Convert libprotobuf to Bazel (9b84678f) · Commits · e / os / android_build_soong

android/allowlists/allowlists.go

+1 −0

Original line number	Diff line number	Diff line
		@@ -513,6 +513,7 @@ var (
		"libprotobuf_support",
		"libtinytemplate",
		"libserde_json",
		"libprotobuf",

		// ext
		"tagsoup",

bp2build/rust_library_conversion_test.go

+30 −0

Original line number	Diff line number	Diff line
		@@ -16,6 +16,36 @@ func registerRustLibraryModuleTypes(ctx android.RegistrationContext) {
		ctx.RegisterModuleType("rust_library_host", rust.RustLibraryHostFactory)
		}

		func TestLibProtobuf(t *testing.T) {
		runRustLibraryTestCase(t, Bp2buildTestCase{
		Dir: "external/rust/crates/foo",
		Blueprint: "",
		Filesystem: map[string]string{
		"external/rust/crates/foo/src/lib.rs": "",
		"external/rust/crates/foo/Android.bp": `
		rust_library_host {
		name: "libprotobuf",
		crate_name: "protobuf",
		srcs: ["src/lib.rs"],
		bazel_module: { bp2build_available: true },
		}
		`,
		},
		ExpectedBazelTargets: []string{
		// TODO(b/290790800): Remove the restriction when rust toolchain for android is implemented
		makeBazelTargetHostOrDevice("rust_library", "libprotobuf", AttrNameToString{
		"crate_name": `"protobuf"`,
		"srcs": `["src/lib.rs"]`,
		"deps": `[":libprotobuf_build_script"]`,
		}, android.HostSupported),
		makeBazelTargetHostOrDevice("cargo_build_script", "libprotobuf_build_script", AttrNameToString{
		"srcs": `["build.rs"]`,
		}, android.HostSupported),
		},
		},
		)
		}

		func TestRustLibrary(t *testing.T) {
		expectedAttrs := AttrNameToString{
		"crate_name": `"foo"`,

rust/library.go

+80 −0

Original line number	Diff line number	Diff line
		@@ -812,11 +812,21 @@ type rustLibraryAttributes struct {

		func libraryBp2build(ctx android.TopDownMutatorContext, m *Module) {
		lib := m.compiler.(*libraryDecorator)

		srcs, compileData := srcsAndCompileDataAttrs(ctx, *lib.baseCompiler)

		deps := android.BazelLabelForModuleDeps(ctx, append(
		lib.baseCompiler.Properties.Rustlibs,
		lib.baseCompiler.Properties.Rlibs...,
		))

		cargoBuildScript := cargoBuildScriptBp2build(ctx, m)
		if cargoBuildScript != nil {
		deps.Add(&bazel.Label{
		Label: ":" + *cargoBuildScript,
		})
		}

		procMacroDeps := android.BazelLabelForModuleDeps(ctx, lib.baseCompiler.Properties.Proc_macros)

		var rustcFLags []string
		@@ -870,3 +880,73 @@ func libraryBp2build(ctx android.TopDownMutatorContext, m *Module) {
		restriction,
		)
		}

		type cargoBuildScriptAttributes struct {
		Srcs bazel.LabelListAttribute
		Edition bazel.StringAttribute
		Version bazel.StringAttribute
		}

		func cargoBuildScriptBp2build(ctx android.TopDownMutatorContext, m Module) string {
		// Soong treats some crates like libprotobuf as special in that they have
		// cargo build script ran to produce an out folder and check it into AOSP
		// For example, https://cs.android.com/android/platform/superproject/main/+/main:external/rust/crates/protobuf/out/
		// is produced by cargo build script https://cs.android.com/android/platform/superproject/main/+/main:external/rust/crates/protobuf/build.rs
		// The out folder is then fed into `rust_library` by a genrule
		// https://cs.android.com/android/platform/superproject/main/+/main:external/rust/crates/protobuf/Android.bp;l=22
		// This allows Soong to decouple from cargo completely.

		// Soong decouples from cargo so that it has control over cc compilation.
		// https://cs.android.com/android/platform/superproject/main/+/main:development/scripts/cargo2android.py;l=1033-1041;drc=8449944a50a0445a5ecaf9b7aed12608c81bf3f1
		// generates a `cc_library_static` module to have custom cc flags.
		// Since bp2build will convert the cc modules to cc targets which include the cflags,
		// Bazel does not need to have this optimization.

		// Performance-wise: rust_library -> cargo_build_script vs rust_library -> genrule (like Soong)
		// don't have any major difference in build time in Bazel. So using cargo_build_script does not slow
		// down the build.

		// The benefit of using `cargo_build_script` here is that it would take care of setting correct
		// `OUT_DIR` for us - similar to what Soong does here
		// https://cs.android.com/android/platform/superproject/main/+/main:build/soong/rust/builder.go;l=202-218;drc=f29ca58e88c5846bbe8955e5192135e5ab4f14a1

		// TODO(b/297364081): cargo2android.py has logic for when generate/not cc_library_static and out directory
		// bp2build might be able use the same logic for when to use `cargo_build_script`.
		// For now, we're building libprotobuf_build_script as a one-off until we have a more principled solution
		if m.Name() != "libprotobuf" {
		return nil
		}

		lib := m.compiler.(*libraryDecorator)

		name := m.Name() + "_build_script"
		attrs := &cargoBuildScriptAttributes{
		Srcs: bazel.MakeLabelListAttribute(
		android.BazelLabelForModuleSrc(ctx, []string{"build.rs"}),
		),
		Edition: bazel.StringAttribute{
		Value: lib.baseCompiler.Properties.Edition,
		},
		Version: bazel.StringAttribute{
		Value: lib.baseCompiler.Properties.Cargo_pkg_version,
		},
		}

		// TODO(b/290790800): Remove the restriction when rust toolchain for android is implemented
		var restriction bazel.BoolAttribute
		restriction.SetSelectValue(bazel.OsConfigurationAxis, "android", proptools.BoolPtr(false))

		ctx.CreateBazelTargetModuleWithRestrictions(
		bazel.BazelTargetModuleProperties{
		Rule_class: "cargo_build_script",
		Bzl_load_location: "@rules_rust//cargo:cargo_build_script.bzl",
		},
		android.CommonAttributes{
		Name: name,
		},
		attrs,
		restriction,
		)

		return &name
		}