 0x6f, 0x6f, 0x6e, 0x67, 0x2f, 0x72, 0x65, 0x6c,
+	0x65, 0x61, 0x73, 0x65, 0x5f, 0x63, 0x6f, 0x6e, 0x66, 0x69, 0x67, 0x2f, 0x72, 0x65, 0x6c, 0x65,
+	0x61, 0x73, 0x65, 0x5f, 0x63, 0x6f, 0x6e, 0x66, 0x69, 0x67, 0x5f, 0x70, 0x72, 0x6f, 0x74, 0x6f,
 }
 
 var (
@@ -621,26 +713,29 @@
 	return file_build_flags_src_proto_rawDescData
 }
 
+var file_build_flags_src_proto_enumTypes = make([]protoimpl.EnumInfo, 1)
 var file_build_flags_src_proto_msgTypes = make([]protoimpl.MessageInfo, 6)
 var file_build_flags_src_proto_goTypes = []interface{}{
-	(*Value)(nil),            // 0: android.release_config_proto.Value
-	(*FlagDeclaration)(nil),  // 1: android.release_config_proto.FlagDeclaration
-	(*FlagValue)(nil),        // 2: android.release_config_proto.FlagValue
-	(*ReleaseConfig)(nil),    // 3: android.release_config_proto.ReleaseConfig
-	(*ReleaseAlias)(nil),     // 4: android.release_config_proto.ReleaseAlias
-	(*ReleaseConfigMap)(nil), // 5: android.release_config_proto.ReleaseConfigMap
-	(Workflow)(0),            // 6: android.release_config_proto.Workflow
+	(ReleaseConfigType)(0),   // 0: android.release_config_proto.ReleaseConfigType
+	(*Value)(nil),            // 1: android.release_config_proto.Value
+	(*FlagDeclaration)(nil),  // 2: android.release_config_proto.FlagDeclaration
+	(*FlagValue)(nil),        // 3: android.release_config_proto.FlagValue
+	(*ReleaseConfig)(nil),    // 4: android.release_config_proto.ReleaseConfig
+	(*ReleaseAlias)(nil),     // 5: android.release_config_proto.ReleaseAlias
+	(*ReleaseConfigMap)(nil), // 6: android.release_config_proto.ReleaseConfigMap
+	(Workflow)(0),            // 7: android.release_config_proto.Workflow
 }
 var file_build_flags_src_proto_depIdxs = []int32{
-	0, // 0: android.release_config_proto.FlagDeclaration.value:type_name -> android.release_config_proto.Value
-	6, // 1: android.release_config_proto.FlagDeclaration.workflow:type_name -> android.release_config_proto.Workflow
-	0, // 2: android.release_config_proto.FlagValue.value:type_name -> android.release_config_proto.Value
-	4, // 3: android.release_config_proto.ReleaseConfigMap.aliases:type_name -> android.release_config_proto.ReleaseAlias
-	4, // [4:4] is the sub-list for method output_type
-	4, // [4:4] is the sub-list for method input_type
-	4, // [4:4] is the sub-list for extension type_name
-	4, // [4:4] is the sub-list for extension extendee
-	0, // [0:4] is the sub-list for field type_name
+	1, // 0: android.release_config_proto.FlagDeclaration.value:type_name -> android.release_config_proto.Value
+	7, // 1: android.release_config_proto.FlagDeclaration.workflow:type_name -> android.release_config_proto.Workflow
+	1, // 2: android.release_config_proto.FlagValue.value:type_name -> android.release_config_proto.Value
+	0, // 3: android.release_config_proto.ReleaseConfig.release_config_type:type_name -> android.release_config_proto.ReleaseConfigType
+	5, // 4: android.release_config_proto.ReleaseConfigMap.aliases:type_name -> android.release_config_proto.ReleaseAlias
+	5, // [5:5] is the sub-list for method output_type
+	5, // [5:5] is the sub-list for method input_type
+	5, // [5:5] is the sub-list for extension type_name
+	5, // [5:5] is the sub-list for extension extendee
+	0, // [0:5] is the sub-list for field type_name
 }
 
 func init() { file_build_flags_src_proto_init() }
@@ -734,13 +829,14 @@
 		File: protoimpl.DescBuilder{
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_build_flags_src_proto_rawDesc,
-			NumEnums:      0,
+			NumEnums:      1,
 			NumMessages:   6,
 			NumExtensions: 0,
 			NumServices:   0,
 		},
 		GoTypes:           file_build_flags_src_proto_goTypes,
 		DependencyIndexes: file_build_flags_src_proto_depIdxs,
+		EnumInfos:         file_build_flags_src_proto_enumTypes,
 		MessageInfos:      file_build_flags_src_proto_msgTypes,
 	}.Build()
 	File_build_flags_src_proto = out.File
diff --git a/cmd/release_config/release_config_proto/build_flags_src.proto b/cmd/release_config/release_config_proto/build_flags_src.proto
index b28b5e2..e42ac31 100644
--- a/cmd/release_config/release_config_proto/build_flags_src.proto
+++ b/cmd/release_config/release_config_proto/build_flags_src.proto
@@ -98,6 +98,24 @@
   optional bool redacted = 202;
 }
 
+enum ReleaseConfigType {
+  // This is treated as `RELEASE_CONFIG`.
+  CONFIG_TYPE_UNSPECIFIED = 0;
+
+  // This is a normal release config.  This is the only ReleaseConfigType with
+  // implicit inheritance.
+  RELEASE_CONFIG = 1;
+
+  // Same as RELEASE_CONFIG, except no implicit inheritance happens.
+  // This is the "root" release config.
+  EXPLICIT_INHERITANCE_CONFIG = 2;
+
+  // This is a release config applied based on the TARGET_BUILD_VARIANT
+  // environment variable, if the build flag RELEASE_BUILD_USE_VARIANT_FLAGS is
+  // enabled.
+  BUILD_VARIANT = 3;
+}
+
 // This replaces $(call declare-release-config).
 message ReleaseConfig {
   // The name of the release config.
@@ -117,6 +135,9 @@
   // Prior stage(s) for flag advancement (during development).
   // Once a flag has met criteria in a prior stage, it can advance to this one.
   repeated string prior_stages = 5;
+
+  // The ReleaseConfigType of this release config.
+  optional ReleaseConfigType release_config_type = 6;
 }
 
 // Any aliases.  These are used for continuous integration builder config.
diff --git a/cmd/release_config/release_config_proto/regen.sh b/cmd/release_config/release_config_proto/regen.sh
old mode 100644
new mode 100755