Fix prebuilt selection logic for cc_prebuilt_library_headers.

Unlike other prebuilt modules it doesn't have a srcs property of any
kind, so android.Prebuilt cannot defer to the source module just
because its srcsSupplier would return nil.

Test: m nothing
Bug: 202192894
Change-Id: Iafcf165569bad6eae37820cf71aa0fcacb720e02

android/prebuilt.go

@@ -97,7 +97,10 @@ type ConfigVarProperties struct {
 type Prebuilt struct {
 	properties PrebuiltProperties
 
+	// nil if the prebuilt has no srcs property at all. See InitPrebuiltModuleWithoutSrcs.
 	srcsSupplier PrebuiltSrcsSupplier
+
+	// "-" if the prebuilt has no srcs property at all. See InitPrebuiltModuleWithoutSrcs.
 	srcsPropertyName string
 }
 
@@ -177,6 +180,23 @@ func (p *Prebuilt) UsePrebuilt() bool {
 // Return the src value or nil if it is not available.
 type PrebuiltSrcsSupplier func(ctx BaseModuleContext, prebuilt Module) []string
 
+func initPrebuiltModuleCommon(module PrebuiltInterface) *Prebuilt {
+	p := module.Prebuilt()
+	module.AddProperties(&p.properties)
+	module.base().customizableProperties = module.GetProperties()
+	return p
+}
+
+// Initialize the module as a prebuilt module that has no dedicated property that lists its
+// sources. SingleSourcePathFromSupplier should not be called for this module.
+//
+// This is the case e.g. for header modules, which provides the headers in source form
+// regardless whether they are prebuilt or not.
+func InitPrebuiltModuleWithoutSrcs(module PrebuiltInterface) {
+	p := initPrebuiltModuleCommon(module)
+	p.srcsPropertyName = "-"
+}
+
 // Initialize the module as a prebuilt module that uses the provided supplier to access the
 // prebuilt sources of the module.
 //
@@ -190,10 +210,6 @@ type PrebuiltSrcsSupplier func(ctx BaseModuleContext, prebuilt Module) []string
 // The provided property name is used to provide helpful error messages in the event that
 // a problem arises, e.g. calling SingleSourcePath() when more than one source is provided.
 func InitPrebuiltModuleWithSrcSupplier(module PrebuiltInterface, srcsSupplier PrebuiltSrcsSupplier, srcsPropertyName string) {
-	p := module.Prebuilt()
-	module.AddProperties(&p.properties)
-	module.base().customizableProperties = module.GetProperties()
-
 	if srcsSupplier == nil {
 		panic(fmt.Errorf("srcsSupplier must not be nil"))
 	}
@@ -201,6 +217,7 @@ func InitPrebuiltModuleWithSrcSupplier(module PrebuiltInterface, srcsSupplier Pr
 		panic(fmt.Errorf("srcsPropertyName must not be empty"))
 	}
 
+	p := initPrebuiltModuleCommon(module)
 	p.srcsSupplier = srcsSupplier
 	p.srcsPropertyName = srcsPropertyName
 }
@@ -336,7 +353,7 @@ func PrebuiltSourceDepsMutator(ctx BottomUpMutatorContext) {
 func PrebuiltSelectModuleMutator(ctx TopDownMutatorContext) {
 	m := ctx.Module()
 	if p := GetEmbeddedPrebuilt(m); p != nil {
-		if p.srcsSupplier == nil {
+		if p.srcsSupplier == nil && p.srcsPropertyName == "" {
 			panic(fmt.Errorf("prebuilt module did not have InitPrebuiltModule called on it"))
 		}
 		if !p.properties.SourceExists {

cc/androidmk.go

@@ -263,9 +263,10 @@ func (library *libraryDecorator) AndroidMkEntries(ctx AndroidMkContext, entries
 		library.androidMkWriteExportedFlags(entries)
 		library.androidMkEntriesWriteAdditionalDependenciesForSourceAbiDiff(entries)
 
+		if entries.OutputFile.Valid() {
 			_, _, ext := android.SplitFileExt(entries.OutputFile.Path().Base())
-
 			entries.SetString("LOCAL_BUILT_MODULE_STEM", "$(LOCAL_MODULE)"+ext)
+		}
 
 		if library.coverageOutputFile.Valid() {
 			entries.SetString("LOCAL_PREBUILT_COVERAGE_ARCHIVE", library.coverageOutputFile.String())

cc/library_headers.go

@@ -102,7 +102,7 @@ func LibraryHeaderFactory() android.Module {
 
 // cc_prebuilt_library_headers is a prebuilt version of cc_library_headers
 func prebuiltLibraryHeaderFactory() android.Module {
-	module, library := NewPrebuiltLibrary(android.HostAndDeviceSupported)
+	module, library := NewPrebuiltLibrary(android.HostAndDeviceSupported, "")
 	library.HeaderOnly()
 	return module.Init()
 }

cc/library_headers_test.go

@@ -15,8 +15,13 @@
 package cc
 
 import (
+	"fmt"
 	"strings"
 	"testing"
+
+	"android/soong/android"
+
+	"github.com/google/blueprint"
 )
 
 func TestLibraryHeaders(t *testing.T) {
@@ -60,3 +65,43 @@ func TestPrebuiltLibraryHeaders(t *testing.T) {
 		t.Errorf("cflags for libsystem must contain -Imy_include, but was %#v.", cflags)
 	}
 }
+
+func TestPrebuiltLibraryHeadersPreferred(t *testing.T) {
+	bp := `
+		cc_library_headers {
+			name: "headers",
+			export_include_dirs: ["my_include"],
+		}
+		cc_prebuilt_library_headers {
+			name: "headers",
+			prefer: %t,
+			export_include_dirs: ["my_include"],
+		}
+		cc_library_static {
+			name: "lib",
+			srcs: ["foo.c"],
+			header_libs: ["headers"],
+		}
+	`
+
+	for _, prebuiltPreferred := range []bool{false, true} {
+		t.Run(fmt.Sprintf("prebuilt prefer %t", prebuiltPreferred), func(t *testing.T) {
+			ctx := testCc(t, fmt.Sprintf(bp, prebuiltPreferred))
+			lib := ctx.ModuleForTests("lib", "android_arm64_armv8-a_static")
+			sourceDep := ctx.ModuleForTests("headers", "android_arm64_armv8-a")
+			prebuiltDep := ctx.ModuleForTests("prebuilt_headers", "android_arm64_armv8-a")
+			hasSourceDep := false
+			hasPrebuiltDep := false
+			ctx.VisitDirectDeps(lib.Module(), func(dep blueprint.Module) {
+				if dep == sourceDep.Module() {
+					hasSourceDep = true
+				}
+				if dep == prebuiltDep.Module() {
+					hasPrebuiltDep = true
+				}
+			})
+			android.AssertBoolEquals(t, "depends on source headers", !prebuiltPreferred, hasSourceDep)
+			android.AssertBoolEquals(t, "depends on prebuilt headers", prebuiltPreferred, hasPrebuiltDep)
+		})
+	}
+}

cc/prebuilt.go

@@ -235,7 +235,7 @@ func (p *prebuiltLibraryLinker) implementationModuleName(name string) string {
 	return android.RemoveOptionalPrebuiltPrefix(name)
 }
 
-func NewPrebuiltLibrary(hod android.HostOrDeviceSupported) (*Module, *libraryDecorator) {
+func NewPrebuiltLibrary(hod android.HostOrDeviceSupported, srcsProperty string) (*Module, *libraryDecorator) {
 	module, library := NewLibrary(hod)
 	module.compiler = nil
 
@@ -247,11 +247,15 @@ func NewPrebuiltLibrary(hod android.HostOrDeviceSupported) (*Module, *libraryDec
 
 	module.AddProperties(&prebuilt.properties)
 
+	if srcsProperty == "" {
+		android.InitPrebuiltModuleWithoutSrcs(module)
+	} else {
 		srcsSupplier := func(ctx android.BaseModuleContext, _ android.Module) []string {
 			return prebuilt.prebuiltSrcs(ctx)
 		}
 
-	android.InitPrebuiltModuleWithSrcSupplier(module, srcsSupplier, "srcs")
+		android.InitPrebuiltModuleWithSrcSupplier(module, srcsSupplier, srcsProperty)
+	}
 
 	// Prebuilt libraries can be used in SDKs.
 	android.InitSdkAwareModule(module)
@@ -261,7 +265,7 @@ func NewPrebuiltLibrary(hod android.HostOrDeviceSupported) (*Module, *libraryDec
 // cc_prebuilt_library installs a precompiled shared library that are
 // listed in the srcs property in the device's directory.
 func PrebuiltLibraryFactory() android.Module {
-	module, _ := NewPrebuiltLibrary(android.HostAndDeviceSupported)
+	module, _ := NewPrebuiltLibrary(android.HostAndDeviceSupported, "srcs")
 
 	// Prebuilt shared libraries can be included in APEXes
 	android.InitApexModule(module)
@@ -280,14 +284,14 @@ func PrebuiltSharedLibraryFactory() android.Module {
 // to be used as a data dependency of a test-related module (such as cc_test, or
 // cc_test_library).
 func PrebuiltSharedTestLibraryFactory() android.Module {
-	module, library := NewPrebuiltLibrary(android.HostAndDeviceSupported)
+	module, library := NewPrebuiltLibrary(android.HostAndDeviceSupported, "srcs")
 	library.BuildOnlyShared()
 	library.baseInstaller = NewTestInstaller()
 	return module.Init()
 }
 
 func NewPrebuiltSharedLibrary(hod android.HostOrDeviceSupported) (*Module, *libraryDecorator) {
-	module, library := NewPrebuiltLibrary(hod)
+	module, library := NewPrebuiltLibrary(hod, "srcs")
 	library.BuildOnlyShared()
 
 	// Prebuilt shared libraries can be included in APEXes
@@ -304,7 +308,7 @@ func PrebuiltStaticLibraryFactory() android.Module {
 }
 
 func NewPrebuiltStaticLibrary(hod android.HostOrDeviceSupported) (*Module, *libraryDecorator) {
-	module, library := NewPrebuiltLibrary(hod)
+	module, library := NewPrebuiltLibrary(hod, "srcs")
 	library.BuildOnlyStatic()
 	module.bazelHandler = &prebuiltStaticLibraryBazelHandler{module: module, library: library}
 	return module, library