Convert android.TransitionMutator to TransitionInfo

Use the ApexInfo instead of a string as the TransitionInfo for apex
variations.  This removes the need for apexInfoMutator, which is the
last remaining top down mutator.

This has a variety of ramifications.  One is that it is no longer
possible to add a dependency onto the apex variation of a module,
as that would require constructing a matching ApexInfo.  Instead,
anything that wants to add a dependency on the apex variation has
to depend on the apex instead, and get to the module by walking
its transistive dependencies.

Another ramification is that modules in apexes can no longer
determine which apexes they are in (unless they set
UniqueApexVariations so that each variation is in exactly one
apex).  This prevents some of the existing container violation
checks from working after this CL, tracked in b/394955484.

It also requires using unique variation names for the prebuilt
and source dependencies of apexes, so the apex variations
for dependencies of prebuilts now have a prebuilt_ prefix.

Bug: 372543712
Bug: 394955484
Test: go test ./...
Change-Id: I3d08aca1ac956ab0e343ec3f235a736cd93be0e1

1 files changed, 57 insertions, 111 deletions

diff --git a/apex/apex.go b/apex/apex.go
index 24b3118a4..33538fb13 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -61,12 +61,11 @@ func RegisterPreDepsMutators(ctx android.RegisterMutatorsContext) {
 }
 
 func RegisterPostDepsMutators(ctx android.RegisterMutatorsContext) {
-	ctx.TopDown("apex_info", apexInfoMutator)
 	ctx.BottomUp("apex_unique", apexUniqueVariationsMutator)
 	// Run mark_platform_availability before the apexMutator as the apexMutator needs to know whether
 	// it should create a platform variant.
 	ctx.BottomUp("mark_platform_availability", markPlatformAvailability)
-	ctx.Transition("apex", &apexTransitionMutator{})
+	ctx.InfoBasedTransition("apex", android.NewGenericTransitionMutatorAdapter(&apexTransitionMutator{}))
 }
 
 type apexBundleProperties struct {
@@ -996,45 +995,29 @@ func (a *apexBundle) OverridablePropertiesDepsMutator(ctx android.BottomUpMutato
 	}
 }
 
-var _ ApexInfoMutator = (*apexBundle)(nil)
+var _ ApexTransitionMutator = (*apexBundle)(nil)
 
 func (a *apexBundle) ApexVariationName() string {
 	return a.properties.ApexVariationName
 }
 
-// ApexInfoMutator is responsible for collecting modules that need to have apex variants. They are
-// identified by doing a graph walk starting from an apexBundle. Basically, all the (direct and
-// indirect) dependencies are collected. But a few types of modules that shouldn't be included in
-// the apexBundle (e.g. stub libraries) are not collected. Note that a single module can be depended
-// on by multiple apexBundles. In that case, the module is collected for all of the apexBundles.
-//
-// For each dependency between an apex and an ApexModule an ApexInfo object describing the apex
-// is passed to that module's BuildForApex(ApexInfo) method which collates them all in a list.
-// The apexMutator uses that list to create module variants for the apexes to which it belongs.
-// The relationship between module variants and apexes is not one-to-one as variants will be
-// shared between compatible apexes.
-func (a *apexBundle) ApexInfoMutator(mctx android.TopDownMutatorContext) {
+type generateApexInfoContext interface {
+	android.MinSdkVersionFromValueContext
+	Module() android.Module
+	ModuleName() string
+}
 
+// generateApexInfo returns an android.ApexInfo configuration that should be used for dependencies of this apex.
+func (a *apexBundle) generateApexInfo(ctx generateApexInfoContext) android.ApexInfo {
 	// The VNDK APEX is special. For the APEX, the membership is described in a very different
 	// way. There is no dependency from the VNDK APEX to the VNDK libraries. Instead, VNDK
 	// libraries are self-identified by their vndk.enabled properties. There is no need to run
-	// this mutator for the APEX as nothing will be collected. So, let's return fast.
+	// this mutator for the APEX as nothing will be collected so return an empty ApexInfo.
 	if a.vndkApex {
-		return
-	}
-
-	continueApexDepsWalk := func(child, parent android.Module) bool {
-		am, ok := child.(android.ApexModule)
-		if !ok || !am.CanHaveApexVariants() {
-			return false
-		}
-
-		return android.IsDepInSameApex(mctx, parent, child)
+		return android.ApexInfo{}
 	}
 
-	android.SetProvider(mctx, android.ApexBundleInfoProvider, android.ApexBundleInfo{})
-
-	minSdkVersion := a.minSdkVersion(mctx)
+	minSdkVersion := a.minSdkVersion(ctx)
 	// When min_sdk_version is not set, the apex is built against FutureApiLevel.
 	if minSdkVersion.IsNone() {
 		minSdkVersion = android.FutureApiLevel
@@ -1043,62 +1026,45 @@ func (a *apexBundle) ApexInfoMutator(mctx android.TopDownMutatorContext) {
 	// This is the main part of this mutator. Mark the collected dependencies that they need to
 	// be built for this apexBundle.
 
-	apexVariationName := mctx.ModuleName() // could be com.android.foo
+	apexVariationName := ctx.ModuleName() // could be com.android.foo
 	if a.GetOverriddenBy() != "" {
 		// use the overridden name com.mycompany.android.foo
 		apexVariationName = a.GetOverriddenBy()
 	}
 
-	a.properties.ApexVariationName = apexVariationName
 	apexInfo := android.ApexInfo{
 		ApexVariationName: apexVariationName,
 		MinSdkVersion:     minSdkVersion,
 		Updatable:         a.Updatable(),
 		UsePlatformApis:   a.UsePlatformApis(),
-		InApexVariants:    []string{apexVariationName},
-		BaseApexName:      mctx.ModuleName(),
+		BaseApexName:      ctx.ModuleName(),
 		ApexAvailableName: proptools.String(a.properties.Apex_available_name),
 	}
-	mctx.WalkDeps(func(child, parent android.Module) bool {
-		if parent == mctx.Module() {
-			tag := mctx.OtherModuleDependencyTag(child)
-			if _, ok := tag.(*dependencyTag); !ok {
-				return false
-			}
-		}
-		if !continueApexDepsWalk(child, parent) {
-			return false
-		}
-		child.(android.ApexModule).BuildForApex(apexInfo) // leave a mark!
-		return true
-	})
+	return apexInfo
 }
 
-type ApexInfoMutator interface {
-	// ApexVariationName returns the name of the APEX variation to use in the apex
-	// mutator etc. It is the same name as ApexInfo.ApexVariationName.
-	ApexVariationName() string
+func (a *apexBundle) ApexTransitionMutatorSplit(ctx android.BaseModuleContext) []android.ApexInfo {
+	return []android.ApexInfo{a.generateApexInfo(ctx)}
+}
 
-	// ApexInfoMutator implementations must call BuildForApex(ApexInfo) on any modules that are
-	// depended upon by an apex and which require an apex specific variant.
-	ApexInfoMutator(android.TopDownMutatorContext)
+func (a *apexBundle) ApexTransitionMutatorOutgoing(ctx android.OutgoingTransitionContext, sourceInfo android.ApexInfo) android.ApexInfo {
+	return sourceInfo
 }
 
-// apexInfoMutator delegates the work of identifying which modules need an ApexInfo and apex
-// specific variant to modules that support the ApexInfoMutator.
-// It also propagates updatable=true to apps of updatable apexes
-func apexInfoMutator(mctx android.TopDownMutatorContext) {
-	if !mctx.Module().Enabled(mctx) {
-		return
-	}
+func (a *apexBundle) ApexTransitionMutatorIncoming(ctx android.IncomingTransitionContext, outgoingInfo android.ApexInfo) android.ApexInfo {
+	return a.generateApexInfo(ctx)
+}
 
-	if a, ok := mctx.Module().(ApexInfoMutator); ok {
-		a.ApexInfoMutator(mctx)
-	}
+func (a *apexBundle) ApexTransitionMutatorMutate(ctx android.BottomUpMutatorContext, info android.ApexInfo) {
+	android.SetProvider(ctx, android.ApexBundleInfoProvider, android.ApexBundleInfo{})
+	a.properties.ApexVariationName = info.ApexVariationName
+}
 
-	if am, ok := mctx.Module().(android.ApexModule); ok {
-		android.ApexInfoMutator(mctx, am)
-	}
+type ApexTransitionMutator interface {
+	ApexTransitionMutatorSplit(ctx android.BaseModuleContext) []android.ApexInfo
+	ApexTransitionMutatorOutgoing(ctx android.OutgoingTransitionContext, sourceInfo android.ApexInfo) android.ApexInfo
+	ApexTransitionMutatorIncoming(ctx android.IncomingTransitionContext, outgoingInfo android.ApexInfo) android.ApexInfo
+	ApexTransitionMutatorMutate(ctx android.BottomUpMutatorContext, info android.ApexInfo)
 }
 
 // TODO: b/215736885 Whittle the denylist
@@ -1213,49 +1179,35 @@ func markPlatformAvailability(mctx android.BottomUpMutatorContext) {
 
 type apexTransitionMutator struct{}
 
-func (a *apexTransitionMutator) Split(ctx android.BaseModuleContext) []string {
-	// apexBundle itself is mutated so that it and its dependencies have the same apex variant.
-	if ai, ok := ctx.Module().(ApexInfoMutator); ok && apexModuleTypeRequiresVariant(ai) {
-		if overridable, ok := ctx.Module().(android.OverridableModule); ok && overridable.GetOverriddenBy() != "" {
-			return []string{overridable.GetOverriddenBy()}
-		}
-		return []string{ai.ApexVariationName()}
+func (a *apexTransitionMutator) Split(ctx android.BaseModuleContext) []android.ApexInfo {
+	if ai, ok := ctx.Module().(ApexTransitionMutator); ok {
+		return ai.ApexTransitionMutatorSplit(ctx)
 	}
-	return []string{""}
+	return []android.ApexInfo{{}}
 }
 
-func (a *apexTransitionMutator) OutgoingTransition(ctx android.OutgoingTransitionContext, sourceVariation string) string {
-	return sourceVariation
-}
-
-func (a *apexTransitionMutator) IncomingTransition(ctx android.IncomingTransitionContext, incomingVariation string) string {
-	if am, ok := ctx.Module().(android.ApexModule); ok && am.CanHaveApexVariants() {
-		return android.IncomingApexTransition(ctx, incomingVariation)
-	} else if ai, ok := ctx.Module().(ApexInfoMutator); ok {
-		if overridable, ok := ctx.Module().(android.OverridableModule); ok && overridable.GetOverriddenBy() != "" {
-			return overridable.GetOverriddenBy()
-		}
-		return ai.ApexVariationName()
+func (a *apexTransitionMutator) OutgoingTransition(ctx android.OutgoingTransitionContext, sourceInfo android.ApexInfo) android.ApexInfo {
+	if ai, ok := ctx.Module().(ApexTransitionMutator); ok {
+		return ai.ApexTransitionMutatorOutgoing(ctx, sourceInfo)
 	}
-
-	return ""
+	return android.ApexInfo{}
 }
 
-func (a *apexTransitionMutator) Mutate(ctx android.BottomUpMutatorContext, variation string) {
-	if am, ok := ctx.Module().(android.ApexModule); ok && am.CanHaveApexVariants() {
-		android.MutateApexTransition(ctx, variation)
+func (a *apexTransitionMutator) IncomingTransition(ctx android.IncomingTransitionContext, outgoingInfo android.ApexInfo) android.ApexInfo {
+	if ai, ok := ctx.Module().(ApexTransitionMutator); ok {
+		return ai.ApexTransitionMutatorIncoming(ctx, outgoingInfo)
 	}
+	return android.ApexInfo{}
 }
 
-// apexModuleTypeRequiresVariant determines whether the module supplied requires an apex specific
-// variant.
-func apexModuleTypeRequiresVariant(module ApexInfoMutator) bool {
-	if a, ok := module.(*apexBundle); ok {
-		// TODO(jiyong): document the reason why the VNDK APEX is an exception here.
-		return !a.vndkApex
+func (a *apexTransitionMutator) Mutate(ctx android.BottomUpMutatorContext, info android.ApexInfo) {
+	if ai, ok := ctx.Module().(ApexTransitionMutator); ok {
+		ai.ApexTransitionMutatorMutate(ctx, info)
 	}
+}
 
-	return true
+func (a *apexTransitionMutator) TransitionInfoFromVariation(variation string) android.ApexInfo {
+	panic(fmt.Errorf("adding dependencies on explicit apex variations is not supported"))
 }
 
 const (
@@ -1677,10 +1629,6 @@ func apexFileForFilesystem(ctx android.BaseModuleContext, buildFile android.Path
 // to the child modules. Returning false makes the visit to continue in the sibling or the parent
 // modules. This is used in check* functions below.
 func (a *apexBundle) WalkPayloadDeps(ctx android.BaseModuleContext, do android.PayloadDepsCallback) {
-	apexVariationName := ctx.ModuleName()
-	if overrideName := a.GetOverriddenBy(); overrideName != "" {
-		apexVariationName = overrideName
-	}
 	ctx.WalkDeps(func(child, parent android.Module) bool {
 		am, ok := child.(android.ApexModule)
 		if !ok || !am.CanHaveApexVariants() {
@@ -1699,8 +1647,7 @@ func (a *apexBundle) WalkPayloadDeps(ctx android.BaseModuleContext, do android.P
 			return false
 		}
 
-		ai, _ := android.OtherModuleProvider(ctx, child, android.ApexInfoProvider)
-		externalDep := !android.InList(apexVariationName, ai.InApexVariants)
+		externalDep := !android.IsDepInSameApex(ctx, parent, child)
 
 		// Visit actually
 		return do(ctx, parent, am, externalDep)
@@ -1725,8 +1672,7 @@ func (a *apexBundle) WalkPayloadDepsProxy(ctx android.BaseModuleContext,
 			return false
 		}
 
-		ai, _ := android.OtherModuleProvider(ctx, child, android.ApexInfoProvider)
-		externalDep := !android.InList(ctx.ModuleName(), ai.InApexVariants)
+		externalDep := !android.IsDepInSameApex(ctx, parent, child)
 
 		// Visit actually
 		return do(ctx, parent, child, externalDep)
@@ -2573,7 +2519,7 @@ func (a *apexBundle) CheckMinSdkVersion(ctx android.ModuleContext) {
 }
 
 // Returns apex's min_sdk_version string value, honoring overrides
-func (a *apexBundle) minSdkVersionValue(ctx android.EarlyModuleContext) string {
+func (a *apexBundle) minSdkVersionValue(ctx android.MinSdkVersionFromValueContext) string {
 	// Only override the minSdkVersion value on Apexes which already specify
 	// a min_sdk_version (it's optional for non-updatable apexes), and that its
 	// min_sdk_version value is lower than the one to override with.
@@ -2597,7 +2543,7 @@ func (a *apexBundle) MinSdkVersion(ctx android.EarlyModuleContext) android.ApiLe
 }
 
 // Returns apex's min_sdk_version ApiLevel, honoring overrides
-func (a *apexBundle) minSdkVersion(ctx android.EarlyModuleContext) android.ApiLevel {
+func (a *apexBundle) minSdkVersion(ctx android.MinSdkVersionFromValueContext) android.ApiLevel {
 	return android.MinSdkVersionFromValue(ctx, a.minSdkVersionValue(ctx))
 }
 
@@ -2613,7 +2559,7 @@ func (a *apexBundle) checkStaticLinkingToStubLibraries(ctx android.ModuleContext
 		librariesDirectlyInApex[ctx.OtherModuleName(dep)] = true
 	})
 
-	a.WalkPayloadDepsProxy(ctx, func(ctx android.BaseModuleContext, from, to android.ModuleProxy, externalDep bool) bool {
+	a.WalkPayloadDeps(ctx, func(ctx android.BaseModuleContext, from android.Module, to android.ApexModule, externalDep bool) bool {
 		if info, ok := android.OtherModuleProvider(ctx, to, cc.LinkableInfoProvider); ok {
 			// If `to` is not actually in the same APEX as `from` then it does not need
 			// apex_available and neither do any of its dependencies.
@@ -2727,7 +2673,7 @@ func (a *apexBundle) checkApexAvailability(ctx android.ModuleContext) {
 		return
 	}
 
-	a.WalkPayloadDepsProxy(ctx, func(ctx android.BaseModuleContext, from, to android.ModuleProxy, externalDep bool) bool {
+	a.WalkPayloadDeps(ctx, func(ctx android.BaseModuleContext, from android.Module, to android.ApexModule, externalDep bool) bool {
 		// As soon as the dependency graph crosses the APEX boundary, don't go further.
 		if externalDep {
 			return false
@@ -2745,7 +2691,7 @@ func (a *apexBundle) checkApexAvailability(ctx android.ModuleContext) {
 		toName := ctx.OtherModuleName(to)
 
 		if android.CheckAvailableForApex(apexName,
-			android.OtherModuleProviderOrDefault(ctx, to, android.ApexInfoProvider).ApexAvailableFor) {
+			android.OtherModuleProviderOrDefault(ctx, to, android.ApexAvailableInfoProvider).ApexAvailableFor) {
 			return true
 		}