Add a soong-only mode to soong-ui

The previous --skip-kati flag could be interpreted as "do not run kati
to re-generate ninja file". Add a more specific flag for the "soong
only" build use-case, where we do not load the kati-generated ninja
files at all.

Bug: 189187214
Test: build/soong/soong_ui.bash \
  --make-mode \
  --soong-only
  --skip-soong-tests \
  TARGET_PRODUCT=mainline_sdk \
  SOONG_ALLOW_MISSING_DEPENDENCIES=true \
  SOONG_SDK_SNAPSHOT_VERSION=unversioned \
  SOONG_SDK_SNAPSHOT_USE_SRCJAR=true \
  out/soong/mainline-sdks/art-module-sdk.zip
Change-Id: I91abbd28af517d4b550ebc6d88fd64947caf9545

ui/build/build.go

@@ -60,15 +60,15 @@ builddir = {{.OutDir}}
 {{end -}}
 pool highmem_pool
  depth = {{.HighmemParallel}}
-{{if .HasKatiSuffix}}subninja {{.KatiBuildNinjaFile}}
+{{if and (not .SkipKatiNinja) .HasKatiSuffix}}subninja {{.KatiBuildNinjaFile}}
 subninja {{.KatiPackageNinjaFile}}
 {{end -}}
 subninja {{.SoongNinjaFile}}
 `))
 
 func createCombinedBuildNinjaFile(ctx Context, config Config) {
-	// If we're in SkipKati mode, skip creating this file if it already exists
+	// If we're in SkipKati mode but want to run kati ninja, skip creating this file if it already exists
-	if config.SkipKati() {
+	if config.SkipKati() && !config.SkipKatiNinja() {
 		if _, err := os.Stat(config.CombinedNinjaFile()); err == nil || !os.IsNotExist(err) {
 			return
 		}
@@ -94,13 +94,15 @@ const (
 	RunSoong = 1 << iota
 	// Whether to run kati to generate a ninja file.
 	RunKati = 1 << iota
+	// Whether to include the kati-generated ninja file in the combined ninja.
+	RunKatiNinja = 1 << iota
 	// Whether to run ninja on the combined ninja.
 	RunNinja = 1 << iota
 	// Whether to run bazel on the combined ninja.
 	RunBazel        = 1 << iota
 	RunBuildTests   = 1 << iota
-	RunAll          = RunProductConfig | RunSoong | RunKati | RunNinja
+	RunAll          = RunProductConfig | RunSoong | RunKati | RunKatiNinja | RunNinja
-	RunAllWithBazel = RunProductConfig | RunSoong | RunKati | RunBazel
+	RunAllWithBazel = RunProductConfig | RunSoong | RunKati | RunKatiNinja | RunBazel
 )
 
 // checkProblematicFiles fails the build if existing Android.mk or CleanSpec.mk files are found at the root of the tree.
@@ -228,6 +230,10 @@ func Build(ctx Context, config Config) {
 		ctx.Verboseln("Skipping Kati as requested")
 		what = what &^ RunKati
 	}
+	if config.SkipKatiNinja() {
+		ctx.Verboseln("Skipping use of Kati ninja as requested")
+		what = what &^ RunKatiNinja
+	}
 	if config.SkipNinja() {
 		ctx.Verboseln("Skipping Ninja as requested")
 		what = what &^ RunNinja
@@ -277,7 +283,7 @@ func Build(ctx Context, config Config) {
 		runKatiPackage(ctx, config)
 
 		ioutil.WriteFile(config.LastKatiSuffixFile(), []byte(config.KatiSuffix()), 0666) // a+rw
-	} else {
+	} else if what&RunKatiNinja != 0 {
 		// Load last Kati Suffix if it exists
 		if katiSuffix, err := ioutil.ReadFile(config.LastKatiSuffixFile()); err == nil {
 			ctx.Verboseln("Loaded previous kati config:", string(katiSuffix))

ui/build/config.go

@@ -48,6 +48,7 @@ type configImpl struct {
 	dist           bool
 	skipConfig     bool
 	skipKati       bool
+	skipKatiNinja  bool
 	skipNinja      bool
 	skipSoongTests bool
 
@@ -573,7 +574,11 @@ func (c *configImpl) parseArgs(ctx Context, args []string) {
 			c.skipConfig = true
 			c.skipKati = true
 		} else if arg == "--skip-kati" {
+			// TODO: remove --skip-kati once module builds have been migrated to --song-only
 			c.skipKati = true
+		} else if arg == "--soong-only" {
+			c.skipKati = true
+			c.skipKatiNinja = true
 		} else if arg == "--skip-soong-tests" {
 			c.skipSoongTests = true
 		} else if len(arg) > 0 && arg[0] == '-' {
@@ -789,6 +794,10 @@ func (c *configImpl) SkipKati() bool {
 	return c.skipKati
 }
 
+func (c *configImpl) SkipKatiNinja() bool {
+	return c.skipKatiNinja
+}
+
 func (c *configImpl) SkipNinja() bool {
 	return c.skipNinja
 }