Build a static library for header-only libraries

library.static() was being used to determine if a library was static,
shared, or header only, which resulted in header only libraries
behaving like shared libraries, when they should be treated as static
libraries with no sources.  Explicitly use library.static(),
library.shared(), and library.header() instead.

Bug: 35228396
Test: builds, manually examine changes to build.ninja and Android.mk
Change-Id: I51729992cc6338deda1396b86f12bc9f73e674d8

cc/library.go

@@ -64,7 +64,9 @@ type LibraryProperties struct {
 		// export headers generated from .proto sources
 		Export_proto_headers bool
 	}
+}
 
+type LibraryMutatedProperties struct {
 	VariantName string `blueprint:"mutated"`
 
 	// Build a static variant
@@ -175,7 +177,8 @@ var _ exportedFlagsProducer = (*flagExporter)(nil)
 // libraryDecorator wraps baseCompiler, baseLinker and baseInstaller to provide library-specific
 // functionality: static vs. shared linkage, reusing object files for shared libraries
 type libraryDecorator struct {
-	Properties LibraryProperties
+	Properties        LibraryProperties
+	MutatedProperties LibraryMutatedProperties
 
 	// For reusing static library objects for shared library
 	reuseObjects Objects
@@ -213,6 +216,7 @@ func (library *libraryDecorator) linkerProps() []interface{} {
 	props = append(props, library.baseLinker.linkerProps()...)
 	return append(props,
 		&library.Properties,
+		&library.MutatedProperties,
 		&library.flagExporter.Properties,
 		&library.stripper.StripProperties,
 		&library.relocationPacker.Properties)
@@ -230,11 +234,11 @@ func (library *libraryDecorator) linkerFlags(ctx ModuleContext, flags Flags) Fla
 
 	if library.static() {
 		flags.CFlags = append(flags.CFlags, library.Properties.Static.Cflags...)
-	} else {
+	} else if library.shared() {
 		flags.CFlags = append(flags.CFlags, library.Properties.Shared.Cflags...)
 	}
 
-	if !library.static() {
+	if library.shared() {
 		libName := library.getLibName(ctx)
 		// GCC for Android assumes that -shared means -Bsymbolic, use -Wl,-shared instead
 		sharedFlag := "-Wl,-shared"
@@ -303,7 +307,7 @@ func (library *libraryDecorator) compile(ctx ModuleContext, flags Flags, deps Pa
 		srcs := android.PathsForModuleSrc(ctx, library.Properties.Static.Srcs)
 		objs = objs.Append(compileObjs(ctx, buildFlags, android.DeviceStaticLibrary,
 			srcs, library.baseCompiler.deps))
-	} else {
+	} else if library.shared() {
 		srcs := android.PathsForModuleSrc(ctx, library.Properties.Shared.Srcs)
 		objs = objs.Append(compileObjs(ctx, buildFlags, android.DeviceSharedLibrary,
 			srcs, library.baseCompiler.deps))
@@ -324,7 +328,8 @@ type libraryInterface interface {
 	buildShared() bool
 
 	// Sets whether a specific variant is static or shared
-	setStatic(bool)
+	setStatic()
+	setShared()
 }
 
 func (library *libraryDecorator) getLibName(ctx ModuleContext) string {
@@ -339,7 +344,7 @@ func (library *libraryDecorator) getLibName(ctx ModuleContext) string {
 		}
 	}
 
-	return name + library.Properties.VariantName
+	return name + library.MutatedProperties.VariantName
 }
 
 func (library *libraryDecorator) linkerInit(ctx BaseModuleContext) {
@@ -362,7 +367,7 @@ func (library *libraryDecorator) linkerDeps(ctx DepsContext, deps Deps) Deps {
 			library.Properties.Static.Whole_static_libs...)
 		deps.StaticLibs = append(deps.StaticLibs, library.Properties.Static.Static_libs...)
 		deps.SharedLibs = append(deps.SharedLibs, library.Properties.Static.Shared_libs...)
-	} else {
+	} else if library.shared() {
 		if ctx.toolchain().Bionic() && !Bool(library.baseLinker.Properties.Nocrt) {
 			if !ctx.sdk() && !ctx.vndk() {
 				deps.CrtBegin = "crtbegin_so"
@@ -395,13 +400,13 @@ func (library *libraryDecorator) linkStatic(ctx ModuleContext,
 	library.objects = library.objects.Append(objs)
 
 	outputFile := android.PathForModuleOut(ctx,
-		ctx.ModuleName()+library.Properties.VariantName+staticLibraryExtension)
+		ctx.ModuleName()+library.MutatedProperties.VariantName+staticLibraryExtension)
 	builderFlags := flagsToBuilderFlags(flags)
 
 	TransformObjToStaticLib(ctx, library.objects.objFiles, builderFlags, outputFile, objs.tidyFiles)
 
 	library.coverageOutputFile = TransformCoverageFilesToLib(ctx, library.objects, builderFlags,
-		ctx.ModuleName()+library.Properties.VariantName)
+		ctx.ModuleName()+library.MutatedProperties.VariantName)
 
 	library.wholeStaticMissingDeps = ctx.GetMissingDependencies()
 
@@ -522,7 +527,7 @@ func (library *libraryDecorator) link(ctx ModuleContext,
 	objs = objs.Append(deps.Objs)
 
 	var out android.Path
-	if library.static() {
+	if library.static() || library.header() {
 		out = library.linkStatic(ctx, flags, deps, objs)
 	} else {
 		out = library.linkShared(ctx, flags, deps, objs)
@@ -555,12 +560,12 @@ func (library *libraryDecorator) link(ctx ModuleContext,
 }
 
 func (library *libraryDecorator) buildStatic() bool {
-	return library.Properties.BuildStatic &&
+	return library.MutatedProperties.BuildStatic &&
 		(library.Properties.Static.Enabled == nil || *library.Properties.Static.Enabled)
 }
 
 func (library *libraryDecorator) buildShared() bool {
-	return library.Properties.BuildShared &&
+	return library.MutatedProperties.BuildShared &&
 		(library.Properties.Shared.Enabled == nil || *library.Properties.Shared.Enabled)
 }
 
@@ -587,31 +592,45 @@ func (library *libraryDecorator) install(ctx ModuleContext, file android.Path) {
 }
 
 func (library *libraryDecorator) static() bool {
-	return library.Properties.VariantIsStatic
+	return library.MutatedProperties.VariantIsStatic
 }
 
-func (library *libraryDecorator) setStatic(static bool) {
+func (library *libraryDecorator) shared() bool {
-	library.Properties.VariantIsStatic = static
+	return library.MutatedProperties.VariantIsShared
+}
+
+func (library *libraryDecorator) header() bool {
+	return !library.static() && !library.shared()
+}
+
+func (library *libraryDecorator) setStatic() {
+	library.MutatedProperties.VariantIsStatic = true
+	library.MutatedProperties.VariantIsShared = false
+}
+
+func (library *libraryDecorator) setShared() {
+	library.MutatedProperties.VariantIsStatic = false
+	library.MutatedProperties.VariantIsShared = true
 }
 
 func (library *libraryDecorator) BuildOnlyStatic() {
-	library.Properties.BuildShared = false
+	library.MutatedProperties.BuildShared = false
 }
 
 func (library *libraryDecorator) BuildOnlyShared() {
-	library.Properties.BuildStatic = false
+	library.MutatedProperties.BuildStatic = false
 }
 
 func (library *libraryDecorator) HeaderOnly() {
-	library.Properties.BuildShared = false
+	library.MutatedProperties.BuildShared = false
-	library.Properties.BuildStatic = false
+	library.MutatedProperties.BuildStatic = false
 }
 
 func NewLibrary(hod android.HostOrDeviceSupported) (*Module, *libraryDecorator) {
 	module := newModule(hod, android.MultilibBoth)
 
 	library := &libraryDecorator{
-		Properties: LibraryProperties{
+		MutatedProperties: LibraryMutatedProperties{
 			BuildShared: true,
 			BuildStatic: true,
 		},
@@ -637,8 +656,8 @@ func linkageMutator(mctx android.BottomUpMutatorContext) {
 				static := modules[0].(*Module)
 				shared := modules[1].(*Module)
 
-				static.linker.(libraryInterface).setStatic(true)
+				static.linker.(libraryInterface).setStatic()
-				shared.linker.(libraryInterface).setStatic(false)
+				shared.linker.(libraryInterface).setShared()
 
 				if staticCompiler, ok := static.compiler.(*libraryDecorator); ok {
 					sharedCompiler := shared.compiler.(*libraryDecorator)
@@ -652,10 +671,10 @@ func linkageMutator(mctx android.BottomUpMutatorContext) {
 				}
 			} else if library.buildStatic() {
 				modules = mctx.CreateLocalVariations("static")
-				modules[0].(*Module).linker.(libraryInterface).setStatic(true)
+				modules[0].(*Module).linker.(libraryInterface).setStatic()
 			} else if library.buildShared() {
 				modules = mctx.CreateLocalVariations("shared")
-				modules[0].(*Module).linker.(libraryInterface).setStatic(false)
+				modules[0].(*Module).linker.(libraryInterface).setShared()
 			}
 		}
 	}

cc/ndk_library.go

@@ -335,7 +335,7 @@ func newStubLibrary() (*Module, []interface{}) {
 	module.linker = stub
 	module.installer = stub
 
-	return module, []interface{}{&stub.properties}
+	return module, []interface{}{&stub.properties, &library.MutatedProperties}
 }
 
 func ndkLibraryFactory() (blueprint.Module, []interface{}) {

cc/ndk_prebuilt.go

@@ -194,7 +194,7 @@ func (ndk *ndkPrebuiltStlLinker) link(ctx ModuleContext, flags Flags,
 
 	libName := strings.TrimPrefix(ctx.ModuleName(), "ndk_")
 	libExt := flags.Toolchain.ShlibSuffix()
-	if ndk.Properties.BuildStatic {
+	if ndk.static() {
 		libExt = staticLibraryExtension
 	}