Merge changes from topic "cc_prebuilt_stubs" into main

* changes:
  Skip `-Wl,--version-script` on libclang_rt.* stubs (temp hack)
  Special case the stubgen args for bionic libs
  Add stub generation support to cc_prebuilt_library

apex/apex_test.go

@@ -906,7 +906,7 @@ func TestApexWithStubs(t *testing.T) {
 		cc_library {
 			name: "mylib",
 			srcs: ["mylib.cpp"],
-			shared_libs: ["mylib2", "mylib3"],
+			shared_libs: ["mylib2", "mylib3", "my_prebuilt_platform_lib", "my_prebuilt_platform_stub_only_lib"],
 			system_shared_libs: [],
 			stl: "none",
 			apex_available: [ "myapex" ],
@@ -919,6 +919,7 @@ func TestApexWithStubs(t *testing.T) {
 			system_shared_libs: [],
 			stl: "none",
 			stubs: {
+				symbol_file: "mylib2.map.txt",
 				versions: ["1", "2", "3"],
 			},
 		}
@@ -930,6 +931,7 @@ func TestApexWithStubs(t *testing.T) {
 			system_shared_libs: [],
 			stl: "none",
 			stubs: {
+				symbol_file: "mylib3.map.txt",
 				versions: ["10", "11", "12"],
 			},
 			apex_available: [ "myapex" ],
@@ -943,6 +945,24 @@ func TestApexWithStubs(t *testing.T) {
 			apex_available: [ "myapex" ],
 		}
 
+		cc_prebuilt_library_shared {
+			name: "my_prebuilt_platform_lib",
+			stubs: {
+				symbol_file: "my_prebuilt_platform_lib.map.txt",
+				versions: ["1", "2", "3"],
+			},
+			srcs: ["foo.so"],
+		}
+
+		// Similar to my_prebuilt_platform_lib, but this library only provides stubs, i.e. srcs is empty
+		cc_prebuilt_library_shared {
+			name: "my_prebuilt_platform_stub_only_lib",
+			stubs: {
+				symbol_file: "my_prebuilt_platform_stub_only_lib.map.txt",
+				versions: ["1", "2", "3"],
+			}
+		}
+
 		rust_binary {
 			name: "foo.rust",
 			srcs: ["foo.rs"],
@@ -1022,6 +1042,20 @@ func TestApexWithStubs(t *testing.T) {
 
 	apexManifestRule := ctx.ModuleForTests("myapex", "android_common_myapex").Rule("apexManifestRule")
 	ensureListContains(t, names(apexManifestRule.Args["requireNativeLibs"]), "libfoo.shared_from_rust.so")
+
+	// Ensure that mylib is linking with the latest version of stubs for my_prebuilt_platform_lib
+	ensureContains(t, mylibLdFlags, "my_prebuilt_platform_lib/android_arm64_armv8-a_shared_current/my_prebuilt_platform_lib.so")
+	// ... and not linking to the non-stub (impl) variant of my_prebuilt_platform_lib
+	ensureNotContains(t, mylibLdFlags, "my_prebuilt_platform_lib/android_arm64_armv8-a_shared/my_prebuilt_platform_lib.so")
+	// Ensure that genstub for platform-provided lib is invoked with --systemapi
+	ensureContains(t, ctx.ModuleForTests("my_prebuilt_platform_lib", "android_arm64_armv8-a_shared_3").Rule("genStubSrc").Args["flags"], "--systemapi")
+
+	// Ensure that mylib is linking with the latest version of stubs for my_prebuilt_platform_lib
+	ensureContains(t, mylibLdFlags, "my_prebuilt_platform_stub_only_lib/android_arm64_armv8-a_shared_current/my_prebuilt_platform_stub_only_lib.so")
+	// ... and not linking to the non-stub (impl) variant of my_prebuilt_platform_lib
+	ensureNotContains(t, mylibLdFlags, "my_prebuilt_platform_stub_only_lib/android_arm64_armv8-a_shared/my_prebuilt_platform_stub_only_lib.so")
+	// Ensure that genstub for platform-provided lib is invoked with --systemapi
+	ensureContains(t, ctx.ModuleForTests("my_prebuilt_platform_stub_only_lib", "android_arm64_armv8-a_shared_3").Rule("genStubSrc").Args["flags"], "--systemapi")
 }
 
 func TestApexShouldNotEmbedStubVariant(t *testing.T) {
@@ -1156,6 +1190,7 @@ func TestApexWithStubsWithMinSdkVersion(t *testing.T) {
 			system_shared_libs: [],
 			stl: "none",
 			stubs: {
+				symbol_file: "mylib2.map.txt",
 				versions: ["28", "29", "30", "current"],
 			},
 			min_sdk_version: "28",
@@ -1168,6 +1203,7 @@ func TestApexWithStubsWithMinSdkVersion(t *testing.T) {
 			system_shared_libs: [],
 			stl: "none",
 			stubs: {
+				symbol_file: "mylib3.map.txt",
 				versions: ["28", "29", "30", "current"],
 			},
 			apex_available: [ "myapex" ],
@@ -11940,7 +11976,7 @@ func TestPrebuiltStubNoinstall(t *testing.T) {
 		).RunTest(t)
 
 		ldRule := result.ModuleForTests("installedlib", "android_arm64_armv8-a_shared").Rule("ld")
-		android.AssertStringDoesContain(t, "", ldRule.Args["libFlags"], "android_arm64_armv8-a_shared/libfoo.so")
+		android.AssertStringDoesContain(t, "", ldRule.Args["libFlags"], "android_arm64_armv8-a_shared_current/libfoo.so")
 
 		installRules := result.InstallMakeRulesForTesting(t)
 

cc/cc_test.go

@@ -927,7 +927,7 @@ func TestLlndkLibrary(t *testing.T) {
 
 	cc_prebuilt_library_shared {
 		name: "libllndkprebuilt",
-		stubs: { versions: ["1", "2"] },
+		stubs: { versions: ["1", "2"] , symbol_file: "libllndkprebuilt.map.txt" },
 		llndk: {
 			symbol_file: "libllndkprebuilt.map.txt",
 		},

cc/library.go

@@ -594,43 +594,7 @@ func (library *libraryDecorator) compile(ctx ModuleContext, flags Flags, deps Pa
 		return objs
 	}
 	if library.buildStubs() {
-		symbolFile := String(library.Properties.Stubs.Symbol_file)
+		return library.compileModuleLibApiStubs(ctx, flags, deps)
-		if symbolFile != "" && !strings.HasSuffix(symbolFile, ".map.txt") {
-			ctx.PropertyErrorf("symbol_file", "%q doesn't have .map.txt suffix", symbolFile)
-			return Objects{}
-		}
-		library.stubsSymbolFilePath = android.PathForModuleSrc(ctx, symbolFile)
-		// b/239274367 --apex and --systemapi filters symbols tagged with # apex and #
-		// systemapi, respectively. The former is for symbols defined in platform libraries
-		// and the latter is for symbols defined in APEXes.
-		// A single library can contain either # apex or # systemapi, but not both.
-		// The stub generator (ndkstubgen) is additive, so passing _both_ of these to it should be a no-op.
-		// However, having this distinction helps guard accidental
-		// promotion or demotion of API and also helps the API review process b/191371676
-		var flag string
-		if ctx.Module().(android.ApexModule).NotInPlatform() {
-			flag = "--apex"
-		} else {
-			flag = "--systemapi"
-		}
-		// b/184712170, unless the lib is an NDK library, exclude all public symbols from
-		// the stub so that it is mandated that all symbols are explicitly marked with
-		// either apex or systemapi.
-		if !ctx.Module().(*Module).IsNdk(ctx.Config()) {
-			flag = flag + " --no-ndk"
-		}
-		nativeAbiResult := parseNativeAbiDefinition(ctx, symbolFile,
-			android.ApiLevelOrPanic(ctx, library.MutatedProperties.StubsVersion), flag)
-		objs := compileStubLibrary(ctx, flags, nativeAbiResult.stubSrc)
-		library.versionScriptPath = android.OptionalPathForPath(
-			nativeAbiResult.versionScript)
-
-		// Parse symbol file to get API list for coverage
-		if library.stubsVersion() == "current" && ctx.PrimaryArch() && !ctx.inRecovery() && !ctx.inProduct() && !ctx.inVendor() {
-			library.apiListCoverageXmlPath = parseSymbolFileForAPICoverage(ctx, symbolFile)
-		}
-
-		return objs
 	}
 
 	srcs := library.baseCompiler.Properties.Srcs.GetOrDefault(ctx, nil)
@@ -681,6 +645,61 @@ func (library *libraryDecorator) compile(ctx ModuleContext, flags Flags, deps Pa
 	return objs
 }
 
+// Compile stubs for the API surface between platform and apex
+// This method will be used by source and prebuilt cc module types.
+func (library *libraryDecorator) compileModuleLibApiStubs(ctx ModuleContext, flags Flags, deps PathDeps) Objects {
+	// TODO (b/275273834): Make this a hard error when the symbol files have been added to module sdk.
+	if library.Properties.Stubs.Symbol_file == nil {
+		return Objects{}
+	}
+	symbolFile := String(library.Properties.Stubs.Symbol_file)
+	library.stubsSymbolFilePath = android.PathForModuleSrc(ctx, symbolFile)
+	// b/239274367 --apex and --systemapi filters symbols tagged with # apex and #
+	// systemapi, respectively. The former is for symbols defined in platform libraries
+	// and the latter is for symbols defined in APEXes.
+	// A single library can contain either # apex or # systemapi, but not both.
+	// The stub generator (ndkstubgen) is additive, so passing _both_ of these to it should be a no-op.
+	// However, having this distinction helps guard accidental
+	// promotion or demotion of API and also helps the API review process b/191371676
+	var flag string
+	if ctx.Module().(android.ApexModule).NotInPlatform() {
+		flag = "--apex"
+	} else {
+		flag = "--systemapi"
+	}
+	// b/184712170, unless the lib is an NDK library, exclude all public symbols from
+	// the stub so that it is mandated that all symbols are explicitly marked with
+	// either apex or systemapi.
+	if !ctx.Module().(*Module).IsNdk(ctx.Config()) &&
+		// the symbol files of libclang libs are autogenerated and do not contain systemapi tags
+		// TODO (spandandas): Update mapfile.py to include #systemapi tag on all symbols
+		!strings.Contains(ctx.ModuleName(), "libclang_rt") {
+		flag = flag + " --no-ndk"
+	}
+	// TODO(b/361303067): Remove this special case if bionic/ projects are added to ART development branches.
+	if isBionic(ctx.baseModuleName()) {
+		// set the flags explicitly for bionic libs.
+		// this is necessary for development in minimal branches which does not contain bionic/*.
+		// In such minimal branches, e.g. on the prebuilt libc stubs
+		// 1. IsNdk will return false (since the ndk_library definition for libc does not exist)
+		// 2. NotInPlatform will return true (since the source com.android.runtime does not exist)
+		flag = "--apex"
+	}
+	nativeAbiResult := parseNativeAbiDefinition(ctx, symbolFile,
+		android.ApiLevelOrPanic(ctx, library.MutatedProperties.StubsVersion), flag)
+	objs := compileStubLibrary(ctx, flags, nativeAbiResult.stubSrc)
+
+	library.versionScriptPath = android.OptionalPathForPath(
+		nativeAbiResult.versionScript)
+
+	// Parse symbol file to get API list for coverage
+	if library.stubsVersion() == "current" && ctx.PrimaryArch() && !ctx.inRecovery() && !ctx.inProduct() && !ctx.inVendor() {
+		library.apiListCoverageXmlPath = parseSymbolFileForAPICoverage(ctx, symbolFile)
+	}
+
+	return objs
+}
+
 type libraryInterface interface {
 	versionedInterface
 
@@ -1182,12 +1201,17 @@ func (library *libraryDecorator) linkShared(ctx ModuleContext,
 	return unstrippedOutputFile
 }
 
-func addStubDependencyProviders(ctx ModuleContext) {
+// Visits the stub variants of the library and returns a struct containing the stub .so paths
+func addStubDependencyProviders(ctx ModuleContext) []SharedStubLibrary {
+	stubsInfo := []SharedStubLibrary{}
 	stubs := ctx.GetDirectDepsWithTag(stubImplDepTag)
 	if len(stubs) > 0 {
-		var stubsInfo []SharedStubLibrary
 		for _, stub := range stubs {
-			stubInfo, _ := android.OtherModuleProvider(ctx, stub, SharedLibraryInfoProvider)
+			stubInfo, ok := android.OtherModuleProvider(ctx, stub, SharedLibraryInfoProvider)
+			// TODO (b/275273834): Make this a hard error when the symbol files have been added to module sdk.
+			if !ok {
+				continue
+			}
 			flagInfo, _ := android.OtherModuleProvider(ctx, stub, FlagExporterInfoProvider)
 			stubsInfo = append(stubsInfo, SharedStubLibrary{
 				Version:           moduleLibraryInterface(stub).stubsVersion(),
@@ -1195,12 +1219,15 @@ func addStubDependencyProviders(ctx ModuleContext) {
 				FlagExporterInfo:  flagInfo,
 			})
 		}
+		if len(stubsInfo) > 0 {
 			android.SetProvider(ctx, SharedLibraryStubsProvider, SharedLibraryStubsInfo{
 				SharedStubLibraries: stubsInfo,
 				IsLLNDK:             ctx.IsLlndk(),
 			})
 		}
 	}
+	return stubsInfo
+}
 
 func (library *libraryDecorator) unstrippedOutputFilePath() android.Path {
 	return library.unstrippedOutputFile

cc/prebuilt.go

@@ -16,6 +16,7 @@ package cc
 
 import (
 	"path/filepath"
+	"strings"
 
 	"github.com/google/blueprint/proptools"
 
@@ -95,10 +96,6 @@ func (p *prebuiltLibraryLinker) linkerDeps(ctx DepsContext, deps Deps) Deps {
 	return p.libraryDecorator.linkerDeps(ctx, deps)
 }
 
-func (p *prebuiltLibraryLinker) linkerFlags(ctx ModuleContext, flags Flags) Flags {
-	return flags
-}
-
 func (p *prebuiltLibraryLinker) linkerProps() []interface{} {
 	return p.libraryDecorator.linkerProps()
 }
@@ -117,6 +114,30 @@ func (p *prebuiltLibraryLinker) link(ctx ModuleContext,
 
 	// TODO(ccross): verify shared library dependencies
 	srcs := p.prebuiltSrcs(ctx)
+	stubInfo := addStubDependencyProviders(ctx)
+
+	// Stub variants will create a stub .so file from stub .c files
+	if p.buildStubs() && objs.objFiles != nil {
+		// TODO (b/275273834): Make objs.objFiles == nil a hard error when the symbol files have been added to module sdk.
+
+		// The map.txt files of libclang_rt.* contain version information, but the checked in .so files do not.
+		// e.g. libclang_rt.* libs impl
+		// $ nm -D prebuilts/../libclang_rt.hwasan-aarch64-android.so
+		// __hwasan_init
+
+		// stubs generated from .map.txt
+		// $ nm -D out/soong/.intermediates/../<stubs>/libclang_rt.hwasan-aarch64-android.so
+		// __hwasan_init@@LIBCLANG_RT_ASAN
+
+		// Special-case libclang_rt.* libs to account for this discrepancy.
+		// TODO (spandandas): Remove this special case https://r.android.com/3236596 has been submitted, and a new set of map.txt
+		// files of libclang_rt.* libs have been generated.
+		if strings.Contains(ctx.ModuleName(), "libclang_rt.") {
+			p.versionScriptPath = android.OptionalPathForPath(nil)
+		}
+		return p.linkShared(ctx, flags, deps, objs)
+	}
+
 	if len(srcs) > 0 {
 		if len(srcs) > 1 {
 			ctx.PropertyErrorf("srcs", "multiple prebuilt source files")
@@ -203,6 +224,16 @@ func (p *prebuiltLibraryLinker) link(ctx ModuleContext,
 
 			return outputFile
 		}
+	} else if p.shared() && len(stubInfo) > 0 {
+		// This is a prebuilt which does not have any implementation (nil `srcs`), but provides APIs.
+		// Provide the latest (i.e. `current`) stubs to reverse dependencies.
+		latestStub := stubInfo[len(stubInfo)-1].SharedLibraryInfo.SharedLibrary
+		android.SetProvider(ctx, SharedLibraryInfoProvider, SharedLibraryInfo{
+			SharedLibrary: latestStub,
+			Target:        ctx.Target(),
+		})
+
+		return latestStub
 	}
 
 	if p.header() {
@@ -257,11 +288,11 @@ func (p *prebuiltLibraryLinker) implementationModuleName(name string) string {
 
 func NewPrebuiltLibrary(hod android.HostOrDeviceSupported, srcsProperty string) (*Module, *libraryDecorator) {
 	module, library := NewLibrary(hod)
-	module.compiler = nil
 
 	prebuilt := &prebuiltLibraryLinker{
 		libraryDecorator: library,
 	}
+	module.compiler = prebuilt
 	module.linker = prebuilt
 	module.library = prebuilt
 
@@ -280,6 +311,13 @@ func NewPrebuiltLibrary(hod android.HostOrDeviceSupported, srcsProperty string)
 	return module, library
 }
 
+func (p *prebuiltLibraryLinker) compile(ctx ModuleContext, flags Flags, deps PathDeps) Objects {
+	if p.buildStubs() && p.stubsVersion() != "" {
+		return p.compileModuleLibApiStubs(ctx, flags, deps)
+	}
+	return Objects{}
+}
+
 // cc_prebuilt_library installs a precompiled shared library that are
 // listed in the srcs property in the device's directory.
 func PrebuiltLibraryFactory() android.Module {