Generate "exportable" stubs library in java_sdk_library

Given that now the droidstubs module generates the "exportable" stubs,
this change modifies java_sdk_library to generate the java_library
modules that compiles the "exportable" stubs per api scope.
The detailed naming scheme of the generated modules are available in the
bug linked in the footer.

Similar to the from-text java_api_library vs from-source java_library
static lib selection for the "everything" stubs, the "exportable" stubs
module can also toggle between the stubs java_api_library and the
java_library module. However, given that the "exportable" stubs
generation has not been implemented for from-text stubs, the module
always default to depend on the from-source "exportable" stubs compiling
java_library module.

Test: go test ./java
Bug: 315495926
Change-Id: I5798312c1338c55625b2030da728b056385171a4
diff --git a/java/droidstubs.go b/java/droidstubs.go
index 5fbf6c0..bdbaf92 100644
--- a/java/droidstubs.go
+++ b/java/droidstubs.go
@@ -1329,7 +1329,9 @@
 
 func (p *PrebuiltStubsSources) OutputFiles(tag string) (android.Paths, error) {
 	switch tag {
-	case "":
+	// prebuilt droidstubs does not output "exportable" stubs.
+	// Output the "everything" stubs srcjar file if the tag is ".exportable".
+	case "", ".exportable":
 		return android.Paths{p.stubsSrcJar}, nil
 	default:
 		return nil, fmt.Errorf("unsupported module reference tag %q", tag)
diff --git a/java/sdk_library.go b/java/sdk_library.go
index 6998bd2..0df869e 100644
--- a/java/sdk_library.go
+++ b/java/sdk_library.go
@@ -231,6 +231,10 @@
 	return ".stubs" + scope.moduleSuffix
 }
 
+func (scope *apiScope) exportableStubsLibraryModuleNameSuffix() string {
+	return ".stubs.exportable" + scope.moduleSuffix
+}
+
 func (scope *apiScope) apiLibraryModuleName(baseName string) string {
 	return scope.stubsLibraryModuleName(baseName) + ".from-text"
 }
@@ -239,10 +243,18 @@
 	return scope.stubsLibraryModuleName(baseName) + ".from-source"
 }
 
+func (scope *apiScope) exportableSourceStubsLibraryModuleName(baseName string) string {
+	return scope.exportableStubsLibraryModuleName(baseName) + ".from-source"
+}
+
 func (scope *apiScope) stubsLibraryModuleName(baseName string) string {
 	return baseName + scope.stubsLibraryModuleNameSuffix()
 }
 
+func (scope *apiScope) exportableStubsLibraryModuleName(baseName string) string {
+	return baseName + scope.exportableStubsLibraryModuleNameSuffix()
+}
+
 func (scope *apiScope) stubsSourceModuleName(baseName string) string {
 	return baseName + ".stubs.source" + scope.moduleSuffix
 }
@@ -895,6 +907,12 @@
 	return c.namingScheme.stubsLibraryModuleName(apiScope, baseName)
 }
 
+// Name of the java_library module that compiles the exportable stubs source.
+func (c *commonToSdkLibraryAndImport) exportableStubsLibraryModuleName(apiScope *apiScope) string {
+	baseName := c.module.BaseModuleName()
+	return c.namingScheme.exportableStubsLibraryModuleName(apiScope, baseName)
+}
+
 // Name of the droidstubs module that generates the stubs source and may also
 // generate/check the API.
 func (c *commonToSdkLibraryAndImport) stubsSourceModuleName(apiScope *apiScope) string {
@@ -911,9 +929,16 @@
 
 // Name of the java_library module that compiles the stubs
 // generated from source Java files.
-func (c *commonToSdkLibraryAndImport) sourceStubLibraryModuleName(apiScope *apiScope) string {
+func (c *commonToSdkLibraryAndImport) sourceStubsLibraryModuleName(apiScope *apiScope) string {
 	baseName := c.module.BaseModuleName()
-	return c.namingScheme.sourceStubLibraryModuleName(apiScope, baseName)
+	return c.namingScheme.sourceStubsLibraryModuleName(apiScope, baseName)
+}
+
+// Name of the java_library module that compiles the exportable stubs
+// generated from source Java files.
+func (c *commonToSdkLibraryAndImport) exportableSourceStubsLibraryModuleName(apiScope *apiScope) string {
+	baseName := c.module.BaseModuleName()
+	return c.namingScheme.exportableSourceStubsLibraryModuleName(apiScope, baseName)
 }
 
 // The component names for different outputs of the java_sdk_library.
@@ -1629,36 +1654,34 @@
 	mctx.CreateModule(LibraryFactory, properties...)
 }
 
-// Creates a static java library that has API stubs
-func (module *SdkLibrary) createStubsLibrary(mctx android.DefaultableHookContext, apiScope *apiScope) {
-	props := struct {
-		Name           *string
-		Visibility     []string
-		Srcs           []string
-		Installable    *bool
-		Sdk_version    *string
-		System_modules *string
-		Patch_module   *string
-		Libs           []string
-		Static_libs    []string
-		Compile_dex    *bool
-		Java_version   *string
-		Openjdk9       struct {
-			Srcs       []string
-			Javacflags []string
-		}
-		Dist struct {
-			Targets []string
-			Dest    *string
-			Dir     *string
-			Tag     *string
-		}
-	}{}
+type libraryProperties struct {
+	Name           *string
+	Visibility     []string
+	Srcs           []string
+	Installable    *bool
+	Sdk_version    *string
+	System_modules *string
+	Patch_module   *string
+	Libs           []string
+	Static_libs    []string
+	Compile_dex    *bool
+	Java_version   *string
+	Openjdk9       struct {
+		Srcs       []string
+		Javacflags []string
+	}
+	Dist struct {
+		Targets []string
+		Dest    *string
+		Dir     *string
+		Tag     *string
+	}
+}
 
-	props.Name = proptools.StringPtr(module.sourceStubLibraryModuleName(apiScope))
+func (module *SdkLibrary) stubsLibraryProps(mctx android.DefaultableHookContext, apiScope *apiScope) libraryProperties {
+	props := libraryProperties{}
 	props.Visibility = []string{"//visibility:override", "//visibility:private"}
 	// sources are generated from the droiddoc
-	props.Srcs = []string{":" + module.stubsSourceModuleName(apiScope)}
 	sdkVersion := module.sdkVersionForStubsLibrary(mctx, apiScope)
 	props.Sdk_version = proptools.StringPtr(sdkVersion)
 	props.System_modules = module.deviceProperties.System_modules
@@ -1678,6 +1701,25 @@
 	// interop with older developer tools that don't support 1.9.
 	props.Java_version = proptools.StringPtr("1.8")
 
+	return props
+}
+
+// Creates a static java library that has API stubs
+func (module *SdkLibrary) createStubsLibrary(mctx android.DefaultableHookContext, apiScope *apiScope) {
+
+	props := module.stubsLibraryProps(mctx, apiScope)
+	props.Name = proptools.StringPtr(module.sourceStubsLibraryModuleName(apiScope))
+	props.Srcs = []string{":" + module.stubsSourceModuleName(apiScope)}
+
+	mctx.CreateModule(LibraryFactory, &props, module.sdkComponentPropertiesForChildLibrary())
+}
+
+// Create a static java library that compiles the "exportable" stubs
+func (module *SdkLibrary) createExportableStubsLibrary(mctx android.DefaultableHookContext, apiScope *apiScope) {
+	props := module.stubsLibraryProps(mctx, apiScope)
+	props.Name = proptools.StringPtr(module.exportableSourceStubsLibraryModuleName(apiScope))
+	props.Srcs = []string{":" + module.stubsSourceModuleName(apiScope) + "{.exportable}"}
+
 	mctx.CreateModule(LibraryFactory, &props, module.sdkComponentPropertiesForChildLibrary())
 }
 
@@ -1908,43 +1950,15 @@
 	mctx.CreateModule(ApiLibraryFactory, &props, module.sdkComponentPropertiesForChildLibrary())
 }
 
-func (module *SdkLibrary) createTopLevelStubsLibrary(
-	mctx android.DefaultableHookContext, apiScope *apiScope, contributesToApiSurface bool) {
-	props := struct {
-		Name           *string
-		Visibility     []string
-		Sdk_version    *string
-		Static_libs    []string
-		System_modules *string
-		Dist           struct {
-			Targets []string
-			Dest    *string
-			Dir     *string
-			Tag     *string
-		}
-		Compile_dex *bool
-	}{}
-	props.Name = proptools.StringPtr(module.stubsLibraryModuleName(apiScope))
+func (module *SdkLibrary) topLevelStubsLibraryProps(mctx android.DefaultableHookContext, apiScope *apiScope) libraryProperties {
+	props := libraryProperties{}
+
 	props.Visibility = childModuleVisibility(module.sdkLibraryProperties.Stubs_library_visibility)
 	sdkVersion := module.sdkVersionForStubsLibrary(mctx, apiScope)
 	props.Sdk_version = proptools.StringPtr(sdkVersion)
 
-	// Add the stub compiling java_library/java_api_library as static lib based on build config
-	staticLib := module.sourceStubLibraryModuleName(apiScope)
-	if mctx.Config().BuildFromTextStub() && contributesToApiSurface {
-		staticLib = module.apiLibraryModuleName(apiScope)
-	}
-	props.Static_libs = append(props.Static_libs, staticLib)
 	props.System_modules = module.deviceProperties.System_modules
 
-	// Dist the class jar artifact for sdk builds.
-	if !Bool(module.sdkLibraryProperties.No_dist) {
-		props.Dist.Targets = []string{"sdk", "win_sdk"}
-		props.Dist.Dest = proptools.StringPtr(fmt.Sprintf("%v.jar", module.distStem()))
-		props.Dist.Dir = proptools.StringPtr(module.apiDistPath(apiScope))
-		props.Dist.Tag = proptools.StringPtr(".jar")
-	}
-
 	// The imports need to be compiled to dex if the java_sdk_library requests it.
 	compileDex := module.dexProperties.Compile_dex
 	if module.stubLibrariesCompiledForDex() {
@@ -1952,6 +1966,43 @@
 	}
 	props.Compile_dex = compileDex
 
+	return props
+}
+
+func (module *SdkLibrary) createTopLevelStubsLibrary(
+	mctx android.DefaultableHookContext, apiScope *apiScope, contributesToApiSurface bool) {
+
+	props := module.topLevelStubsLibraryProps(mctx, apiScope)
+	props.Name = proptools.StringPtr(module.stubsLibraryModuleName(apiScope))
+
+	// Add the stub compiling java_library/java_api_library as static lib based on build config
+	staticLib := module.sourceStubsLibraryModuleName(apiScope)
+	if mctx.Config().BuildFromTextStub() && contributesToApiSurface {
+		staticLib = module.apiLibraryModuleName(apiScope)
+	}
+	props.Static_libs = append(props.Static_libs, staticLib)
+
+	mctx.CreateModule(LibraryFactory, &props, module.sdkComponentPropertiesForChildLibrary())
+}
+
+func (module *SdkLibrary) createTopLevelExportableStubsLibrary(
+	mctx android.DefaultableHookContext, apiScope *apiScope) {
+
+	props := module.topLevelStubsLibraryProps(mctx, apiScope)
+	props.Name = proptools.StringPtr(module.exportableStubsLibraryModuleName(apiScope))
+
+	// Dist the class jar artifact for sdk builds.
+	// "exportable" stubs are copied to dist for sdk builds instead of the "everything" stubs.
+	if !Bool(module.sdkLibraryProperties.No_dist) {
+		props.Dist.Targets = []string{"sdk", "win_sdk"}
+		props.Dist.Dest = proptools.StringPtr(fmt.Sprintf("%v.jar", module.distStem()))
+		props.Dist.Dir = proptools.StringPtr(module.apiDistPath(apiScope))
+		props.Dist.Tag = proptools.StringPtr(".jar")
+	}
+
+	staticLib := module.exportableSourceStubsLibraryModuleName(apiScope)
+	props.Static_libs = append(props.Static_libs, staticLib)
+
 	mctx.CreateModule(LibraryFactory, &props, module.sdkComponentPropertiesForChildLibrary())
 }
 
@@ -2157,6 +2208,7 @@
 		module.createStubsSourcesAndApi(mctx, scope, module.stubsSourceModuleName(scope), scope.droidstubsArgs)
 
 		module.createStubsLibrary(mctx, scope)
+		module.createExportableStubsLibrary(mctx, scope)
 
 		alternativeFullApiSurfaceStubLib := ""
 		if scope == apiScopePublic {
@@ -2168,6 +2220,7 @@
 		}
 
 		module.createTopLevelStubsLibrary(mctx, scope, contributesToApiSurface)
+		module.createTopLevelExportableStubsLibrary(mctx, scope)
 	}
 
 	if module.requiresRuntimeImplementationLibrary() {
@@ -2223,7 +2276,11 @@
 
 	apiLibraryModuleName(scope *apiScope, baseName string) string
 
-	sourceStubLibraryModuleName(scope *apiScope, baseName string) string
+	sourceStubsLibraryModuleName(scope *apiScope, baseName string) string
+
+	exportableStubsLibraryModuleName(scope *apiScope, baseName string) string
+
+	exportableSourceStubsLibraryModuleName(scope *apiScope, baseName string) string
 }
 
 type defaultNamingScheme struct {
@@ -2241,34 +2298,47 @@
 	return scope.apiLibraryModuleName(baseName)
 }
 
-func (s *defaultNamingScheme) sourceStubLibraryModuleName(scope *apiScope, baseName string) string {
+func (s *defaultNamingScheme) sourceStubsLibraryModuleName(scope *apiScope, baseName string) string {
 	return scope.sourceStubLibraryModuleName(baseName)
 }
 
+func (s *defaultNamingScheme) exportableStubsLibraryModuleName(scope *apiScope, baseName string) string {
+	return scope.exportableStubsLibraryModuleName(baseName)
+}
+
+func (s *defaultNamingScheme) exportableSourceStubsLibraryModuleName(scope *apiScope, baseName string) string {
+	return scope.exportableSourceStubsLibraryModuleName(baseName)
+}
+
 var _ sdkLibraryComponentNamingScheme = (*defaultNamingScheme)(nil)
 
+func hasStubsLibrarySuffix(name string, apiScope *apiScope) bool {
+	return strings.HasSuffix(name, apiScope.stubsLibraryModuleNameSuffix()) ||
+		strings.HasSuffix(name, apiScope.exportableStubsLibraryModuleNameSuffix())
+}
+
 func moduleStubLinkType(name string) (stub bool, ret sdkLinkType) {
 	name = strings.TrimSuffix(name, ".from-source")
 
 	// This suffix-based approach is fragile and could potentially mis-trigger.
 	// TODO(b/155164730): Clean this up when modules no longer reference sdk_lib stubs directly.
-	if strings.HasSuffix(name, apiScopePublic.stubsLibraryModuleNameSuffix()) {
+	if hasStubsLibrarySuffix(name, apiScopePublic) {
 		if name == "hwbinder.stubs" || name == "libcore_private.stubs" {
 			// Due to a previous bug, these modules were not considered stubs, so we retain that.
 			return false, javaPlatform
 		}
 		return true, javaSdk
 	}
-	if strings.HasSuffix(name, apiScopeSystem.stubsLibraryModuleNameSuffix()) {
+	if hasStubsLibrarySuffix(name, apiScopeSystem) {
 		return true, javaSystem
 	}
-	if strings.HasSuffix(name, apiScopeModuleLib.stubsLibraryModuleNameSuffix()) {
+	if hasStubsLibrarySuffix(name, apiScopeModuleLib) {
 		return true, javaModule
 	}
-	if strings.HasSuffix(name, apiScopeTest.stubsLibraryModuleNameSuffix()) {
+	if hasStubsLibrarySuffix(name, apiScopeTest) {
 		return true, javaSystem
 	}
-	if strings.HasSuffix(name, apiScopeSystemServer.stubsLibraryModuleNameSuffix()) {
+	if hasStubsLibrarySuffix(name, apiScopeSystemServer) {
 		return true, javaSystemServer
 	}
 	return false, javaPlatform
diff --git a/java/sdk_library_test.go b/java/sdk_library_test.go
index 63419d6..c14f3e6 100644
--- a/java/sdk_library_test.go
+++ b/java/sdk_library_test.go
@@ -1423,7 +1423,7 @@
 
 	for _, tt := range testCases {
 		t.Run(tt.module, func(t *testing.T) {
-			m := result.ModuleForTests(tt.module+".stubs", "android_common").Module().(*Library)
+			m := result.ModuleForTests(apiScopePublic.exportableStubsLibraryModuleName(tt.module), "android_common").Module().(*Library)
 			dists := m.Dists()
 			if len(dists) != 1 {
 				t.Fatalf("expected exactly 1 dist entry, got %d", len(dists))
@@ -1693,3 +1693,56 @@
 
 	android.AssertStringDoesContain(t, "bar.xml java_sdk_xml command", barPermissions.RuleParams.Command, `dependency=\"foo\"`)
 }
+
+func TestSdkLibraryExportableStubsLibrary(t *testing.T) {
+	result := android.GroupFixturePreparers(
+		prepareForJavaTest,
+		PrepareForTestWithJavaSdkLibraryFiles,
+		FixtureWithLastReleaseApis("foo"),
+		android.FixtureModifyConfig(func(config android.Config) {
+			config.SetApiLibraries([]string{"foo"})
+		}),
+	).RunTestWithBp(t, `
+		aconfig_declarations {
+			name: "bar",
+			package: "com.example.package",
+			srcs: [
+				"bar.aconfig",
+			],
+		}
+		java_sdk_library {
+			name: "foo",
+			srcs: ["a.java", "b.java"],
+			api_packages: ["foo"],
+			system: {
+				enabled: true,
+			},
+			module_lib: {
+				enabled: true,
+			},
+			test: {
+				enabled: true,
+			},
+			aconfig_declarations: [
+				"bar",
+			],
+		}
+	`)
+
+	exportableStubsLibraryModuleName := apiScopePublic.exportableStubsLibraryModuleName("foo")
+	exportableSourceStubsLibraryModuleName := apiScopePublic.exportableSourceStubsLibraryModuleName("foo")
+
+	// Check modules generation
+	topLevelModule := result.ModuleForTests(exportableStubsLibraryModuleName, "android_common")
+	result.ModuleForTests(exportableSourceStubsLibraryModuleName, "android_common")
+
+	// Check static lib dependency
+	android.AssertBoolEquals(t, "exportable top level stubs library module depends on the"+
+		"exportable source stubs library module", true,
+		CheckModuleHasDependency(t, result.TestContext, exportableStubsLibraryModuleName,
+			"android_common", exportableSourceStubsLibraryModuleName),
+	)
+	android.AssertArrayString(t, "exportable source stub library is a static lib of the"+
+		"top level exportable stubs library", []string{exportableSourceStubsLibraryModuleName},
+		topLevelModule.Module().(*Library).properties.Static_libs)
+}