Merge "Read BUILD files in bp2build" am: 01f8784246

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2617569

Change-Id: I890438dbb170523db0b6379e2c2f27e9b83e7f4c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

android/allowlists/allowlists.go

@@ -461,6 +461,9 @@ var (
 
 		// TODO(b/266459895): remove this and the placeholder BUILD file after re-enabling libunwindstack
 		"external/rust/crates/rustc-demangle-capi":/* recursive = */ false,
+
+		// Used for testing purposes only. Should not actually exist in the real source tree.
+		"testpkg/keep_build_file":/* recursive = */ false,
 	}
 
 	Bp2buildModuleAlwaysConvertList = []string{
@@ -845,9 +848,6 @@ var (
 		"libbase_ndk",  // TODO(b/186826477): fails to link libctscamera2_jni for device (required for CtsCameraTestCases)
 		"bouncycastle", // TODO(b/274474005): Need support for custom system_modules.
 
-		// python protos
-		"libprotobuf-python", // Has a handcrafted alternative
-
 		// genrule incompatibilities
 		"brotli-fuzzer-corpus",                                       // TODO(b/202015218): outputs are in location incompatible with bazel genrule handling.
 		"platform_tools_properties", "build_tools_source_properties", // TODO(b/203369847): multiple genrules in the same package creating the same file

android/bazel.go

@@ -537,6 +537,12 @@ func registerBp2buildConversionMutator(ctx RegisterMutatorsContext) {
 }
 
 func convertWithBp2build(ctx TopDownMutatorContext) {
+	if ctx.Config().HasBazelBuildTargetInSource(ctx) {
+		// Defer to the BUILD target. Generating an additional target would
+		// cause a BUILD file conflict.
+		return
+	}
+
 	bModule, ok := ctx.Module().(Bazelable)
 	if !ok || !bModule.shouldConvertWithBp2build(ctx, ctx.Module()) {
 		return

android/config.go

@@ -291,6 +291,10 @@ type config struct {
 	// "--bazel-force-enabled-modules"
 	bazelForceEnabledModules map[string]struct{}
 
+	// Names of Bazel targets as defined by BUILD files in the source tree,
+	// keyed by the directory in which they are defined.
+	bazelTargetsByDir map[string][]string
+
 	// If true, for any requests to Bazel, communicate with a Bazel proxy using
 	// unix sockets, instead of spawning Bazel as a subprocess.
 	UseBazelProxy bool
@@ -2002,6 +2006,20 @@ func (c *config) LogMixedBuild(ctx BaseModuleContext, useBazel bool) {
 	}
 }
 
+func (c *config) HasBazelBuildTargetInSource(ctx BaseModuleContext) bool {
+	moduleName := ctx.Module().Name()
+	for _, buildTarget := range c.bazelTargetsByDir[ctx.ModuleDir()] {
+		if moduleName == buildTarget {
+			return true
+		}
+	}
+	return false
+}
+
+func (c *config) SetBazelBuildFileTargets(bazelTargetsByDir map[string][]string) {
+	c.bazelTargetsByDir = bazelTargetsByDir
+}
+
 // ApiSurfaces directory returns the source path inside the api_surfaces repo
 // (relative to workspace root).
 func (c *config) ApiSurfacesDir(s ApiSurface, version string) string {

cmd/soong_build/main.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"time"
 
@@ -762,6 +763,43 @@ func excludedFromSymlinkForest(ctx *android.Context, verbose bool) []string {
 	return excluded
 }
 
+// buildTargetsByPackage parses Bazel BUILD.bazel and BUILD files under
+// the workspace, and returns a map containing names of Bazel targets defined in
+// these BUILD files.
+// For example, maps "//foo/bar" to ["baz", "qux"] if `//foo/bar:{baz,qux}` exist.
+func buildTargetsByPackage(ctx *android.Context) map[string][]string {
+	existingBazelFiles, err := getExistingBazelRelatedFiles(topDir)
+	maybeQuit(err, "Error determining existing Bazel-related files")
+
+	result := map[string][]string{}
+
+	// Search for instances of `name = "$NAME"` (with arbitrary spacing).
+	targetNameRegex := regexp.MustCompile(`(?m)^\s*name\s*=\s*\"([^\"]+)\"`)
+
+	for _, path := range existingBazelFiles {
+		if !ctx.Config().Bp2buildPackageConfig.ShouldKeepExistingBuildFileForDir(filepath.Dir(path)) {
+			continue
+		}
+		fullPath := shared.JoinPath(topDir, path)
+		sourceDir := filepath.Dir(path)
+		fileInfo, err := os.Stat(fullPath)
+		maybeQuit(err, "Error accessing Bazel file '%s'", fullPath)
+
+		if !fileInfo.IsDir() &&
+			(fileInfo.Name() == "BUILD" || fileInfo.Name() == "BUILD.bazel") {
+			// Process this BUILD file.
+			buildFileContent, err := os.ReadFile(fullPath)
+			maybeQuit(err, "Error reading Bazel file '%s'", fullPath)
+
+			matches := targetNameRegex.FindAllStringSubmatch(string(buildFileContent), -1)
+			for _, match := range matches {
+				result[sourceDir] = append(result[sourceDir], match[1])
+			}
+		}
+	}
+	return result
+}
+
 // Run Soong in the bp2build mode. This creates a standalone context that registers
 // an alternate pipeline of mutators and singletons specifically for generating
 // Bazel BUILD files instead of Ninja files.
@@ -769,6 +807,10 @@ func runBp2Build(ctx *android.Context, extraNinjaDeps []string, metricsDir strin
 	var codegenMetrics *bp2build.CodegenMetrics
 	ctx.EventHandler.Do("bp2build", func() {
 
+		ctx.EventHandler.Do("read_build", func() {
+			ctx.Config().SetBazelBuildFileTargets(buildTargetsByPackage(ctx))
+		})
+
 		// Propagate "allow misssing dependencies" bit. This is normally set in
 		// newContext(), but we create ctx without calling that method.
 		ctx.SetAllowMissingDependencies(ctx.Config().AllowMissingDependencies())

tests/bp2build_bazel_test.sh

@@ -232,6 +232,63 @@ function test_bp2build_generates_all_buildfiles {
   eval "${_save_trap}"
 }
 
+function test_build_files_take_precedence {
+  _save_trap=$(trap -p EXIT)
+  trap '[[ $? -ne 0 ]] && echo Are you running this locally? Try changing --sandbox_tmpfs_path to something other than /tmp/ in build/bazel/linux.bazelrc.' EXIT
+  _build_files_take_precedence
+  eval "${_save_trap}"
+}
+
+function _build_files_take_precedence {
+  setup
+
+  # This specific directory is hardcoded in bp2build as being one
+  # where the BUILD file should be intentionally kept.
+  mkdir -p testpkg/keep_build_file
+  cat > testpkg/keep_build_file/Android.bp <<'EOF'
+genrule {
+    name: "print_origin",
+    cmd: "echo 'from_soong' > $(out)",
+    out: [
+        "origin.txt",
+    ],
+    bazel_module: {
+        bp2build_available: true,
+    },
+  }
+EOF
+
+  run_soong bp2build
+  run_bazel build --config=android --config=bp2build --config=ci //testpkg/keep_build_file:print_origin
+
+  local -r output_file="$(find -L bazel-out -name origin.txt)"
+  if [[ ! -f "${output_file}" ]]; then
+    fail "Expected origin.txt to be generated, but was missing"
+  fi
+  if ! grep from_soong "${output_file}"; then
+    fail "Expected to find 'from_soong' in '${output_file}'"
+  fi
+
+  cat > testpkg/keep_build_file/BUILD.bazel <<'EOF'
+genrule(
+    name = "print_origin",
+    outs = ["origin.txt"],
+    cmd = "echo 'from_bazel' > $@",
+)
+EOF
+
+  # Clean the workspace. There is a test infrastructure bug where run_bazel
+  # will symlink Android.bp files in the source directory again and thus
+  # pollute the workspace.
+  # TODO: b/286059878 - Remove this clean after the underlying bug is fixed.
+  run_soong clean
+  run_soong bp2build
+  run_bazel build --config=android --config=bp2build --config=ci //testpkg/keep_build_file:print_origin
+  if ! grep from_bazel "${output_file}"; then
+    fail "Expected to find 'from_bazel' in '${output_file}'"
+  fi
+}
+
 function test_bp2build_symlinks_files {
   setup
   mkdir -p foo