Merge "Only package gcno files for gcov coverage builds."
diff --git a/apex/apex.go b/apex/apex.go
index 3542c6a..8463ac1 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -1741,15 +1741,16 @@
 func apexFileForAndroidApp(ctx android.BaseModuleContext, aapp interface {
 	android.Module
 	Privileged() bool
+	InstallApkName() string
 	OutputFile() android.Path
 	JacocoReportClassesFile() android.Path
 	Certificate() java.Certificate
-}, pkgName string) apexFile {
+}) apexFile {
 	appDir := "app"
 	if aapp.Privileged() {
 		appDir = "priv-app"
 	}
-	dirInApex := filepath.Join(appDir, pkgName)
+	dirInApex := filepath.Join(appDir, aapp.InstallApkName())
 	fileToCopy := aapp.OutputFile()
 	af := newApexFile(ctx, fileToCopy, aapp.Name(), dirInApex, app, aapp)
 	af.jacocoReportClassesFile = aapp.JacocoReportClassesFile()
@@ -2040,14 +2041,13 @@
 					ctx.PropertyErrorf("java_libs", "%q of type %q is not supported", depName, ctx.OtherModuleType(child))
 				}
 			case androidAppTag:
-				pkgName := ctx.DeviceConfig().OverridePackageNameFor(depName)
 				if ap, ok := child.(*java.AndroidApp); ok {
-					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap, pkgName))
+					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap))
 					return true // track transitive dependencies
 				} else if ap, ok := child.(*java.AndroidAppImport); ok {
-					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap, pkgName))
+					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap))
 				} else if ap, ok := child.(*java.AndroidTestHelperApp); ok {
-					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap, pkgName))
+					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap))
 				} else {
 					ctx.PropertyErrorf("apps", "%q is not an android_app module", depName)
 				}
diff --git a/apex/apex_test.go b/apex/apex_test.go
index cbff0f1..9f55728 100644
--- a/apex/apex_test.go
+++ b/apex/apex_test.go
@@ -3438,6 +3438,7 @@
 			dex_preopt: {
 				enabled: false,
 			},
+			filename: "AwesomePrebuiltAppFooPriv.apk",
 		}
 	`)
 
@@ -3446,7 +3447,47 @@
 	copyCmds := apexRule.Args["copy_commands"]
 
 	ensureContains(t, copyCmds, "image.apex/app/AppFooPrebuilt/AppFooPrebuilt.apk")
-	ensureContains(t, copyCmds, "image.apex/priv-app/AppFooPrivPrebuilt/AppFooPrivPrebuilt.apk")
+	ensureContains(t, copyCmds, "image.apex/priv-app/AppFooPrivPrebuilt/AwesomePrebuiltAppFooPriv.apk")
+}
+
+func TestApexWithAppImportsPrefer(t *testing.T) {
+	ctx, _ := testApex(t, `
+		apex {
+			name: "myapex",
+			key: "myapex.key",
+			apps: [
+				"AppFoo",
+			],
+		}
+
+		apex_key {
+			name: "myapex.key",
+			public_key: "testkey.avbpubkey",
+			private_key: "testkey.pem",
+		}
+
+		android_app {
+			name: "AppFoo",
+			srcs: ["foo/bar/MyClass.java"],
+			sdk_version: "none",
+			system_modules: "none",
+			apex_available: [ "myapex" ],
+		}
+
+		android_app_import {
+			name: "AppFoo",
+			apk: "AppFooPrebuilt.apk",
+			filename: "AppFooPrebuilt.apk",
+			presigned: true,
+			prefer: true,
+		}
+	`, withFiles(map[string][]byte{
+		"AppFooPrebuilt.apk": nil,
+	}))
+
+	ensureExactContents(t, ctx, "myapex", "android_common_myapex_image", []string{
+		"app/AppFoo/AppFooPrebuilt.apk",
+	})
 }
 
 func TestApexWithTestHelperApp(t *testing.T) {
@@ -3779,7 +3820,7 @@
 	copyCmds := apexRule.Args["copy_commands"]
 
 	ensureNotContains(t, copyCmds, "image.apex/app/app/app.apk")
-	ensureContains(t, copyCmds, "image.apex/app/app/override_app.apk")
+	ensureContains(t, copyCmds, "image.apex/app/override_app/override_app.apk")
 
 	apexBundle := module.Module().(*apexBundle)
 	name := apexBundle.Name()
diff --git a/cc/cc.go b/cc/cc.go
index 731f288..63aab95 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -213,6 +213,9 @@
 	// two variants to be built, one for the platform and one for apps.
 	Sdk_version *string
 
+	// Minimum sdk version that the artifact should support when it runs as part of mainline modules(APEX).
+	Min_sdk_version *string
+
 	// If true, always create an sdk variant and don't create a platform variant.
 	Sdk_variant_only *bool
 
@@ -1195,6 +1198,11 @@
 		return false
 	}
 
+	// Coverage builds have extra symbols.
+	if ctx.mod.isCoverageVariant() {
+		return false
+	}
+
 	if ctx.ctx.Fuchsia() {
 		return false
 	}
diff --git a/java/androidmk.go b/java/androidmk.go
index d37eac8..7d57525 100644
--- a/java/androidmk.go
+++ b/java/androidmk.go
@@ -472,34 +472,6 @@
 				if ddoc.Javadoc.stubsSrcJar != nil {
 					entries.SetPath("LOCAL_DROIDDOC_STUBS_SRCJAR", ddoc.Javadoc.stubsSrcJar)
 				}
-				apiFilePrefix := "INTERNAL_PLATFORM_"
-				if String(ddoc.properties.Api_tag_name) != "" {
-					apiFilePrefix += String(ddoc.properties.Api_tag_name) + "_"
-				}
-				if ddoc.apiFile != nil {
-					entries.SetPath(apiFilePrefix+"API_FILE", ddoc.apiFile)
-				}
-				if ddoc.dexApiFile != nil {
-					entries.SetPath(apiFilePrefix+"DEX_API_FILE", ddoc.dexApiFile)
-				}
-				if ddoc.privateApiFile != nil {
-					entries.SetPath(apiFilePrefix+"PRIVATE_API_FILE", ddoc.privateApiFile)
-				}
-				if ddoc.privateDexApiFile != nil {
-					entries.SetPath(apiFilePrefix+"PRIVATE_DEX_API_FILE", ddoc.privateDexApiFile)
-				}
-				if ddoc.removedApiFile != nil {
-					entries.SetPath(apiFilePrefix+"REMOVED_API_FILE", ddoc.removedApiFile)
-				}
-				if ddoc.removedDexApiFile != nil {
-					entries.SetPath(apiFilePrefix+"REMOVED_DEX_API_FILE", ddoc.removedDexApiFile)
-				}
-				if ddoc.exactApiFile != nil {
-					entries.SetPath(apiFilePrefix+"EXACT_API_FILE", ddoc.exactApiFile)
-				}
-				if ddoc.proguardFile != nil {
-					entries.SetPath(apiFilePrefix+"PROGUARD_FILE", ddoc.proguardFile)
-				}
 			},
 		},
 		ExtraFooters: []android.AndroidMkExtraFootersFunc{
@@ -578,35 +550,18 @@
 				if dstubs.metadataZip != nil {
 					entries.SetPath("LOCAL_DROIDDOC_METADATA_ZIP", dstubs.metadataZip)
 				}
-				apiFilePrefix := "INTERNAL_PLATFORM_"
-				if String(dstubs.properties.Api_tag_name) != "" {
-					apiFilePrefix += String(dstubs.properties.Api_tag_name) + "_"
-				}
-				if dstubs.apiFile != nil {
-					entries.SetPath(apiFilePrefix+"API_FILE", dstubs.apiFile)
-				}
-				if dstubs.dexApiFile != nil {
-					entries.SetPath(apiFilePrefix+"DEX_API_FILE", dstubs.dexApiFile)
-				}
-				if dstubs.privateApiFile != nil {
-					entries.SetPath(apiFilePrefix+"PRIVATE_API_FILE", dstubs.privateApiFile)
-				}
-				if dstubs.privateDexApiFile != nil {
-					entries.SetPath(apiFilePrefix+"PRIVATE_DEX_API_FILE", dstubs.privateDexApiFile)
-				}
-				if dstubs.removedApiFile != nil {
-					entries.SetPath(apiFilePrefix+"REMOVED_API_FILE", dstubs.removedApiFile)
-				}
-				if dstubs.removedDexApiFile != nil {
-					entries.SetPath(apiFilePrefix+"REMOVED_DEX_API_FILE", dstubs.removedDexApiFile)
-				}
-				if dstubs.exactApiFile != nil {
-					entries.SetPath(apiFilePrefix+"EXACT_API_FILE", dstubs.exactApiFile)
-				}
 			},
 		},
 		ExtraFooters: []android.AndroidMkExtraFootersFunc{
 			func(w io.Writer, name, prefix, moduleDir string, entries *android.AndroidMkEntries) {
+				if dstubs.apiFile != nil {
+					fmt.Fprintf(w, ".PHONY: %s %s.txt\n", dstubs.Name(), dstubs.Name())
+					fmt.Fprintf(w, "%s %s.txt: %s\n", dstubs.Name(), dstubs.Name(), dstubs.apiFile)
+				}
+				if dstubs.removedApiFile != nil {
+					fmt.Fprintf(w, ".PHONY: %s %s.txt\n", dstubs.Name(), dstubs.Name())
+					fmt.Fprintf(w, "%s %s.txt: %s\n", dstubs.Name(), dstubs.Name(), dstubs.removedApiFile)
+				}
 				if dstubs.checkCurrentApiTimestamp != nil {
 					fmt.Fprintln(w, ".PHONY:", dstubs.Name()+"-check-current-api")
 					fmt.Fprintln(w, dstubs.Name()+"-check-current-api:",
@@ -633,14 +588,12 @@
 					fmt.Fprintln(w, dstubs.Name()+"-check-last-released-api:",
 						dstubs.checkLastReleasedApiTimestamp.String())
 
-					if dstubs.Name() != "android.car-system-stubs-docs" {
-						fmt.Fprintln(w, ".PHONY: checkapi")
-						fmt.Fprintln(w, "checkapi:",
-							dstubs.checkLastReleasedApiTimestamp.String())
+					fmt.Fprintln(w, ".PHONY: checkapi")
+					fmt.Fprintln(w, "checkapi:",
+						dstubs.checkLastReleasedApiTimestamp.String())
 
-						fmt.Fprintln(w, ".PHONY: droidcore")
-						fmt.Fprintln(w, "droidcore: checkapi")
-					}
+					fmt.Fprintln(w, ".PHONY: droidcore")
+					fmt.Fprintln(w, "droidcore: checkapi")
 				}
 				if dstubs.apiLintTimestamp != nil {
 					fmt.Fprintln(w, ".PHONY:", dstubs.Name()+"-api-lint")
diff --git a/java/app.go b/java/app.go
index ac5121a..7d509ee 100755
--- a/java/app.go
+++ b/java/app.go
@@ -511,6 +511,10 @@
 	return certificates
 }
 
+func (a *AndroidApp) InstallApkName() string {
+	return a.installApkName
+}
+
 func (a *AndroidApp) generateAndroidBuildActions(ctx android.ModuleContext) {
 	var apkDeps android.Paths
 
@@ -1134,6 +1138,10 @@
 	a.generateAndroidBuildActions(ctx)
 }
 
+func (a *AndroidAppImport) InstallApkName() string {
+	return a.BaseModuleName()
+}
+
 func (a *AndroidAppImport) generateAndroidBuildActions(ctx android.ModuleContext) {
 	numCertPropsSet := 0
 	if String(a.properties.Certificate) != "" {
@@ -1191,6 +1199,8 @@
 		dexOutput = dexUncompressed
 	}
 
+	apkFilename := proptools.StringDefault(a.properties.Filename, a.BaseModuleName()+".apk")
+
 	// Sign or align the package
 	// TODO: Handle EXTERNAL
 	if !Bool(a.properties.Presigned) {
@@ -1201,11 +1211,11 @@
 			ctx.ModuleErrorf("Unexpected number of certificates were extracted: %q", certificates)
 		}
 		a.certificate = certificates[0]
-		signed := android.PathForModuleOut(ctx, "signed", ctx.ModuleName()+".apk")
+		signed := android.PathForModuleOut(ctx, "signed", apkFilename)
 		SignAppPackage(ctx, signed, dexOutput, certificates, nil)
 		a.outputFile = signed
 	} else {
-		alignedApk := android.PathForModuleOut(ctx, "zip-aligned", ctx.ModuleName()+".apk")
+		alignedApk := android.PathForModuleOut(ctx, "zip-aligned", apkFilename)
 		TransformZipAlign(ctx, alignedApk, dexOutput)
 		a.outputFile = alignedApk
 		a.certificate = presignedCertificate
@@ -1213,8 +1223,7 @@
 
 	// TODO: Optionally compress the output apk.
 
-	a.installPath = ctx.InstallFile(installDir,
-		proptools.StringDefault(a.properties.Filename, a.BaseModuleName()+".apk"), a.outputFile)
+	a.installPath = ctx.InstallFile(installDir, apkFilename, a.outputFile)
 
 	// TODO: androidmk converter jni libs
 }
diff --git a/java/builder.go b/java/builder.go
index 3a0247d..98f70cd 100644
--- a/java/builder.go
+++ b/java/builder.go
@@ -147,7 +147,12 @@
 
 	jarjar = pctx.AndroidStaticRule("jarjar",
 		blueprint.RuleParams{
-			Command:     "${config.JavaCmd} ${config.JavaVmFlags} -jar ${config.JarjarCmd} process $rulesFile $in $out",
+			Command: "${config.JavaCmd} ${config.JavaVmFlags}" +
+				// b/146418363 Enable Android specific jarjar transformer to drop compat annotations
+				// for newly repackaged classes. Dropping @UnsupportedAppUsage on repackaged classes
+				// avoids adding new hiddenapis after jarjar'ing.
+				" -DremoveAndroidCompatAnnotations=true" +
+				" -jar ${config.JarjarCmd} process $rulesFile $in $out",
 			CommandDeps: []string{"${config.JavaCmd}", "${config.JarjarCmd}", "$rulesFile"},
 		},
 		"rulesFile")
diff --git a/java/sdk_library.go b/java/sdk_library.go
index ff80d63..51e680b 100644
--- a/java/sdk_library.go
+++ b/java/sdk_library.go
@@ -394,13 +394,6 @@
 	}
 }
 
-// $(INTERNAL_PLATFORM_<apiTagName>_API_FILE) points to the generated
-// api file for the current source
-// TODO: remove this when apicheck is done in soong
-func (module *SdkLibrary) apiTagName(apiScope *apiScope) string {
-	return strings.Replace(strings.ToUpper(module.BaseModuleName()), ".", "_", -1) + apiScope.apiFileMakeVariableSuffix
-}
-
 func (module *SdkLibrary) latestApiFilegroupName(apiScope *apiScope) string {
 	return ":" + module.BaseModuleName() + ".api." + apiScope.name + ".latest"
 }
@@ -491,9 +484,6 @@
 		Libs                             []string
 		Arg_files                        []string
 		Args                             *string
-		Api_tag_name                     *string
-		Api_filename                     *string
-		Removed_api_filename             *string
 		Java_version                     *string
 		Merge_annotations_dirs           []string
 		Merge_inclusion_annotations_dirs []string
@@ -572,10 +562,6 @@
 	apiDir := module.getApiDir()
 	currentApiFileName = path.Join(apiDir, currentApiFileName)
 	removedApiFileName = path.Join(apiDir, removedApiFileName)
-	// TODO(jiyong): remove these three props
-	props.Api_tag_name = proptools.StringPtr(module.apiTagName(apiScope))
-	props.Api_filename = proptools.StringPtr(currentApiFileName)
-	props.Removed_api_filename = proptools.StringPtr(removedApiFileName)
 
 	// check against the not-yet-release API
 	props.Check_api.Current.Api_file = proptools.StringPtr(currentApiFileName)
diff --git a/sysprop/sysprop_library.go b/sysprop/sysprop_library.go
index a2e35d9..0932873 100644
--- a/sysprop/sysprop_library.go
+++ b/sysprop/sysprop_library.go
@@ -151,6 +151,12 @@
 
 	// Whether public stub exists or not.
 	Public_stub *bool `blueprint:"mutated"`
+
+	Cpp struct {
+		// Minimum sdk version that the artifact should support when it runs as part of mainline modules(APEX).
+		// Forwarded to cc_library.min_sdk_version
+		Min_sdk_version *string
+	}
 }
 
 var (
@@ -344,6 +350,7 @@
 	Vendor_available   *bool
 	Host_supported     *bool
 	Apex_available     []string
+	Min_sdk_version    *string
 }
 
 type javaLibraryProperties struct {
@@ -433,6 +440,7 @@
 	ccProps.Vendor_available = m.properties.Vendor_available
 	ccProps.Host_supported = m.properties.Host_supported
 	ccProps.Apex_available = m.ApexProperties.Apex_available
+	ccProps.Min_sdk_version = m.properties.Cpp.Min_sdk_version
 	ctx.CreateModule(cc.LibraryFactory, &ccProps)
 
 	scope := "internal"
diff --git a/ui/build/build.go b/ui/build/build.go
index f3feac2..1122733 100644
--- a/ui/build/build.go
+++ b/ui/build/build.go
@@ -53,7 +53,6 @@
 {{end -}}
 pool highmem_pool
  depth = {{.HighmemParallel}}
-build _kati_always_build_: phony
 {{if .HasKatiSuffix}}subninja {{.KatiBuildNinjaFile}}
 subninja {{.KatiPackageNinjaFile}}
 {{end -}}
diff --git a/ui/build/dumpvars.go b/ui/build/dumpvars.go
index a3234e3..a559330 100644
--- a/ui/build/dumpvars.go
+++ b/ui/build/dumpvars.go
@@ -229,8 +229,6 @@
 		"DEFAULT_ERROR_BUILD_MODULE_TYPES",
 		"BUILD_BROKEN_PREBUILT_ELF_FILES",
 		"BUILD_BROKEN_TREBLE_SYSPROP_NEVERALLOW",
-		"BUILD_BROKEN_USES_BUILD_AUX_EXECUTABLE",
-		"BUILD_BROKEN_USES_BUILD_AUX_STATIC_LIBRARY",
 		"BUILD_BROKEN_USES_BUILD_COPY_HEADERS",
 		"BUILD_BROKEN_USES_BUILD_EXECUTABLE",
 		"BUILD_BROKEN_USES_BUILD_FUZZ_TEST",
@@ -238,17 +236,12 @@
 		"BUILD_BROKEN_USES_BUILD_HOST_DALVIK_JAVA_LIBRARY",
 		"BUILD_BROKEN_USES_BUILD_HOST_DALVIK_STATIC_JAVA_LIBRARY",
 		"BUILD_BROKEN_USES_BUILD_HOST_EXECUTABLE",
-		"BUILD_BROKEN_USES_BUILD_HOST_FUZZ_TEST",
 		"BUILD_BROKEN_USES_BUILD_HOST_JAVA_LIBRARY",
-		"BUILD_BROKEN_USES_BUILD_HOST_NATIVE_TEST",
 		"BUILD_BROKEN_USES_BUILD_HOST_PREBUILT",
 		"BUILD_BROKEN_USES_BUILD_HOST_SHARED_LIBRARY",
 		"BUILD_BROKEN_USES_BUILD_HOST_STATIC_LIBRARY",
-		"BUILD_BROKEN_USES_BUILD_HOST_STATIC_TEST_LIBRARY",
-		"BUILD_BROKEN_USES_BUILD_HOST_TEST_CONFIG",
 		"BUILD_BROKEN_USES_BUILD_JAVA_LIBRARY",
 		"BUILD_BROKEN_USES_BUILD_MULTI_PREBUILT",
-		"BUILD_BROKEN_USES_BUILD_NATIVE_BENCHMARK",
 		"BUILD_BROKEN_USES_BUILD_NATIVE_TEST",
 		"BUILD_BROKEN_USES_BUILD_NOTICE_FILE",
 		"BUILD_BROKEN_USES_BUILD_PACKAGE",
@@ -258,8 +251,6 @@
 		"BUILD_BROKEN_USES_BUILD_SHARED_LIBRARY",
 		"BUILD_BROKEN_USES_BUILD_STATIC_JAVA_LIBRARY",
 		"BUILD_BROKEN_USES_BUILD_STATIC_LIBRARY",
-		"BUILD_BROKEN_USES_BUILD_STATIC_TEST_LIBRARY",
-		"BUILD_BROKEN_USES_BUILD_TARGET_TEST_CONFIG",
 	}, exportEnvVars...), BannerVars...)
 
 	make_vars, err := dumpMakeVars(ctx, config, config.Arguments(), allVars, true)
diff --git a/ui/build/exec.go b/ui/build/exec.go
index e435c53..053bbae 100644
--- a/ui/build/exec.go
+++ b/ui/build/exec.go
@@ -19,6 +19,8 @@
 	"io"
 	"os/exec"
 	"strings"
+	"syscall"
+	"time"
 )
 
 // Cmd is a wrapper of os/exec.Cmd that integrates with the build context for
@@ -33,6 +35,8 @@
 	ctx    Context
 	config Config
 	name   string
+
+	started time.Time
 }
 
 func Command(ctx Context, config Config, name string, executable string, args ...string) *Cmd {
@@ -57,7 +61,20 @@
 		c.wrapSandbox()
 	}
 
-	c.ctx.Verboseln(c.Path, c.Args)
+	c.ctx.Verbosef("%q executing %q %v\n", c.name, c.Path, c.Args)
+	c.started = time.Now()
+}
+
+func (c *Cmd) report() {
+	if c.Cmd.ProcessState != nil {
+		rusage := c.Cmd.ProcessState.SysUsage().(*syscall.Rusage)
+		c.ctx.Verbosef("%q finished with exit code %d (%s real, %s user, %s system, %dMB maxrss)",
+			c.name, c.Cmd.ProcessState.ExitCode(),
+			time.Since(c.started).Round(time.Millisecond),
+			c.Cmd.ProcessState.UserTime().Round(time.Millisecond),
+			c.Cmd.ProcessState.SystemTime().Round(time.Millisecond),
+			rusage.Maxrss/1024)
+	}
 }
 
 func (c *Cmd) Start() error {
@@ -68,21 +85,30 @@
 func (c *Cmd) Run() error {
 	c.prepare()
 	err := c.Cmd.Run()
+	c.report()
 	return err
 }
 
 func (c *Cmd) Output() ([]byte, error) {
 	c.prepare()
 	bytes, err := c.Cmd.Output()
+	c.report()
 	return bytes, err
 }
 
 func (c *Cmd) CombinedOutput() ([]byte, error) {
 	c.prepare()
 	bytes, err := c.Cmd.CombinedOutput()
+	c.report()
 	return bytes, err
 }
 
+func (c *Cmd) Wait() error {
+	err := c.Cmd.Wait()
+	c.report()
+	return err
+}
+
 // StartOrFatal is equivalent to Start, but handles the error with a call to ctx.Fatal
 func (c *Cmd) StartOrFatal() {
 	if err := c.Start(); err != nil {
diff --git a/ui/build/kati.go b/ui/build/kati.go
index 8796a4f..2eb7850 100644
--- a/ui/build/kati.go
+++ b/ui/build/kati.go
@@ -67,6 +67,7 @@
 		"--ninja_dir=" + config.OutDir(),
 		"--ninja_suffix=" + config.KatiSuffix() + extraSuffix,
 		"--no_ninja_prelude",
+		"--use_ninja_phony_output",
 		"--regen",
 		"--ignore_optional_include=" + filepath.Join(config.OutDir(), "%.P"),
 		"--detect_android_echo",
diff --git a/ui/build/ninja.go b/ui/build/ninja.go
index dfc3be1..1b13e5d 100644
--- a/ui/build/ninja.go
+++ b/ui/build/ninja.go
@@ -58,6 +58,7 @@
 	args = append(args, "-f", config.CombinedNinjaFile())
 
 	args = append(args,
+		"-o", "usesphonyoutputs=yes",
 		"-w", "dupbuild=err",
 		"-w", "missingdepfile=err")
 
diff --git a/ui/build/soong.go b/ui/build/soong.go
index 9b8d648..2fbf381 100644
--- a/ui/build/soong.go
+++ b/ui/build/soong.go
@@ -119,7 +119,11 @@
 		cmd := Command(ctx, config, "soong "+name,
 			config.PrebuiltBuildTool("ninja"),
 			"-d", "keepdepfile",
+			"-o", "usesphonyoutputs=yes",
+			"-o", "preremoveoutputs=yes",
 			"-w", "dupbuild=err",
+			"-w", "outputdir=err",
+			"-w", "missingoutfile=err",
 			"-j", strconv.Itoa(config.Parallel()),
 			"--frontend_file", fifo,
 			"-f", filepath.Join(config.SoongOutDir(), file))
diff --git a/ui/build/test_build.go b/ui/build/test_build.go
index 5109465..4ff9483 100644
--- a/ui/build/test_build.go
+++ b/ui/build/test_build.go
@@ -50,10 +50,10 @@
 	// Get a list of leaf nodes in the dependency graph from ninja
 	executable := config.PrebuiltBuildTool("ninja")
 
-	args := []string{}
-	args = append(args, config.NinjaArgs()...)
-	args = append(args, "-f", config.CombinedNinjaFile())
-	args = append(args, "-t", "targets", "rule")
+	common_args := []string{}
+	common_args = append(common_args, config.NinjaArgs()...)
+	common_args = append(common_args, "-f", config.CombinedNinjaFile())
+	args := append(common_args, "-t", "targets", "rule")
 
 	cmd := Command(ctx, config, "ninja", executable, args...)
 	stdout, err := cmd.StdoutPipe()
@@ -96,9 +96,31 @@
 		sb := &strings.Builder{}
 		title := "Dependencies in out found with no rule to create them:"
 		fmt.Fprintln(sb, title)
-		for _, dep := range danglingRulesList {
-			fmt.Fprintln(sb, "  ", dep)
+
+		report_lines := 1
+		for i, dep := range danglingRulesList {
+			if report_lines > 20 {
+				fmt.Fprintf(sb, "  ... and %d more\n", len(danglingRulesList)-i)
+				break
+			}
+			// It's helpful to see the reverse dependencies. ninja -t query is the
+			// best tool we got for that. Its output starts with the dependency
+			// itself.
+			query_cmd := Command(ctx, config, "ninja", executable,
+				append(common_args, "-t", "query", dep)...)
+			query_stdout, err := query_cmd.StdoutPipe()
+			if err != nil {
+				ctx.Fatal(err)
+			}
+			query_cmd.StartOrFatal()
+			scanner := bufio.NewScanner(query_stdout)
+			for scanner.Scan() {
+				report_lines++
+				fmt.Fprintln(sb, " ", scanner.Text())
+			}
+			query_cmd.WaitOrFatal()
 		}
+
 		ts.FinishAction(status.ActionResult{
 			Action: action,
 			Error:  fmt.Errorf(title),