Skip building compat files if REL

Bug: 296780580
Test: build with next
Change-Id: I588d249f35fc7049d0db3b64692ed818050af0ed
diff --git a/build/soong/compat_cil.go b/build/soong/compat_cil.go
index 881f7da..1f7901b 100644
--- a/build/soong/compat_cil.go
+++ b/build/soong/compat_cil.go
@@ -43,7 +43,7 @@
 type compatCil struct {
 	android.ModuleBase
 	properties    compatCilProperties
-	installSource android.Path
+	installSource android.OptionalPath
 	installPath   android.InstallPath
 }
 
@@ -53,6 +53,10 @@
 
 	// Output file name. Defaults to module name if unspecified.
 	Stem *string
+
+	// Target version that this module supports. This module will be ignored if platform sepolicy
+	// version is same as this module's version.
+	Version *string
 }
 
 func (c *compatCil) stem() string {
@@ -63,11 +67,19 @@
 	return android.PathsForModuleSrc(ctx, c.properties.Srcs)
 }
 
+func (c *compatCil) shouldSkipBuild(ctx android.ModuleContext) bool {
+	return proptools.String(c.properties.Version) == ctx.DeviceConfig().PlatformSepolicyVersion()
+}
+
 func (c *compatCil) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 	if c.ProductSpecific() || c.SocSpecific() || c.DeviceSpecific() {
 		ctx.ModuleErrorf("Compat cil files only support system and system_ext partitions")
 	}
 
+	if c.shouldSkipBuild(ctx) {
+		return
+	}
+
 	srcPaths := c.expandSeSources(ctx)
 	out := android.PathForModuleGen(ctx, c.Name())
 	ctx.Build(pctx, android.BuildParams{
@@ -78,14 +90,17 @@
 	})
 
 	c.installPath = android.PathForModuleInstall(ctx, "etc", "selinux", "mapping")
-	c.installSource = out
-	ctx.InstallFile(c.installPath, c.stem(), c.installSource)
+	c.installSource = android.OptionalPathForPath(out)
+	ctx.InstallFile(c.installPath, c.stem(), out)
 }
 
 func (c *compatCil) AndroidMkEntries() []android.AndroidMkEntries {
+	if !c.installSource.Valid() {
+		return nil
+	}
 	return []android.AndroidMkEntries{android.AndroidMkEntries{
 		Class:      "ETC",
-		OutputFile: android.OptionalPathForPath(c.installSource),
+		OutputFile: c.installSource,
 		ExtraEntries: []android.AndroidMkExtraEntriesFunc{
 			func(ctx android.AndroidMkExtraEntriesContext, entries *android.AndroidMkEntries) {
 				entries.SetPath("LOCAL_MODULE_PATH", c.installPath)
@@ -98,7 +113,11 @@
 func (c *compatCil) OutputFiles(tag string) (android.Paths, error) {
 	switch tag {
 	case "":
-		return android.Paths{c.installSource}, nil
+		if c.installSource.Valid() {
+			return android.Paths{c.installSource.Path()}, nil
+		} else {
+			return nil, nil
+		}
 	default:
 		return nil, fmt.Errorf("unsupported module reference tag %q", tag)
 	}