diff --git a/cc/ccdeps.go b/cc/ccdeps.go
index b96d8b0..75e1faf 100644
--- a/cc/ccdeps.go
+++ b/cc/ccdeps.go
@@ -44,11 +44,9 @@
 var _ android.SingletonMakeVarsProvider = (*ccdepsGeneratorSingleton)(nil)
 
 const (
-	// Environment variables used to control the behavior of this singleton.
-	envVariableCollectCCDeps = "SOONG_COLLECT_CC_DEPS"
-	ccdepsJsonFileName       = "module_bp_cc_deps.json"
-	cClang                   = "clang"
-	cppClang                 = "clang++"
+	ccdepsJsonFileName = "module_bp_cc_deps.json"
+	cClang             = "clang"
+	cppClang           = "clang++"
 )
 
 type ccIdeInfo struct {
@@ -83,10 +81,7 @@
 }
 
 func (c *ccdepsGeneratorSingleton) GenerateBuildActions(ctx android.SingletonContext) {
-	if !ctx.Config().IsEnvTrue(envVariableCollectCCDeps) {
-		return
-	}
-
+	// (b/204397180) Generate module_bp_cc_deps.json by default.
 	moduleDeps := ccDeps{}
 	moduleInfos := map[string]ccIdeInfo{}
 
diff --git a/java/androidmk.go b/java/androidmk.go
index 35b4c8e..4c115d5 100644
--- a/java/androidmk.go
+++ b/java/androidmk.go
@@ -47,6 +47,7 @@
 					if library.dexJarFile.IsSet() {
 						entries.SetPath("LOCAL_SOONG_DEX_JAR", library.dexJarFile.Path())
 					}
+					entries.SetPath("LOCAL_SOONG_INSTALLED_MODULE", library.hostdexInstallFile)
 					entries.SetPath("LOCAL_SOONG_HEADER_JAR", library.headerJarFile)
 					entries.SetPath("LOCAL_SOONG_CLASSES_JAR", library.implementationAndResourcesJar)
 					entries.SetString("LOCAL_MODULE_STEM", library.Stem()+"-hostdex")
diff --git a/java/app.go b/java/app.go
index 7c195fc..c08ec06 100755
--- a/java/app.go
+++ b/java/app.go
@@ -471,6 +471,7 @@
 	a.dexpreopter.enforceUsesLibs = a.usesLibrary.enforceUsesLibraries()
 	a.dexpreopter.classLoaderContexts = a.classLoaderContexts
 	a.dexpreopter.manifestFile = a.mergedManifestFile
+	a.dexpreopter.preventInstall = a.appProperties.PreventInstall
 
 	if ctx.ModuleName() != "framework-res" {
 		a.Module.compile(ctx, a.aaptSrcJar)
@@ -720,7 +721,9 @@
 	apexInfo := ctx.Provider(android.ApexInfoProvider).(android.ApexInfo)
 
 	// Install the app package.
-	if (Bool(a.Module.properties.Installable) || ctx.Host()) && apexInfo.IsForPlatform() {
+	if (Bool(a.Module.properties.Installable) || ctx.Host()) && apexInfo.IsForPlatform() &&
+		!a.appProperties.PreventInstall {
+
 		var extraInstalledPaths android.Paths
 		for _, extra := range a.extraOutputFiles {
 			installed := ctx.InstallFile(a.installDir, extra.Base(), extra)
diff --git a/java/base.go b/java/base.go
index 859baaf..6930bcd 100644
--- a/java/base.go
+++ b/java/base.go
@@ -407,6 +407,9 @@
 	// installed file for binary dependency
 	installFile android.Path
 
+	// installed file for hostdex copy
+	hostdexInstallFile android.InstallPath
+
 	// list of .java files and srcjars that was passed to javac
 	compiledJavaSrcs android.Paths
 	compiledSrcJars  android.Paths
diff --git a/java/dexpreopt.go b/java/dexpreopt.go
index 8ab5a45..7c081b6 100644
--- a/java/dexpreopt.go
+++ b/java/dexpreopt.go
@@ -66,6 +66,7 @@
 	isApp               bool
 	isTest              bool
 	isPresignedPrebuilt bool
+	preventInstall      bool
 
 	manifestFile        android.Path
 	statusFile          android.WritablePath
@@ -356,7 +357,7 @@
 				installDirOnDevice:  installPath,
 				installFileOnDevice: installBase,
 			})
-		} else {
+		} else if !d.preventInstall {
 			ctx.InstallFile(installPath, installBase, install.From)
 		}
 	}
diff --git a/java/java.go b/java/java.go
index 3bb9a92..2f9e03a 100644
--- a/java/java.go
+++ b/java/java.go
@@ -571,7 +571,8 @@
 		}
 		hostDexNeeded := Bool(j.deviceProperties.Hostdex) && !ctx.Host()
 		if hostDexNeeded {
-			ctx.InstallFile(android.PathForHostDexInstall(ctx, "framework"),
+			j.hostdexInstallFile = ctx.InstallFile(
+				android.PathForHostDexInstall(ctx, "framework"),
 				j.Stem()+"-hostdex.jar", j.outputFile)
 		}
 		var installDir android.InstallPath
diff --git a/java/jdeps.go b/java/jdeps.go
index 0ab2e42..eff9a31 100644
--- a/java/jdeps.go
+++ b/java/jdeps.go
@@ -40,16 +40,11 @@
 var _ android.SingletonMakeVarsProvider = (*jdepsGeneratorSingleton)(nil)
 
 const (
-	// Environment variables used to modify behavior of this singleton.
-	envVariableCollectJavaDeps = "SOONG_COLLECT_JAVA_DEPS"
-	jdepsJsonFileName          = "module_bp_java_deps.json"
+	jdepsJsonFileName = "module_bp_java_deps.json"
 )
 
 func (j *jdepsGeneratorSingleton) GenerateBuildActions(ctx android.SingletonContext) {
-	if !ctx.Config().IsEnvTrue(envVariableCollectJavaDeps) {
-		return
-	}
-
+	// (b/204397180) Generate module_bp_java_deps.json by default.
 	moduleInfos := make(map[string]android.IdeInfo)
 
 	ctx.VisitAllModules(func(module android.Module) {
diff --git a/mk2rbc/mk2rbc.go b/mk2rbc/mk2rbc.go
index 55835c1..0e39c32 100644
--- a/mk2rbc/mk2rbc.go
+++ b/mk2rbc/mk2rbc.go
@@ -540,6 +540,14 @@
 		return
 	}
 	name := a.Name.Strings[0]
+	// The `override` directive
+	//      override FOO :=
+	// is parsed as an assignment to a variable named `override FOO`.
+	// There are very few places where `override` is used, just flag it.
+	if strings.HasPrefix(name, "override ") {
+		ctx.errorf(a, "cannot handle override directive")
+	}
+
 	// Soong configuration
 	if strings.HasPrefix(name, soongNsPrefix) {
 		ctx.handleSoongNsAssignment(strings.TrimPrefix(name, soongNsPrefix), a)
diff --git a/mk2rbc/mk2rbc_test.go b/mk2rbc/mk2rbc_test.go
index 80a482f..1e79552 100644
--- a/mk2rbc/mk2rbc_test.go
+++ b/mk2rbc/mk2rbc_test.go
@@ -1027,6 +1027,21 @@
   rblf.warning("product.mk", "partially successful conversion")
 `,
 	},
+	{
+		desc:   "Flag override",
+		mkname: "product.mk",
+		in: `
+override FOO:=`,
+		expected: `# MK2RBC TRANSLATION ERROR: cannot handle override directive
+# override FOO :=
+load("//build/make/core:product_config.rbc", "rblf")
+
+def init(g, handle):
+  cfg = rblf.cfg(handle)
+  g["override FOO"] = ""
+  rblf.warning("product.mk", "partially successful conversion")
+`,
+	},
 }
 
 var known_variables = []struct {
diff --git a/rust/config/global.go b/rust/config/global.go
index b163bb6..ebddb75 100644
--- a/rust/config/global.go
+++ b/rust/config/global.go
@@ -24,7 +24,7 @@
 var pctx = android.NewPackageContext("android/soong/rust/config")
 
 var (
-	RustDefaultVersion = "1.55.0"
+	RustDefaultVersion = "1.56.1"
 	RustDefaultBase    = "prebuilts/rust/"
 	DefaultEdition     = "2018"
 	Stdlibs            = []string{