bp2build/build_conversion.go - android_build_soong - Gitiles

 // Copyright 2020 Google Inc. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 package bp2build

 /*
 For shareable/common functionality for conversion from soong-module to build files
 for queryview/bp2build
 */

 import (
 	"fmt"
 	"reflect"
 	"sort"
 	"strings"

 	"android/soong/android"
 	"android/soong/bazel"
 	"android/soong/starlark_fmt"
 	"github.com/google/blueprint"
 	"github.com/google/blueprint/proptools"
 )

 type BazelAttributes struct {
 	Attrs map[string]string
 }

 type BazelLoadSymbol struct {
 	// The name of the symbol in the file being loaded
 	symbol string
 	// The name the symbol wil have in this file. Can be left blank to use the same name as symbol.
 	alias string
 }

 type BazelLoad struct {
 	file    string
 	symbols []BazelLoadSymbol
 }

 type BazelTarget struct {
 	name        string
 	packageName string
 	content     string
 	ruleClass   string
 	loads       []BazelLoad
 }

 // Label is the fully qualified Bazel label constructed from the BazelTarget's
 // package name and target name.
 func (t BazelTarget) Label() string {
 	if t.packageName == "." {
 		return "//:" + t.name
 	} else {
 		return "//" + t.packageName + ":" + t.name
 	}
 }

 // PackageName returns the package of the Bazel target.
 // Defaults to root of tree.
 func (t BazelTarget) PackageName() string {
 	if t.packageName == "" {
 		return "."
 	}
 	return t.packageName
 }

 // BazelTargets is a typedef for a slice of BazelTarget objects.
 type BazelTargets []BazelTarget

 func (targets BazelTargets) packageRule() *BazelTarget {
 	for _, target := range targets {
 		if target.ruleClass == "package" {
 			return &target
 		}
 	}
 	return nil
 }

 // sort a list of BazelTargets in-place, by name, and by generated/handcrafted types.
 func (targets BazelTargets) sort() {
 	sort.Slice(targets, func(i, j int) bool {
 		return targets[i].name < targets[j].name
 	})
 }

 // String returns the string representation of BazelTargets, without load
 // statements (use LoadStatements for that), since the targets are usually not
 // adjacent to the load statements at the top of the BUILD file.
 func (targets BazelTargets) String() string {
 	var res strings.Builder
 	for i, target := range targets {
 		if target.ruleClass != "package" {
 			res.WriteString(target.content)
 		}
 		if i != len(targets)-1 {
 			res.WriteString("\n\n")
 		}
 	}
 	return res.String()
 }

 // LoadStatements return the string representation of the sorted and deduplicated
 // Starlark rule load statements needed by a group of BazelTargets.
 func (targets BazelTargets) LoadStatements() string {
 	// First, merge all the load statements from all the targets onto one list
 	bzlToLoadedSymbols := map[string][]BazelLoadSymbol{}
 	for _, target := range targets {
 		for _, load := range target.loads {
 		outer:
 			for _, symbol := range load.symbols {
 				alias := symbol.alias
 				if alias == "" {
 					alias = symbol.symbol
 				}
 				for _, otherSymbol := range bzlToLoadedSymbols[load.file] {
 					otherAlias := otherSymbol.alias
 					if otherAlias == "" {
 						otherAlias = otherSymbol.symbol
 					}
 					if symbol.symbol == otherSymbol.symbol && alias == otherAlias {
 						continue outer
 					} else if alias == otherAlias {
 						panic(fmt.Sprintf("Conflicting destination (%s) for loads of %s and %s", alias, symbol.symbol, otherSymbol.symbol))
 					}
 				}
 				bzlToLoadedSymbols[load.file] = append(bzlToLoadedSymbols[load.file], symbol)
 			}
 		}
 	}

 	var loadStatements strings.Builder
 	for i, bzl := range android.SortedKeys(bzlToLoadedSymbols) {
 		symbols := bzlToLoadedSymbols[bzl]
 		loadStatements.WriteString("load(\"")
 		loadStatements.WriteString(bzl)
 		loadStatements.WriteString("\", ")
 		sort.Slice(symbols, func(i, j int) bool {
 			if symbols[i].symbol < symbols[j].symbol {
 				return true
 			}
 			return symbols[i].alias < symbols[j].alias
 		})
 		for j, symbol := range symbols {
 			if symbol.alias != "" && symbol.alias != symbol.symbol {
 				loadStatements.WriteString(symbol.alias)
 				loadStatements.WriteString(" = ")
 			}
 			loadStatements.WriteString("\"")
 			loadStatements.WriteString(symbol.symbol)
 			loadStatements.WriteString("\"")
 			if j != len(symbols)-1 {
 				loadStatements.WriteString(", ")
 			}
 		}
 		loadStatements.WriteString(")")
 		if i != len(bzlToLoadedSymbols)-1 {
 			loadStatements.WriteString("\n")
 		}
 	}
 	return loadStatements.String()
 }

 type bpToBuildContext interface {
 	ModuleName(module blueprint.Module) string
 	ModuleDir(module blueprint.Module) string
 	ModuleSubDir(module blueprint.Module) string
 	ModuleType(module blueprint.Module) string

 	VisitAllModules(visit func(blueprint.Module))
 	VisitDirectDeps(module blueprint.Module, visit func(blueprint.Module))
 }

 type CodegenContext struct {
 	config             android.Config
 	context            *android.Context
 	mode               CodegenMode
 	additionalDeps     []string
 	unconvertedDepMode unconvertedDepsMode
 	topDir             string
 }

 func (ctx *CodegenContext) Mode() CodegenMode {
 	return ctx.mode
 }

 // CodegenMode is an enum to differentiate code-generation modes.
 type CodegenMode int

 const (
 	// QueryView - generate BUILD files with targets representing fully mutated
 	// Soong modules, representing the fully configured Soong module graph with
 	// variants and dependency edges.
 	//
 	// This mode is used for discovering and introspecting the existing Soong
 	// module graph.
 	QueryView CodegenMode = iota
 )

 type unconvertedDepsMode int

 const (
 	// Include a warning in conversion metrics about converted modules with unconverted direct deps
 	warnUnconvertedDeps unconvertedDepsMode = iota
 	// Error and fail conversion if encountering a module with unconverted direct deps
 	// Enabled by setting environment variable `BP2BUILD_ERROR_UNCONVERTED`
 	errorModulesUnconvertedDeps
 )

 func (mode CodegenMode) String() string {
 	switch mode {
 	case QueryView:
 		return "QueryView"
 	default:
 		return fmt.Sprintf("%d", mode)
 	}
 }

 // AddNinjaFileDeps adds dependencies on the specified files to be added to the ninja manifest. The
 // primary builder will be rerun whenever the specified files are modified. Allows us to fulfill the
 // PathContext interface in order to add dependencies on hand-crafted BUILD files. Note: must also
 // call AdditionalNinjaDeps and add them manually to the ninja file.
 func (ctx *CodegenContext) AddNinjaFileDeps(deps ...string) {
 	ctx.additionalDeps = append(ctx.additionalDeps, deps...)
 }

 // AdditionalNinjaDeps returns additional ninja deps added by CodegenContext
 func (ctx *CodegenContext) AdditionalNinjaDeps() []string {
 	return ctx.additionalDeps
 }

 func (ctx *CodegenContext) Config() android.Config    { return ctx.config }
 func (ctx *CodegenContext) Context() *android.Context { return ctx.context }

 // NewCodegenContext creates a wrapper context that conforms to PathContext for
 // writing BUILD files in the output directory.
 func NewCodegenContext(config android.Config, context *android.Context, mode CodegenMode, topDir string) *CodegenContext {
 	var unconvertedDeps unconvertedDepsMode
 	return &CodegenContext{
 		context:            context,
 		config:             config,
 		mode:               mode,
 		unconvertedDepMode: unconvertedDeps,
 		topDir:             topDir,
 	}
 }

 // props is an unsorted map. This function ensures that
 // the generated attributes are sorted to ensure determinism.
 func propsToAttributes(props map[string]string) string {
 	var attributes string
 	for _, propName := range android.SortedKeys(props) {
 		attributes += fmt.Sprintf("    %s = %s,\n", propName, props[propName])
 	}
 	return attributes
 }

 type conversionResults struct {
 	buildFileToTargets    map[string]BazelTargets
 	moduleNameToPartition map[string]string
 }

 func (r conversionResults) BuildDirToTargets() map[string]BazelTargets {
 	return r.buildFileToTargets
 }

 func GenerateBazelTargets(ctx *CodegenContext, generateFilegroups bool) (conversionResults, []error) {
 	ctx.Context().BeginEvent("GenerateBazelTargets")
 	defer ctx.Context().EndEvent("GenerateBazelTargets")
 	buildFileToTargets := make(map[string]BazelTargets)

 	dirs := make(map[string]bool)
 	moduleNameToPartition := make(map[string]string)

 	var errs []error

 	bpCtx := ctx.Context()
 	bpCtx.VisitAllModules(func(m blueprint.Module) {
 		dir := bpCtx.ModuleDir(m)
 		dirs[dir] = true

 		var targets []BazelTarget

 		switch ctx.Mode() {
 		case QueryView:
 			// Blocklist certain module types from being generated.
 			if canonicalizeModuleType(bpCtx.ModuleType(m)) == "package" {
 				// package module name contain slashes, and thus cannot
 				// be mapped cleanly to a bazel label.
 				return
 			}
 			t, err := generateSoongModuleTarget(bpCtx, m)
 			if err != nil {
 				errs = append(errs, err)
 			}
 			targets = append(targets, t)
 		default:
 			errs = append(errs, fmt.Errorf("Unknown code-generation mode: %s", ctx.Mode()))
 			return
 		}

 		for _, target := range targets {
 			targetDir := target.PackageName()
 			buildFileToTargets[targetDir] = append(buildFileToTargets[targetDir], target)
 		}
 	})

 	if len(errs) > 0 {
 		return conversionResults{}, errs
 	}

 	if generateFilegroups {
 		// Add a filegroup target that exposes all sources in the subtree of this package
 		// NOTE: This also means we generate a BUILD file for every Android.bp file (as long as it has at least one module)
 		//
 		// This works because: https://bazel.build/reference/be/functions#exports_files
 		// "As a legacy behaviour, also files mentioned as input to a rule are exported with the
 		// default visibility until the flag --incompatible_no_implicit_file_export is flipped. However, this behavior
 		// should not be relied upon and actively migrated away from."
 		//
 		// TODO(b/198619163): We should change this to export_files(glob(["**/*"])) instead, but doing that causes these errors:
 		// "Error in exports_files: generated label '//external/avb:avbtool' conflicts with existing py_binary rule"
 		// So we need to solve all the "target ... is both a rule and a file" warnings first.
 		for dir := range dirs {
 			buildFileToTargets[dir] = append(buildFileToTargets[dir], BazelTarget{
 				name:      "bp2build_all_srcs",
 				content:   `filegroup(name = "bp2build_all_srcs", srcs = glob(["**/*"]), tags = ["manual"])`,
 				ruleClass: "filegroup",
 			})
 		}
 	}

 	return conversionResults{
 		buildFileToTargets:    buildFileToTargets,
 		moduleNameToPartition: moduleNameToPartition,
 	}, errs
 }

 // Convert a module and its deps and props into a Bazel macro/rule
 // representation in the BUILD file.
 func generateSoongModuleTarget(ctx bpToBuildContext, m blueprint.Module) (BazelTarget, error) {
 	props, err := getBuildProperties(ctx, m)

 	// TODO(b/163018919): DirectDeps can have duplicate (module, variant)
 	// items, if the modules are added using different DependencyTag. Figure
 	// out the implications of that.
 	depLabels := map[string]bool{}
 	if aModule, ok := m.(android.Module); ok {
 		ctx.VisitDirectDeps(aModule, func(depModule blueprint.Module) {
 			depLabels[qualifiedTargetLabel(ctx, depModule)] = true
 		})
 	}

 	for p := range ignoredPropNames {
 		delete(props.Attrs, p)
 	}
 	attributes := propsToAttributes(props.Attrs)

 	depLabelList := "[\n"
 	for depLabel := range depLabels {
 		depLabelList += fmt.Sprintf("        %q,\n", depLabel)
 	}
 	depLabelList += "    ]"

 	targetName := targetNameWithVariant(ctx, m)
 	return BazelTarget{
 		name:        targetName,
 		packageName: ctx.ModuleDir(m),
 		content: fmt.Sprintf(
 			soongModuleTargetTemplate,
 			targetName,
 			ctx.ModuleName(m),
 			canonicalizeModuleType(ctx.ModuleType(m)),
 			ctx.ModuleSubDir(m),
 			depLabelList,
 			attributes),
 	}, err
 }

 func getBuildProperties(ctx bpToBuildContext, m blueprint.Module) (BazelAttributes, error) {
 	// TODO: this omits properties for blueprint modules (blueprint_go_binary,
 	// bootstrap_go_binary, bootstrap_go_package), which will have to be handled separately.
 	if aModule, ok := m.(android.Module); ok {
 		return extractModuleProperties(aModule.GetProperties(), false)
 	}

 	return BazelAttributes{}, nil
 }

 // Generically extract module properties and types into a map, keyed by the module property name.
 func extractModuleProperties(props []interface{}, checkForDuplicateProperties bool) (BazelAttributes, error) {
 	ret := map[string]string{}

 	// Iterate over this android.Module's property structs.
 	for _, properties := range props {
 		propertiesValue := reflect.ValueOf(properties)
 		// Check that propertiesValue is a pointer to the Properties struct, like
 		// *cc.BaseLinkerProperties or *java.CompilerProperties.
 		//
 		// propertiesValue can also be type-asserted to the structs to
 		// manipulate internal props, if needed.
 		if isStructPtr(propertiesValue.Type()) {
 			structValue := propertiesValue.Elem()
 			ok, err := extractStructProperties(structValue, 0)
 			if err != nil {
 				return BazelAttributes{}, err
 			}
 			for k, v := range ok {
 				if existing, exists := ret[k]; checkForDuplicateProperties && exists {
 					return BazelAttributes{}, fmt.Errorf(
 						"%s (%v) is present in properties whereas it should be consolidated into a commonAttributes",
 						k, existing)
 				}
 				ret[k] = v
 			}
 		} else {
 			return BazelAttributes{},
 				fmt.Errorf(
 					"properties must be a pointer to a struct, got %T",
 					propertiesValue.Interface())
 		}
 	}

 	return BazelAttributes{
 		Attrs: ret,
 	}, nil
 }

 func isStructPtr(t reflect.Type) bool {
 	return t.Kind() == reflect.Ptr && t.Elem().Kind() == reflect.Struct
 }

 // prettyPrint a property value into the equivalent Starlark representation
 // recursively.
 func prettyPrint(propertyValue reflect.Value, indent int, emitZeroValues bool) (string, error) {
 	if !emitZeroValues && isZero(propertyValue) {
 		// A property value being set or unset actually matters -- Soong does set default
 		// values for unset properties, like system_shared_libs = ["libc", "libm", "libdl"] at
 		// https://cs.android.com/android/platform/superproject/+/main:build/soong/cc/linker.go;l=281-287;drc=f70926eef0b9b57faf04c17a1062ce50d209e480
 		//
 		// In Bazel-parlance, we would use "attr.<type>(default = <default
 		// value>)" to set the default value of unset attributes. In the cases
 		// where the bp2build converter didn't set the default value within the
 		// mutator when creating the BazelTargetModule, this would be a zero
 		// value. For those cases, we return an empty string so we don't
 		// unnecessarily generate empty values.
 		return "", nil
 	}

 	switch propertyValue.Kind() {
 	case reflect.String:
 		return fmt.Sprintf("\"%v\"", escapeString(propertyValue.String())), nil
 	case reflect.Bool:
 		return starlark_fmt.PrintBool(propertyValue.Bool()), nil
 	case reflect.Int, reflect.Uint, reflect.Int64:
 		return fmt.Sprintf("%v", propertyValue.Interface()), nil
 	case reflect.Ptr:
 		return prettyPrint(propertyValue.Elem(), indent, emitZeroValues)
 	case reflect.Slice:
 		elements := make([]string, 0, propertyValue.Len())
 		for i := 0; i < propertyValue.Len(); i++ {
 			val, err := prettyPrint(propertyValue.Index(i), indent, emitZeroValues)
 			if err != nil {
 				return "", err
 			}
 			if val != "" {
 				elements = append(elements, val)
 			}
 		}
 		return starlark_fmt.PrintList(elements, indent, func(s string) string {
 			return "%s"
 		}), nil

 	case reflect.Struct:
 		// Special cases where the bp2build sends additional information to the codegenerator
 		// by wrapping the attributes in a custom struct type.
 		if attr, ok := propertyValue.Interface().(bazel.Attribute); ok {
 			return prettyPrintAttribute(attr, indent)
 		} else if label, ok := propertyValue.Interface().(bazel.Label); ok {
 			return fmt.Sprintf("%q", label.Label), nil
 		}

 		// Sort and print the struct props by the key.
 		structProps, err := extractStructProperties(propertyValue, indent)

 		if err != nil {
 			return "", err
 		}

 		if len(structProps) == 0 {
 			return "", nil
 		}
 		return starlark_fmt.PrintDict(structProps, indent), nil
 	case reflect.Interface:
 		// TODO(b/164227191): implement pretty print for interfaces.
 		// Interfaces are used for for arch, multilib and target properties.
 		return "", nil
 	case reflect.Map:
 		if v, ok := propertyValue.Interface().(bazel.StringMapAttribute); ok {
 			return starlark_fmt.PrintStringStringDict(v, indent), nil
 		}
 		return "", fmt.Errorf("bp2build expects map of type map[string]string for field: %s", propertyValue)
 	default:
 		return "", fmt.Errorf(
 			"unexpected kind for property struct field: %s", propertyValue.Kind())
 	}
 }

 // Converts a reflected property struct value into a map of property names and property values,
 // which each property value correctly pretty-printed and indented at the right nest level,
 // since property structs can be nested. In Starlark, nested structs are represented as nested
 // dicts: https://docs.bazel.build/skylark/lib/dict.html
 func extractStructProperties(structValue reflect.Value, indent int) (map[string]string, error) {
 	if structValue.Kind() != reflect.Struct {
 		return map[string]string{}, fmt.Errorf("Expected a reflect.Struct type, but got %s", structValue.Kind())
 	}

 	var err error

 	ret := map[string]string{}
 	structType := structValue.Type()
 	for i := 0; i < structValue.NumField(); i++ {
 		field := structType.Field(i)
 		if shouldSkipStructField(field) {
 			continue
 		}

 		fieldValue := structValue.Field(i)
 		if isZero(fieldValue) {
 			// Ignore zero-valued fields
 			continue
 		}

 		// if the struct is embedded (anonymous), flatten the properties into the containing struct
 		if field.Anonymous {
 			if field.Type.Kind() == reflect.Ptr {
 				fieldValue = fieldValue.Elem()
 			}
 			if fieldValue.Type().Kind() == reflect.Struct {
 				propsToMerge, err := extractStructProperties(fieldValue, indent)
 				if err != nil {
 					return map[string]string{}, err
 				}
 				for prop, value := range propsToMerge {
 					ret[prop] = value
 				}
 				continue
 			}
 		}

 		propertyName := proptools.PropertyNameForField(field.Name)
 		var prettyPrintedValue string
 		prettyPrintedValue, err = prettyPrint(fieldValue, indent+1, false)
 		if err != nil {
 			return map[string]string{}, fmt.Errorf(
 				"Error while parsing property: %q. %s",
 				propertyName,
 				err)
 		}
 		if prettyPrintedValue != "" {
 			ret[propertyName] = prettyPrintedValue
 		}
 	}

 	return ret, nil
 }

 func isZero(value reflect.Value) bool {
 	switch value.Kind() {
 	case reflect.Func, reflect.Map, reflect.Slice:
 		return value.IsNil()
 	case reflect.Array:
 		valueIsZero := true
 		for i := 0; i < value.Len(); i++ {
 			valueIsZero = valueIsZero && isZero(value.Index(i))
 		}
 		return valueIsZero
 	case reflect.Struct:
 		valueIsZero := true
 		for i := 0; i < value.NumField(); i++ {
 			valueIsZero = valueIsZero && isZero(value.Field(i))
 		}
 		return valueIsZero
 	case reflect.Ptr:
 		if !value.IsNil() {
 			return isZero(reflect.Indirect(value))
 		} else {
 			return true
 		}
 	// Always print bool/strings, if you want a bool/string attribute to be able to take the default value, use a
 	// pointer instead
 	case reflect.Bool, reflect.String:
 		return false
 	default:
 		if !value.IsValid() {
 			return true
 		}
 		zeroValue := reflect.Zero(value.Type())
 		result := value.Interface() == zeroValue.Interface()
 		return result
 	}
 }

 func escapeString(s string) string {
 	s = strings.ReplaceAll(s, "\\", "\\\\")

 	// b/184026959: Reverse the application of some common control sequences.
 	// These must be generated literally in the BUILD file.
 	s = strings.ReplaceAll(s, "\t", "\\t")
 	s = strings.ReplaceAll(s, "\n", "\\n")
 	s = strings.ReplaceAll(s, "\r", "\\r")

 	return strings.ReplaceAll(s, "\"", "\\\"")
 }

 func targetNameWithVariant(c bpToBuildContext, logicModule blueprint.Module) string {
 	name := ""
 	if c.ModuleSubDir(logicModule) != "" {
 		// TODO(b/162720883): Figure out a way to drop the "--" variant suffixes.
 		name = c.ModuleName(logicModule) + "--" + c.ModuleSubDir(logicModule)
 	} else {
 		name = c.ModuleName(logicModule)
 	}

 	return strings.Replace(name, "//", "", 1)
 }

 func qualifiedTargetLabel(c bpToBuildContext, logicModule blueprint.Module) string {
 	return fmt.Sprintf("//%s:%s", c.ModuleDir(logicModule), targetNameWithVariant(c, logicModule))
 }
	// Copyright 2020 Google Inc. All rights reserved.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	package bp2build

	/*
	For shareable/common functionality for conversion from soong-module to build files
	for queryview/bp2build
	*/

	import (
	"fmt"
	"reflect"
	"sort"
	"strings"

	"android/soong/android"
	"android/soong/bazel"
	"android/soong/starlark_fmt"
	"github.com/google/blueprint"
	"github.com/google/blueprint/proptools"
	)

	type BazelAttributes struct {
	Attrs map[string]string
	}

	type BazelLoadSymbol struct {
	// The name of the symbol in the file being loaded
	symbol string
	// The name the symbol wil have in this file. Can be left blank to use the same name as symbol.
	alias string
	}

	type BazelLoad struct {
	file string
	symbols []BazelLoadSymbol
	}

	type BazelTarget struct {
	name string
	packageName string
	content string
	ruleClass string
	loads []BazelLoad
	}

	// Label is the fully qualified Bazel label constructed from the BazelTarget's
	// package name and target name.
	func (t BazelTarget) Label() string {
	if t.packageName == "." {
	return "//:" + t.name
	} else {
	return "//" + t.packageName + ":" + t.name
	}
	}

	// PackageName returns the package of the Bazel target.
	// Defaults to root of tree.
	func (t BazelTarget) PackageName() string {
	if t.packageName == "" {
	return "."
	}
	return t.packageName
	}

	// BazelTargets is a typedef for a slice of BazelTarget objects.
	type BazelTargets []BazelTarget

	func (targets BazelTargets) packageRule() *BazelTarget {
	for _, target := range targets {
	if target.ruleClass == "package" {
	return &target
	}
	}
	return nil
	}

	// sort a list of BazelTargets in-place, by name, and by generated/handcrafted types.
	func (targets BazelTargets) sort() {
	sort.Slice(targets, func(i, j int) bool {
	return targets[i].name < targets[j].name
	})
	}

	// String returns the string representation of BazelTargets, without load
	// statements (use LoadStatements for that), since the targets are usually not
	// adjacent to the load statements at the top of the BUILD file.
	func (targets BazelTargets) String() string {
	var res strings.Builder
	for i, target := range targets {
	if target.ruleClass != "package" {
	res.WriteString(target.content)
	}
	if i != len(targets)-1 {
	res.WriteString("\n\n")
	}
	}
	return res.String()
	}

	// LoadStatements return the string representation of the sorted and deduplicated
	// Starlark rule load statements needed by a group of BazelTargets.
	func (targets BazelTargets) LoadStatements() string {
	// First, merge all the load statements from all the targets onto one list
	bzlToLoadedSymbols := map[string][]BazelLoadSymbol{}
	for _, target := range targets {
	for _, load := range target.loads {
	outer:
	for _, symbol := range load.symbols {
	alias := symbol.alias
	if alias == "" {
	alias = symbol.symbol
	}
	for _, otherSymbol := range bzlToLoadedSymbols[load.file] {
	otherAlias := otherSymbol.alias
	if otherAlias == "" {
	otherAlias = otherSymbol.symbol
	}
	if symbol.symbol == otherSymbol.symbol && alias == otherAlias {
	continue outer
	} else if alias == otherAlias {
	panic(fmt.Sprintf("Conflicting destination (%s) for loads of %s and %s", alias, symbol.symbol, otherSymbol.symbol))
	}
	}
	bzlToLoadedSymbols[load.file] = append(bzlToLoadedSymbols[load.file], symbol)
	}
	}
	}

	var loadStatements strings.Builder
	for i, bzl := range android.SortedKeys(bzlToLoadedSymbols) {
	symbols := bzlToLoadedSymbols[bzl]
	loadStatements.WriteString("load(\"")
	loadStatements.WriteString(bzl)
	loadStatements.WriteString("\", ")
	sort.Slice(symbols, func(i, j int) bool {
	if symbols[i].symbol < symbols[j].symbol {
	return true
	}
	return symbols[i].alias < symbols[j].alias
	})
	for j, symbol := range symbols {
	if symbol.alias != "" && symbol.alias != symbol.symbol {
	loadStatements.WriteString(symbol.alias)
	loadStatements.WriteString(" = ")
	}
	loadStatements.WriteString("\"")
	loadStatements.WriteString(symbol.symbol)
	loadStatements.WriteString("\"")
	if j != len(symbols)-1 {
	loadStatements.WriteString(", ")
	}
	}
	loadStatements.WriteString(")")
	if i != len(bzlToLoadedSymbols)-1 {
	loadStatements.WriteString("\n")
	}
	}
	return loadStatements.String()
	}

	type bpToBuildContext interface {
	ModuleName(module blueprint.Module) string
	ModuleDir(module blueprint.Module) string
	ModuleSubDir(module blueprint.Module) string
	ModuleType(module blueprint.Module) string

	VisitAllModules(visit func(blueprint.Module))
	VisitDirectDeps(module blueprint.Module, visit func(blueprint.Module))
	}

	type CodegenContext struct {
	config android.Config
	context *android.Context
	mode CodegenMode
	additionalDeps []string
	unconvertedDepMode unconvertedDepsMode
	topDir string
	}

	func (ctx *CodegenContext) Mode() CodegenMode {
	return ctx.mode
	}

	// CodegenMode is an enum to differentiate code-generation modes.
	type CodegenMode int

	const (
	// QueryView - generate BUILD files with targets representing fully mutated
	// Soong modules, representing the fully configured Soong module graph with
	// variants and dependency edges.
	//
	// This mode is used for discovering and introspecting the existing Soong
	// module graph.
	QueryView CodegenMode = iota
	)

	type unconvertedDepsMode int

	const (
	// Include a warning in conversion metrics about converted modules with unconverted direct deps
	warnUnconvertedDeps unconvertedDepsMode = iota
	// Error and fail conversion if encountering a module with unconverted direct deps
	// Enabled by setting environment variable `BP2BUILD_ERROR_UNCONVERTED`
	errorModulesUnconvertedDeps
	)

	func (mode CodegenMode) String() string {
	switch mode {
	case QueryView:
	return "QueryView"
	default:
	return fmt.Sprintf("%d", mode)
	}
	}

	// AddNinjaFileDeps adds dependencies on the specified files to be added to the ninja manifest. The
	// primary builder will be rerun whenever the specified files are modified. Allows us to fulfill the
	// PathContext interface in order to add dependencies on hand-crafted BUILD files. Note: must also
	// call AdditionalNinjaDeps and add them manually to the ninja file.
	func (ctx *CodegenContext) AddNinjaFileDeps(deps ...string) {
	ctx.additionalDeps = append(ctx.additionalDeps, deps...)
	}

	// AdditionalNinjaDeps returns additional ninja deps added by CodegenContext
	func (ctx *CodegenContext) AdditionalNinjaDeps() []string {
	return ctx.additionalDeps
	}

	func (ctx *CodegenContext) Config() android.Config { return ctx.config }
	func (ctx CodegenContext) Context() android.Context { return ctx.context }

	// NewCodegenContext creates a wrapper context that conforms to PathContext for
	// writing BUILD files in the output directory.
	func NewCodegenContext(config android.Config, context android.Context, mode CodegenMode, topDir string) CodegenContext {
	var unconvertedDeps unconvertedDepsMode
	return &CodegenContext{
	context: context,
	config: config,
	mode: mode,
	unconvertedDepMode: unconvertedDeps,
	topDir: topDir,
	}
	}

	// props is an unsorted map. This function ensures that
	// the generated attributes are sorted to ensure determinism.
	func propsToAttributes(props map[string]string) string {
	var attributes string
	for _, propName := range android.SortedKeys(props) {
	attributes += fmt.Sprintf(" %s = %s,\n", propName, props[propName])
	}
	return attributes
	}

	type conversionResults struct {
	buildFileToTargets map[string]BazelTargets
	moduleNameToPartition map[string]string
	}

	func (r conversionResults) BuildDirToTargets() map[string]BazelTargets {
	return r.buildFileToTargets
	}

	func GenerateBazelTargets(ctx *CodegenContext, generateFilegroups bool) (conversionResults, []error) {
	ctx.Context().BeginEvent("GenerateBazelTargets")
	defer ctx.Context().EndEvent("GenerateBazelTargets")
	buildFileToTargets := make(map[string]BazelTargets)

	dirs := make(map[string]bool)
	moduleNameToPartition := make(map[string]string)

	var errs []error

	bpCtx := ctx.Context()
	bpCtx.VisitAllModules(func(m blueprint.Module) {
	dir := bpCtx.ModuleDir(m)
	dirs[dir] = true

	var targets []BazelTarget

	switch ctx.Mode() {
	case QueryView:
	// Blocklist certain module types from being generated.
	if canonicalizeModuleType(bpCtx.ModuleType(m)) == "package" {
	// package module name contain slashes, and thus cannot
	// be mapped cleanly to a bazel label.
	return
	}
	t, err := generateSoongModuleTarget(bpCtx, m)
	if err != nil {
	errs = append(errs, err)
	}
	targets = append(targets, t)
	default:
	errs = append(errs, fmt.Errorf("Unknown code-generation mode: %s", ctx.Mode()))
	return
	}

	for _, target := range targets {
	targetDir := target.PackageName()
	buildFileToTargets[targetDir] = append(buildFileToTargets[targetDir], target)
	}
	})

	if len(errs) > 0 {
	return conversionResults{}, errs
	}

	if generateFilegroups {
	// Add a filegroup target that exposes all sources in the subtree of this package
	// NOTE: This also means we generate a BUILD file for every Android.bp file (as long as it has at least one module)
	//
	// This works because: https://bazel.build/reference/be/functions#exports_files
	// "As a legacy behaviour, also files mentioned as input to a rule are exported with the
	// default visibility until the flag --incompatible_no_implicit_file_export is flipped. However, this behavior
	// should not be relied upon and actively migrated away from."
	//
	// TODO(b/198619163): We should change this to export_files(glob(["*/"])) instead, but doing that causes these errors:
	// "Error in exports_files: generated label '//external/avb:avbtool' conflicts with existing py_binary rule"
	// So we need to solve all the "target ... is both a rule and a file" warnings first.
	for dir := range dirs {
	buildFileToTargets[dir] = append(buildFileToTargets[dir], BazelTarget{
	name: "bp2build_all_srcs",
	content: `filegroup(name = "bp2build_all_srcs", srcs = glob(["*/"]), tags = ["manual"])`,
	ruleClass: "filegroup",
	})
	}
	}

	return conversionResults{
	buildFileToTargets: buildFileToTargets,
	moduleNameToPartition: moduleNameToPartition,
	}, errs
	}

	// Convert a module and its deps and props into a Bazel macro/rule
	// representation in the BUILD file.
	func generateSoongModuleTarget(ctx bpToBuildContext, m blueprint.Module) (BazelTarget, error) {
	props, err := getBuildProperties(ctx, m)

	// TODO(b/163018919): DirectDeps can have duplicate (module, variant)
	// items, if the modules are added using different DependencyTag. Figure
	// out the implications of that.
	depLabels := map[string]bool{}
	if aModule, ok := m.(android.Module); ok {
	ctx.VisitDirectDeps(aModule, func(depModule blueprint.Module) {
	depLabels[qualifiedTargetLabel(ctx, depModule)] = true
	})
	}

	for p := range ignoredPropNames {
	delete(props.Attrs, p)
	}
	attributes := propsToAttributes(props.Attrs)

	depLabelList := "[\n"
	for depLabel := range depLabels {
	depLabelList += fmt.Sprintf(" %q,\n", depLabel)
	}
	depLabelList += " ]"

	targetName := targetNameWithVariant(ctx, m)
	return BazelTarget{
	name: targetName,
	packageName: ctx.ModuleDir(m),
	content: fmt.Sprintf(
	soongModuleTargetTemplate,
	targetName,
	ctx.ModuleName(m),
	canonicalizeModuleType(ctx.ModuleType(m)),
	ctx.ModuleSubDir(m),
	depLabelList,
	attributes),
	}, err
	}

	func getBuildProperties(ctx bpToBuildContext, m blueprint.Module) (BazelAttributes, error) {
	// TODO: this omits properties for blueprint modules (blueprint_go_binary,
	// bootstrap_go_binary, bootstrap_go_package), which will have to be handled separately.
	if aModule, ok := m.(android.Module); ok {
	return extractModuleProperties(aModule.GetProperties(), false)
	}

	return BazelAttributes{}, nil
	}

	// Generically extract module properties and types into a map, keyed by the module property name.
	func extractModuleProperties(props []interface{}, checkForDuplicateProperties bool) (BazelAttributes, error) {
	ret := map[string]string{}

	// Iterate over this android.Module's property structs.
	for _, properties := range props {
	propertiesValue := reflect.ValueOf(properties)
	// Check that propertiesValue is a pointer to the Properties struct, like
	// cc.BaseLinkerProperties or java.CompilerProperties.
	//
	// propertiesValue can also be type-asserted to the structs to
	// manipulate internal props, if needed.
	if isStructPtr(propertiesValue.Type()) {
	structValue := propertiesValue.Elem()
	ok, err := extractStructProperties(structValue, 0)
	if err != nil {
	return BazelAttributes{}, err
	}
	for k, v := range ok {
	if existing, exists := ret[k]; checkForDuplicateProperties && exists {
	return BazelAttributes{}, fmt.Errorf(
	"%s (%v) is present in properties whereas it should be consolidated into a commonAttributes",
	k, existing)
	}
	ret[k] = v
	}
	} else {
	return BazelAttributes{},
	fmt.Errorf(
	"properties must be a pointer to a struct, got %T",
	propertiesValue.Interface())
	}
	}

	return BazelAttributes{
	Attrs: ret,
	}, nil
	}

	func isStructPtr(t reflect.Type) bool {
	return t.Kind() == reflect.Ptr && t.Elem().Kind() == reflect.Struct
	}

	// prettyPrint a property value into the equivalent Starlark representation
	// recursively.
	func prettyPrint(propertyValue reflect.Value, indent int, emitZeroValues bool) (string, error) {
	if !emitZeroValues && isZero(propertyValue) {
	// A property value being set or unset actually matters -- Soong does set default
	// values for unset properties, like system_shared_libs = ["libc", "libm", "libdl"] at
	// https://cs.android.com/android/platform/superproject/+/main:build/soong/cc/linker.go;l=281-287;drc=f70926eef0b9b57faf04c17a1062ce50d209e480
	//
	// In Bazel-parlance, we would use "attr.<type>(default = <default
	// value>)" to set the default value of unset attributes. In the cases
	// where the bp2build converter didn't set the default value within the
	// mutator when creating the BazelTargetModule, this would be a zero
	// value. For those cases, we return an empty string so we don't
	// unnecessarily generate empty values.
	return "", nil
	}

	switch propertyValue.Kind() {
	case reflect.String:
	return fmt.Sprintf("\"%v\"", escapeString(propertyValue.String())), nil
	case reflect.Bool:
	return starlark_fmt.PrintBool(propertyValue.Bool()), nil
	case reflect.Int, reflect.Uint, reflect.Int64:
	return fmt.Sprintf("%v", propertyValue.Interface()), nil
	case reflect.Ptr:
	return prettyPrint(propertyValue.Elem(), indent, emitZeroValues)
	case reflect.Slice:
	elements := make([]string, 0, propertyValue.Len())
	for i := 0; i < propertyValue.Len(); i++ {
	val, err := prettyPrint(propertyValue.Index(i), indent, emitZeroValues)
	if err != nil {
	return "", err
	}
	if val != "" {
	elements = append(elements, val)
	}
	}
	return starlark_fmt.PrintList(elements, indent, func(s string) string {
	return "%s"
	}), nil

	case reflect.Struct:
	// Special cases where the bp2build sends additional information to the codegenerator
	// by wrapping the attributes in a custom struct type.
	if attr, ok := propertyValue.Interface().(bazel.Attribute); ok {
	return prettyPrintAttribute(attr, indent)
	} else if label, ok := propertyValue.Interface().(bazel.Label); ok {
	return fmt.Sprintf("%q", label.Label), nil
	}

	// Sort and print the struct props by the key.
	structProps, err := extractStructProperties(propertyValue, indent)

	if err != nil {
	return "", err
	}

	if len(structProps) == 0 {
	return "", nil
	}
	return starlark_fmt.PrintDict(structProps, indent), nil
	case reflect.Interface:
	// TODO(b/164227191): implement pretty print for interfaces.
	// Interfaces are used for for arch, multilib and target properties.
	return "", nil
	case reflect.Map:
	if v, ok := propertyValue.Interface().(bazel.StringMapAttribute); ok {
	return starlark_fmt.PrintStringStringDict(v, indent), nil
	}
	return "", fmt.Errorf("bp2build expects map of type map[string]string for field: %s", propertyValue)
	default:
	return "", fmt.Errorf(
	"unexpected kind for property struct field: %s", propertyValue.Kind())
	}
	}

	// Converts a reflected property struct value into a map of property names and property values,
	// which each property value correctly pretty-printed and indented at the right nest level,
	// since property structs can be nested. In Starlark, nested structs are represented as nested
	// dicts: https://docs.bazel.build/skylark/lib/dict.html
	func extractStructProperties(structValue reflect.Value, indent int) (map[string]string, error) {
	if structValue.Kind() != reflect.Struct {
	return map[string]string{}, fmt.Errorf("Expected a reflect.Struct type, but got %s", structValue.Kind())
	}

	var err error

	ret := map[string]string{}
	structType := structValue.Type()
	for i := 0; i < structValue.NumField(); i++ {
	field := structType.Field(i)
	if shouldSkipStructField(field) {
	continue
	}

	fieldValue := structValue.Field(i)
	if isZero(fieldValue) {
	// Ignore zero-valued fields
	continue
	}

	// if the struct is embedded (anonymous), flatten the properties into the containing struct
	if field.Anonymous {
	if field.Type.Kind() == reflect.Ptr {
	fieldValue = fieldValue.Elem()
	}
	if fieldValue.Type().Kind() == reflect.Struct {
	propsToMerge, err := extractStructProperties(fieldValue, indent)
	if err != nil {
	return map[string]string{}, err
	}
	for prop, value := range propsToMerge {
	ret[prop] = value
	}
	continue
	}
	}

	propertyName := proptools.PropertyNameForField(field.Name)
	var prettyPrintedValue string
	prettyPrintedValue, err = prettyPrint(fieldValue, indent+1, false)
	if err != nil {
	return map[string]string{}, fmt.Errorf(
	"Error while parsing property: %q. %s",
	propertyName,
	err)
	}
	if prettyPrintedValue != "" {
	ret[propertyName] = prettyPrintedValue
	}
	}

	return ret, nil
	}

	func isZero(value reflect.Value) bool {
	switch value.Kind() {
	case reflect.Func, reflect.Map, reflect.Slice:
	return value.IsNil()
	case reflect.Array:
	valueIsZero := true
	for i := 0; i < value.Len(); i++ {
	valueIsZero = valueIsZero && isZero(value.Index(i))
	}
	return valueIsZero
	case reflect.Struct:
	valueIsZero := true
	for i := 0; i < value.NumField(); i++ {
	valueIsZero = valueIsZero && isZero(value.Field(i))
	}
	return valueIsZero
	case reflect.Ptr:
	if !value.IsNil() {
	return isZero(reflect.Indirect(value))
	} else {
	return true
	}
	// Always print bool/strings, if you want a bool/string attribute to be able to take the default value, use a
	// pointer instead
	case reflect.Bool, reflect.String:
	return false
	default:
	if !value.IsValid() {
	return true
	}
	zeroValue := reflect.Zero(value.Type())
	result := value.Interface() == zeroValue.Interface()
	return result
	}
	}

	func escapeString(s string) string {
	s = strings.ReplaceAll(s, "\\", "\\\\")

	// b/184026959: Reverse the application of some common control sequences.
	// These must be generated literally in the BUILD file.
	s = strings.ReplaceAll(s, "\t", "\\t")
	s = strings.ReplaceAll(s, "\n", "\\n")
	s = strings.ReplaceAll(s, "\r", "\\r")

	return strings.ReplaceAll(s, "\"", "\\\"")
	}

	func targetNameWithVariant(c bpToBuildContext, logicModule blueprint.Module) string {
	name := ""
	if c.ModuleSubDir(logicModule) != "" {
	// TODO(b/162720883): Figure out a way to drop the "--" variant suffixes.
	name = c.ModuleName(logicModule) + "--" + c.ModuleSubDir(logicModule)
	} else {
	name = c.ModuleName(logicModule)
	}

	return strings.Replace(name, "//", "", 1)
	}

	func qualifiedTargetLabel(c bpToBuildContext, logicModule blueprint.Module) string {
	return fmt.Sprintf("//%s:%s", c.ModuleDir(logicModule), targetNameWithVariant(c, logicModule))
	}