Add aconfig_declarations property to droidstubs and java_sdk_library

In consideration of the incremental build performance, this change let
droidstubs and java_sdk_library (which generates droidstubs per api
scope) modules to specify `aconfig_declaration` modules where the
dependent flags are defined in via the "aconfig_declarations" property,
opposed to passing uniform "all_aconfig_declaration"-generated flag
arguments to metalava.

When "aconfig_declarations" property is defined for java_sdk_library
modules, the property is passed to the generated droidstubs modules.

When "aconfig_declarations" property is defined for droidstubs modules,
the all aconfig_declaration modules listed in the property are listed as
deps, all cache protobuf files are gathered and metalava-consumable
flags are generated in "revert-annotations.txt".

Although this change introduces scalable implementation to easily
support generation of the "runtime" stubs corresponding flags, actual
support of the runtime flags/stubs will be done in future changes. This
change mostly focuses on the generation of the "exportable" flags.

Utilization of the generated "exportable" flags will be done in future
changes.

Test: go test ./java
Bug: 315485740
Change-Id: I37becd1b9dd9069d7ac4abed130906df30b3fdf4

java/droidstubs.go

@@ -30,6 +30,27 @@ import (
 // The values allowed for Droidstubs' Api_levels_sdk_type
 var allowedApiLevelSdkTypes = []string{"public", "system", "module-lib", "system-server"}
 
+type StubsType int
+
+const (
+	Everything StubsType = iota
+	Runtime
+	Exportable
+)
+
+func (s StubsType) String() string {
+	switch s {
+	case Everything:
+		return "everything"
+	case Runtime:
+		return "runtime"
+	case Exportable:
+		return "exportable"
+	default:
+		return ""
+	}
+}
+
 func init() {
 	RegisterStubsBuildComponents(android.InitRegistrationContext)
 }
@@ -151,6 +172,10 @@ type DroidstubsProperties struct {
 	// API surface of this module. If set, the module contributes to an API surface.
 	// For the full list of available API surfaces, refer to soong/android/sdk_version.go
 	Api_surface *string
+
+	// a list of aconfig_declarations module names that the stubs generated in this module
+	// depend on.
+	Aconfig_declarations []string
 }
 
 // Used by xsd_config
@@ -274,6 +299,12 @@ func (d *Droidstubs) DepsMutator(ctx android.BottomUpMutatorContext) {
 		}
 	}
 
+	if len(d.properties.Aconfig_declarations) != 0 {
+		for _, aconfigDeclarationModuleName := range d.properties.Aconfig_declarations {
+			ctx.AddDependency(ctx.Module(), aconfigDeclarationTag, aconfigDeclarationModuleName)
+		}
+	}
+
 	if d.properties.Api_levels_module != nil {
 		ctx.AddDependency(ctx.Module(), metalavaAPILevelsModuleTag, proptools.String(d.properties.Api_levels_module))
 	}
@@ -538,11 +569,59 @@ func metalavaCmd(ctx android.ModuleContext, rule *android.RuleBuilder, javaVersi
 	return cmd
 }
 
+// Generate flagged apis related flags. Apply transformations and only revert the flagged apis
+// that are not enabled via release configurations and are not specified in aconfig_declarations
+func (d *Droidstubs) generateRevertAnnotationArgs(ctx android.ModuleContext, stubsType StubsType, aconfigFlagsPaths android.Paths) {
+
+	releasedFlaggedApisFile := android.PathForModuleOut(ctx, fmt.Sprintf("released-flagged-apis-%s.txt", stubsType.String()))
+	revertAnnotationsFile := android.PathForModuleOut(ctx, fmt.Sprintf("revert-annotations-%s.txt", stubsType.String()))
+
+	var filterArgs string
+	switch stubsType {
+	// No flagged apis specific flags need to be passed to metalava when generating
+	// everything stubs
+	case Everything:
+		return
+
+	case Runtime:
+		filterArgs = "--filter='state:ENABLED+permission:READ_ONLY' --filter='permission:READ_WRITE'"
+
+	case Exportable:
+		filterArgs = "--filter='state:ENABLED+permission:READ_ONLY'"
+
+	}
+
+	ctx.Build(pctx, android.BuildParams{
+		Rule:        gatherReleasedFlaggedApisRule,
+		Inputs:      aconfigFlagsPaths,
+		Output:      releasedFlaggedApisFile,
+		Description: fmt.Sprintf("%s gather aconfig flags", stubsType),
+		Args: map[string]string{
+			"flags_path":  android.JoinPathsWithPrefix(aconfigFlagsPaths, "--cache "),
+			"filter_args": filterArgs,
+		},
+	})
+
+	ctx.Build(pctx, android.BuildParams{
+		Rule:        generateMetalavaRevertAnnotationsRule,
+		Input:       releasedFlaggedApisFile,
+		Output:      revertAnnotationsFile,
+		Description: fmt.Sprintf("%s revert annotations", stubsType),
+	})
+}
+
 func (d *Droidstubs) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 	deps := d.Javadoc.collectDeps(ctx)
 
 	javaVersion := getJavaVersion(ctx, String(d.Javadoc.properties.Java_version), android.SdkContext(d))
 
+	// If the module specifies aconfig_declarations property, "exportable" (and "runtime" eventually) stubs are generated
+	if len(deps.aconfigProtoFiles) > 0 {
+		// Files required to generate "exportable" stubs
+		stubsType := Exportable
+		d.generateRevertAnnotationArgs(ctx, stubsType, deps.aconfigProtoFiles)
+	}
+
 	// Create rule for metalava
 
 	srcJarDir := android.PathForModuleOut(ctx, "metalava", "srcjars")