Make override modules compatible with prebuilts.

Prebuilt's prefer flag doesn't work against override modules because
override modules are sort of virtual modules that delegate all the work
to their base modules. Therefore, even if a prebuilt module suppresses
installation of its src-counterpart override module, the actual build
actions are still performed in the base module.

This change fixes it by filtering out override modules that are being
replaced by prebuilts.

Test: prebuilt_test.go
Bug: 152155285
Change-Id: I859b35c0629b2b6258dd1ec5e020ba2c77ff9612

android/override_module.go

@@ -208,7 +208,21 @@ var overrideBaseDepTag overrideBaseDependencyTag
 // next phase.
 func overrideModuleDepsMutator(ctx BottomUpMutatorContext) {
 	if module, ok := ctx.Module().(OverrideModule); ok {
-		ctx.AddDependency(ctx.Module(), overrideBaseDepTag, *module.getOverrideModuleProperties().Base)
+		// Skip this overriding module if there's a prebuilt module that overrides it with prefer flag.
+		overriddenByPrebuilt := false
+		ctx.VisitDirectDepsWithTag(PrebuiltDepTag, func(dep Module) {
+			prebuilt, ok := dep.(PrebuiltInterface)
+			if !ok {
+				panic("PrebuiltDepTag leads to a non-prebuilt module " + dep.Name())
+			}
+			if prebuilt.Prebuilt().UsePrebuilt() {
+				overriddenByPrebuilt = true
+				return
+			}
+		})
+		if !overriddenByPrebuilt {
+			ctx.AddDependency(ctx.Module(), overrideBaseDepTag, *module.getOverrideModuleProperties().Base)
+		}
 	}
 }
 

android/prebuilt_test.go

@@ -155,6 +155,44 @@ var prebuiltsTests = []struct {
 			}`,
 		prebuilt: []OsClass{Host},
 	},
+	{
+		name: "prebuilt override not preferred",
+		modules: `
+			source {
+				name: "baz",
+			}
+
+			override_source {
+				name: "bar",
+				base: "baz",
+			}
+
+			prebuilt {
+				name: "bar",
+				prefer: false,
+				srcs: ["prebuilt_file"],
+			}`,
+		prebuilt: nil,
+	},
+	{
+		name: "prebuilt override preferred",
+		modules: `
+			source {
+				name: "baz",
+			}
+
+			override_source {
+				name: "bar",
+				base: "baz",
+			}
+
+			prebuilt {
+				name: "bar",
+				prefer: true,
+				srcs: ["prebuilt_file"],
+			}`,
+		prebuilt: []OsClass{Device, Host},
+	},
 }
 
 func TestPrebuilts(t *testing.T) {
@@ -256,8 +294,10 @@ func TestPrebuilts(t *testing.T) {
 func registerTestPrebuiltBuildComponents(ctx RegistrationContext) {
 	ctx.RegisterModuleType("prebuilt", newPrebuiltModule)
 	ctx.RegisterModuleType("source", newSourceModule)
+	ctx.RegisterModuleType("override_source", newOverrideSourceModule)
 
 	RegisterPrebuiltMutators(ctx)
+	ctx.PostDepsMutators(RegisterOverridePostDepsMutators)
 }
 
 type prebuiltModule struct {
@@ -300,11 +340,15 @@ func (p *prebuiltModule) OutputFiles(tag string) (Paths, error) {
 	}
 }
 
+type sourceModuleProperties struct {
+	Deps []string `android:"path,arch_variant"`
+}
+
 type sourceModule struct {
 	ModuleBase
-	properties struct {
-		Deps []string `android:"path,arch_variant"`
-	}
+	OverridableModuleBase
+
+	properties                                     sourceModuleProperties
 	dependsOnSourceModule, dependsOnPrebuiltModule bool
 	deps                                           Paths
 	src                                            Path
@@ -314,10 +358,11 @@ func newSourceModule() Module {
 	m := &sourceModule{}
 	m.AddProperties(&m.properties)
 	InitAndroidArchModule(m, HostAndDeviceDefault, MultilibCommon)
+	InitOverridableModule(m, nil)
 	return m
 }
 
-func (s *sourceModule) DepsMutator(ctx BottomUpMutatorContext) {
+func (s *sourceModule) OverridablePropertiesDepsMutator(ctx BottomUpMutatorContext) {
 	// s.properties.Deps are annotated with android:path, so they are
 	// automatically added to the dependency by pathDeps mutator
 }
@@ -330,3 +375,20 @@ func (s *sourceModule) GenerateAndroidBuildActions(ctx ModuleContext) {
 func (s *sourceModule) Srcs() Paths {
 	return Paths{s.src}
 }
+
+type overrideSourceModule struct {
+	ModuleBase
+	OverrideModuleBase
+}
+
+func (o *overrideSourceModule) GenerateAndroidBuildActions(_ ModuleContext) {
+}
+
+func newOverrideSourceModule() Module {
+	m := &overrideSourceModule{}
+	m.AddProperties(&sourceModuleProperties{})
+
+	InitAndroidArchModule(m, HostAndDeviceDefault, MultilibCommon)
+	InitOverrideModule(m)
+	return m
+}