platform_build_soong/cc/bp2build.go

// Copyright 2021 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 cc

import (
	"fmt"
	"path/filepath"
	"regexp"
	"strings"

	"android/soong/android"
	"android/soong/bazel"

	"github.com/google/blueprint"

	"github.com/google/blueprint/proptools"
)

const (
	cSrcPartition     = "c"
	asSrcPartition    = "as"
	cppSrcPartition   = "cpp"
	protoSrcPartition = "proto"
)

var (
	// ignoring case, checks for proto or protos as an independent word in the name, whether at the
	// beginning, end, or middle. e.g. "proto.foo", "bar-protos", "baz_proto_srcs" would all match
	filegroupLikelyProtoPattern = regexp.MustCompile("(?i)(^|[^a-z])proto(s)?([^a-z]|$)")
)

// staticOrSharedAttributes are the Bazel-ified versions of StaticOrSharedProperties --
// properties which apply to either the shared or static version of a cc_library module.
type staticOrSharedAttributes struct {
	Srcs    bazel.LabelListAttribute
	Srcs_c  bazel.LabelListAttribute
	Srcs_as bazel.LabelListAttribute
	Hdrs    bazel.LabelListAttribute
	Copts   bazel.StringListAttribute

	Deps                              bazel.LabelListAttribute
	Implementation_deps               bazel.LabelListAttribute
	Dynamic_deps                      bazel.LabelListAttribute
	Implementation_dynamic_deps       bazel.LabelListAttribute
	Whole_archive_deps                bazel.LabelListAttribute
	Implementation_whole_archive_deps bazel.LabelListAttribute

	System_dynamic_deps bazel.LabelListAttribute

	Enabled bazel.BoolAttribute
}

func groupSrcsByExtension(ctx android.BazelConversionPathContext, srcs bazel.LabelListAttribute) bazel.PartitionToLabelListAttribute {
	// Check that a module is a filegroup type
	isFilegroup := func(m blueprint.Module) bool {
		return ctx.OtherModuleType(m) == "filegroup"
	}

	// Convert filegroup dependencies into extension-specific filegroups filtered in the filegroup.bzl
	// macro.
	addSuffixForFilegroup := func(suffix string) bazel.LabelMapper {
		return func(ctx bazel.OtherModuleContext, label bazel.Label) (string, bool) {
			m, exists := ctx.ModuleFromName(label.OriginalModuleName)
			labelStr := label.Label
			if !exists || !isFilegroup(m) {
				return labelStr, false
			}
			return labelStr + suffix, true
		}
	}

	isProtoFilegroup := func(ctx bazel.OtherModuleContext, label bazel.Label) (string, bool) {
		m, exists := ctx.ModuleFromName(label.OriginalModuleName)
		labelStr := label.Label
		if !exists || !isFilegroup(m) {
			return labelStr, false
		}
		likelyProtos := filegroupLikelyProtoPattern.MatchString(label.OriginalModuleName)
		return labelStr, likelyProtos
	}

	// TODO(b/190006308): Handle language detection of sources in a Bazel rule.
	partitioned := bazel.PartitionLabelListAttribute(ctx, &srcs, bazel.LabelPartitions{
		protoSrcPartition: bazel.LabelPartition{Extensions: []string{".proto"}, LabelMapper: isProtoFilegroup},
		cSrcPartition:     bazel.LabelPartition{Extensions: []string{".c"}, LabelMapper: addSuffixForFilegroup("_c_srcs")},
		asSrcPartition:    bazel.LabelPartition{Extensions: []string{".s", ".S"}, LabelMapper: addSuffixForFilegroup("_as_srcs")},
		// C++ is the "catch-all" group, and comprises generated sources because we don't
		// know the language of these sources until the genrule is executed.
		cppSrcPartition: bazel.LabelPartition{Extensions: []string{".cpp", ".cc", ".cxx", ".mm"}, LabelMapper: addSuffixForFilegroup("_cpp_srcs"), Keep_remainder: true},
	})

	return partitioned
}

// bp2BuildParseLibProps returns the attributes for a variant of a cc_library.
func bp2BuildParseLibProps(ctx android.BazelConversionPathContext, module *Module, isStatic bool) staticOrSharedAttributes {
	lib, ok := module.compiler.(*libraryDecorator)
	if !ok {
		return staticOrSharedAttributes{}
	}
	return bp2buildParseStaticOrSharedProps(ctx, module, lib, isStatic)
}

// bp2buildParseSharedProps returns the attributes for the shared variant of a cc_library.
func bp2BuildParseSharedProps(ctx android.BazelConversionPathContext, module *Module) staticOrSharedAttributes {
	return bp2BuildParseLibProps(ctx, module, false)
}

// bp2buildParseStaticProps returns the attributes for the static variant of a cc_library.
func bp2BuildParseStaticProps(ctx android.BazelConversionPathContext, module *Module) staticOrSharedAttributes {
	return bp2BuildParseLibProps(ctx, module, true)
}

type depsPartition struct {
	export         bazel.LabelList
	implementation bazel.LabelList
}

type bazelLabelForDepsFn func(android.BazelConversionPathContext, []string) bazel.LabelList

func maybePartitionExportedAndImplementationsDeps(ctx android.BazelConversionPathContext, exportsDeps bool, allDeps, exportedDeps []string, fn bazelLabelForDepsFn) depsPartition {
	if !exportsDeps {
		return depsPartition{
			implementation: fn(ctx, allDeps),
		}
	}

	implementation, export := android.FilterList(allDeps, exportedDeps)

	return depsPartition{
		export:         fn(ctx, export),
		implementation: fn(ctx, implementation),
	}
}

type bazelLabelForDepsExcludesFn func(android.BazelConversionPathContext, []string, []string) bazel.LabelList

func maybePartitionExportedAndImplementationsDepsExcludes(ctx android.BazelConversionPathContext, exportsDeps bool, allDeps, excludes, exportedDeps []string, fn bazelLabelForDepsExcludesFn) depsPartition {
	if !exportsDeps {
		return depsPartition{
			implementation: fn(ctx, allDeps, excludes),
		}
	}
	implementation, export := android.FilterList(allDeps, exportedDeps)

	return depsPartition{
		export:         fn(ctx, export, excludes),
		implementation: fn(ctx, implementation, excludes),
	}
}

func bp2buildParseStaticOrSharedProps(ctx android.BazelConversionPathContext, module *Module, lib *libraryDecorator, isStatic bool) staticOrSharedAttributes {
	attrs := staticOrSharedAttributes{}

	setAttrs := func(axis bazel.ConfigurationAxis, config string, props StaticOrSharedProperties) {
		attrs.Copts.SetSelectValue(axis, config, parseCommandLineFlags(props.Cflags, filterOutStdFlag))
		attrs.Srcs.SetSelectValue(axis, config, android.BazelLabelForModuleSrc(ctx, props.Srcs))
		attrs.System_dynamic_deps.SetSelectValue(axis, config, bazelLabelForSharedDeps(ctx, props.System_shared_libs))

		staticDeps := maybePartitionExportedAndImplementationsDeps(ctx, true, props.Static_libs, props.Export_static_lib_headers, bazelLabelForStaticDeps)
		attrs.Deps.SetSelectValue(axis, config, staticDeps.export)
		attrs.Implementation_deps.SetSelectValue(axis, config, staticDeps.implementation)

		sharedDeps := maybePartitionExportedAndImplementationsDeps(ctx, true, props.Shared_libs, props.Export_shared_lib_headers, bazelLabelForSharedDeps)
		attrs.Dynamic_deps.SetSelectValue(axis, config, sharedDeps.export)
		attrs.Implementation_dynamic_deps.SetSelectValue(axis, config, sharedDeps.implementation)

		attrs.Whole_archive_deps.SetSelectValue(axis, config, bazelLabelForWholeDeps(ctx, props.Whole_static_libs))
		attrs.Enabled.SetSelectValue(axis, config, props.Enabled)
	}
	// system_dynamic_deps distinguishes between nil/empty list behavior:
	//    nil -> use default values
	//    empty list -> no values specified
	attrs.System_dynamic_deps.ForceSpecifyEmptyList = true

	if isStatic {
		for axis, configToProps := range module.GetArchVariantProperties(ctx, &StaticProperties{}) {
			for config, props := range configToProps {
				if staticOrSharedProps, ok := props.(*StaticProperties); ok {
					setAttrs(axis, config, staticOrSharedProps.Static)
				}
			}
		}
	} else {
		for axis, configToProps := range module.GetArchVariantProperties(ctx, &SharedProperties{}) {
			for config, props := range configToProps {
				if staticOrSharedProps, ok := props.(*SharedProperties); ok {
					setAttrs(axis, config, staticOrSharedProps.Shared)
				}
			}
		}
	}

	partitionedSrcs := groupSrcsByExtension(ctx, attrs.Srcs)
	attrs.Srcs = partitionedSrcs[cppSrcPartition]
	attrs.Srcs_c = partitionedSrcs[cSrcPartition]
	attrs.Srcs_as = partitionedSrcs[asSrcPartition]

	if !partitionedSrcs[protoSrcPartition].IsEmpty() {
		// TODO(b/208815215): determine whether this is used and add support if necessary
		ctx.ModuleErrorf("Migrating static/shared only proto srcs is not currently supported")
	}

	return attrs
}

// Convenience struct to hold all attributes parsed from prebuilt properties.
type prebuiltAttributes struct {
	Src bazel.LabelAttribute
}

// NOTE: Used outside of Soong repo project, in the clangprebuilts.go bootstrap_go_package
func Bp2BuildParsePrebuiltLibraryProps(ctx android.BazelConversionPathContext, module *Module) prebuiltAttributes {
	var srcLabelAttribute bazel.LabelAttribute

	for axis, configToProps := range module.GetArchVariantProperties(ctx, &prebuiltLinkerProperties{}) {
		for config, props := range configToProps {
			if prebuiltLinkerProperties, ok := props.(*prebuiltLinkerProperties); ok {
				if len(prebuiltLinkerProperties.Srcs) > 1 {
					ctx.ModuleErrorf("Bp2BuildParsePrebuiltLibraryProps: Expected at most once source file for %s %s\n", axis, config)
					continue
				} else if len(prebuiltLinkerProperties.Srcs) == 0 {
					continue
				}
				src := android.BazelLabelForModuleSrcSingle(ctx, prebuiltLinkerProperties.Srcs[0])
				srcLabelAttribute.SetSelectValue(axis, config, src)
			}
		}
	}

	return prebuiltAttributes{
		Src: srcLabelAttribute,
	}
}

type baseAttributes struct {
	compilerAttributes
	linkerAttributes

	protoDependency *bazel.LabelAttribute
}

// Convenience struct to hold all attributes parsed from compiler properties.
type compilerAttributes struct {
	// Options for all languages
	copts bazel.StringListAttribute
	// Assembly options and sources
	asFlags bazel.StringListAttribute
	asSrcs  bazel.LabelListAttribute
	// C options and sources
	conlyFlags bazel.StringListAttribute
	cSrcs      bazel.LabelListAttribute
	// C++ options and sources
	cppFlags bazel.StringListAttribute
	srcs     bazel.LabelListAttribute

	hdrs bazel.LabelListAttribute

	rtti bazel.BoolAttribute

	// Not affected by arch variants
	stl    *string
	cStd   *string
	cppStd *string

	localIncludes    bazel.StringListAttribute
	absoluteIncludes bazel.StringListAttribute

	includes BazelIncludes

	protoSrcs bazel.LabelListAttribute
}

type filterOutFn func(string) bool

func filterOutStdFlag(flag string) bool {
	return strings.HasPrefix(flag, "-std=")
}

func parseCommandLineFlags(soongFlags []string, filterOut filterOutFn) []string {
	var result []string
	for _, flag := range soongFlags {
		if filterOut != nil && filterOut(flag) {
			continue
		}
		// Soong's cflags can contain spaces, like `-include header.h`. For
		// Bazel's copts, split them up to be compatible with the
		// no_copts_tokenization feature.
		result = append(result, strings.Split(flag, " ")...)
	}
	return result
}

func (ca *compilerAttributes) bp2buildForAxisAndConfig(ctx android.BazelConversionPathContext, axis bazel.ConfigurationAxis, config string, props *BaseCompilerProperties) {
	// If there's arch specific srcs or exclude_srcs, generate a select entry for it.
	// TODO(b/186153868): do this for OS specific srcs and exclude_srcs too.
	if srcsList, ok := parseSrcs(ctx, props); ok {
		ca.srcs.SetSelectValue(axis, config, srcsList)
	}

	localIncludeDirs := props.Local_include_dirs
	if axis == bazel.NoConfigAxis {
		ca.cStd, ca.cppStd = bp2buildResolveCppStdValue(props.C_std, props.Cpp_std, props.Gnu_extensions)
		if includeBuildDirectory(props.Include_build_directory) {
			localIncludeDirs = append(localIncludeDirs, ".")
		}
	}

	ca.absoluteIncludes.SetSelectValue(axis, config, props.Include_dirs)
	ca.localIncludes.SetSelectValue(axis, config, localIncludeDirs)

	// In Soong, cflags occur on the command line before -std=<val> flag, resulting in the value being
	// overridden. In Bazel we always allow overriding, via flags; however, this can cause
	// incompatibilities, so we remove "-std=" flags from Cflag properties while leaving it in other
	// cases.
	ca.copts.SetSelectValue(axis, config, parseCommandLineFlags(props.Cflags, filterOutStdFlag))
	ca.asFlags.SetSelectValue(axis, config, parseCommandLineFlags(props.Asflags, nil))
	ca.conlyFlags.SetSelectValue(axis, config, parseCommandLineFlags(props.Conlyflags, nil))
	ca.cppFlags.SetSelectValue(axis, config, parseCommandLineFlags(props.Cppflags, nil))
	ca.rtti.SetSelectValue(axis, config, props.Rtti)
}

func (ca *compilerAttributes) convertStlProps(ctx android.ArchVariantContext, module *Module) {
	stlPropsByArch := module.GetArchVariantProperties(ctx, &StlProperties{})
	for _, configToProps := range stlPropsByArch {
		for _, props := range configToProps {
			if stlProps, ok := props.(*StlProperties); ok {
				if stlProps.Stl == nil {
					continue
				}
				if ca.stl == nil {
					ca.stl = stlProps.Stl
				} else if ca.stl != stlProps.Stl {
					ctx.ModuleErrorf("Unsupported conversion: module with different stl for different variants: %s and %s", *ca.stl, stlProps.Stl)
				}
			}
		}
	}
}

func (ca *compilerAttributes) convertProductVariables(ctx android.BazelConversionPathContext, productVariableProps android.ProductConfigProperties) {
	productVarPropNameToAttribute := map[string]*bazel.StringListAttribute{
		"Cflags":   &ca.copts,
		"Asflags":  &ca.asFlags,
		"CppFlags": &ca.cppFlags,
	}
	for propName, attr := range productVarPropNameToAttribute {
		if productConfigProps, exists := productVariableProps[propName]; exists {
			for productConfigProp, prop := range productConfigProps {
				flags, ok := prop.([]string)
				if !ok {
					ctx.ModuleErrorf("Could not convert product variable %s property", proptools.PropertyNameForField(propName))
				}
				newFlags, _ := bazel.TryVariableSubstitutions(flags, productConfigProp.Name)
				attr.SetSelectValue(productConfigProp.ConfigurationAxis(), productConfigProp.SelectKey(), newFlags)
			}
		}
	}
}

func (ca *compilerAttributes) finalize(ctx android.BazelConversionPathContext, implementationHdrs bazel.LabelListAttribute) {
	ca.srcs.ResolveExcludes()
	partitionedSrcs := groupSrcsByExtension(ctx, ca.srcs)

	ca.protoSrcs = partitionedSrcs[protoSrcPartition]

	for p, lla := range partitionedSrcs {
		// if there are no sources, there is no need for headers
		if lla.IsEmpty() {
			continue
		}
		lla.Append(implementationHdrs)
		partitionedSrcs[p] = lla
	}

	ca.srcs = partitionedSrcs[cppSrcPartition]
	ca.cSrcs = partitionedSrcs[cSrcPartition]
	ca.asSrcs = partitionedSrcs[asSrcPartition]

	ca.absoluteIncludes.DeduplicateAxesFromBase()
	ca.localIncludes.DeduplicateAxesFromBase()
}

// Parse srcs from an arch or OS's props value.
func parseSrcs(ctx android.BazelConversionPathContext, props *BaseCompilerProperties) (bazel.LabelList, bool) {
	anySrcs := false
	// Add srcs-like dependencies such as generated files.
	// First create a LabelList containing these dependencies, then merge the values with srcs.
	generatedSrcsLabelList := android.BazelLabelForModuleDepsExcludes(ctx, props.Generated_sources, props.Exclude_generated_sources)
	if len(props.Generated_sources) > 0 || len(props.Exclude_generated_sources) > 0 {
		anySrcs = true
	}

	allSrcsLabelList := android.BazelLabelForModuleSrcExcludes(ctx, props.Srcs, props.Exclude_srcs)
	if len(props.Srcs) > 0 || len(props.Exclude_srcs) > 0 {
		anySrcs = true
	}
	return bazel.AppendBazelLabelLists(allSrcsLabelList, generatedSrcsLabelList), anySrcs
}

func bp2buildResolveCppStdValue(c_std *string, cpp_std *string, gnu_extensions *bool) (*string, *string) {
	var cStdVal, cppStdVal string
	// If c{,pp}std properties are not specified, don't generate them in the BUILD file.
	// Defaults are handled by the toolchain definition.
	// However, if gnu_extensions is false, then the default gnu-to-c version must be specified.
	if cpp_std != nil {
		cppStdVal = parseCppStd(cpp_std)
	} else if gnu_extensions != nil && !*gnu_extensions {
		cppStdVal = "c++17"
	}
	if c_std != nil {
		cStdVal = parseCStd(c_std)
	} else if gnu_extensions != nil && !*gnu_extensions {
		cStdVal = "c99"
	}

	cStdVal, cppStdVal = maybeReplaceGnuToC(gnu_extensions, cStdVal, cppStdVal)
	var c_std_prop, cpp_std_prop *string
	if cStdVal != "" {
		c_std_prop = &cStdVal
	}
	if cppStdVal != "" {
		cpp_std_prop = &cppStdVal
	}

	return c_std_prop, cpp_std_prop
}

// packageFromLabel extracts package from a fully-qualified or relative Label and whether the label
// is fully-qualified.
// e.g. fully-qualified "//a/b:foo" -> "a/b", true, relative: ":bar" -> ".", false
func packageFromLabel(label string) (string, bool) {
	split := strings.Split(label, ":")
	if len(split) != 2 {
		return "", false
	}
	if split[0] == "" {
		return ".", false
	}
	// remove leading "//"
	return split[0][2:], true
}

// includesFromLabelList extracts relative/absolute includes from a bazel.LabelList>
func includesFromLabelList(labelList bazel.LabelList) (relative, absolute []string) {
	for _, hdr := range labelList.Includes {
		if pkg, hasPkg := packageFromLabel(hdr.Label); hasPkg {
			absolute = append(absolute, pkg)
		} else if pkg != "" {
			relative = append(relative, pkg)
		}
	}
	return relative, absolute
}

// bp2BuildParseCompilerProps returns copts, srcs and hdrs and other attributes.
func bp2BuildParseBaseProps(ctx android.Bp2buildMutatorContext, module *Module) baseAttributes {
	archVariantCompilerProps := module.GetArchVariantProperties(ctx, &BaseCompilerProperties{})
	archVariantLinkerProps := module.GetArchVariantProperties(ctx, &BaseLinkerProperties{})

	var implementationHdrs bazel.LabelListAttribute

	axisToConfigs := map[bazel.ConfigurationAxis]map[string]bool{}
	allAxesAndConfigs := func(cp android.ConfigurationAxisToArchVariantProperties) {
		for axis, configMap := range cp {
			if _, ok := axisToConfigs[axis]; !ok {
				axisToConfigs[axis] = map[string]bool{}
			}
			for config, _ := range configMap {
				axisToConfigs[axis][config] = true
			}
		}
	}
	allAxesAndConfigs(archVariantCompilerProps)
	allAxesAndConfigs(archVariantLinkerProps)

	compilerAttrs := compilerAttributes{}
	linkerAttrs := linkerAttributes{}

	for axis, configs := range axisToConfigs {
		for config, _ := range configs {
			var allHdrs []string
			if baseCompilerProps, ok := archVariantCompilerProps[axis][config].(*BaseCompilerProperties); ok {
				allHdrs = baseCompilerProps.Generated_headers

				(&compilerAttrs).bp2buildForAxisAndConfig(ctx, axis, config, baseCompilerProps)
			}

			var exportHdrs []string

			if baseLinkerProps, ok := archVariantLinkerProps[axis][config].(*BaseLinkerProperties); ok {
				exportHdrs = baseLinkerProps.Export_generated_headers

				(&linkerAttrs).bp2buildForAxisAndConfig(ctx, module.Binary(), axis, config, baseLinkerProps)
			}
			headers := maybePartitionExportedAndImplementationsDeps(ctx, !module.Binary(), allHdrs, exportHdrs, android.BazelLabelForModuleDeps)
			implementationHdrs.SetSelectValue(axis, config, headers.implementation)
			compilerAttrs.hdrs.SetSelectValue(axis, config, headers.export)

			exportIncludes, exportAbsoluteIncludes := includesFromLabelList(headers.export)
			compilerAttrs.includes.Includes.SetSelectValue(axis, config, exportIncludes)
			compilerAttrs.includes.AbsoluteIncludes.SetSelectValue(axis, config, exportAbsoluteIncludes)

			includes, absoluteIncludes := includesFromLabelList(headers.implementation)
			currAbsoluteIncludes := compilerAttrs.absoluteIncludes.SelectValue(axis, config)
			currAbsoluteIncludes = android.FirstUniqueStrings(append(currAbsoluteIncludes, absoluteIncludes...))
			compilerAttrs.absoluteIncludes.SetSelectValue(axis, config, currAbsoluteIncludes)
			currIncludes := compilerAttrs.localIncludes.SelectValue(axis, config)
			currIncludes = android.FirstUniqueStrings(append(currIncludes, includes...))
			compilerAttrs.localIncludes.SetSelectValue(axis, config, currIncludes)
		}
	}

	compilerAttrs.convertStlProps(ctx, module)
	(&linkerAttrs).convertStripProps(ctx, module)

	productVariableProps := android.ProductVariableProperties(ctx)

	(&compilerAttrs).convertProductVariables(ctx, productVariableProps)
	(&linkerAttrs).convertProductVariables(ctx, productVariableProps)

	(&compilerAttrs).finalize(ctx, implementationHdrs)
	(&linkerAttrs).finalize()

	protoDep := bp2buildProto(ctx, module, compilerAttrs.protoSrcs)

	// bp2buildProto will only set wholeStaticLib or implementationWholeStaticLib, but we don't know
	// which. This will add the newly generated proto library to the appropriate attribute and nothing
	// to the other
	(&linkerAttrs).wholeArchiveDeps.Add(protoDep.wholeStaticLib)
	(&linkerAttrs).implementationWholeArchiveDeps.Add(protoDep.implementationWholeStaticLib)

	return baseAttributes{
		compilerAttrs,
		linkerAttrs,
		protoDep.protoDep,
	}
}

// Convenience struct to hold all attributes parsed from linker properties.
type linkerAttributes struct {
	deps                           bazel.LabelListAttribute
	implementationDeps             bazel.LabelListAttribute
	dynamicDeps                    bazel.LabelListAttribute
	implementationDynamicDeps      bazel.LabelListAttribute
	wholeArchiveDeps               bazel.LabelListAttribute
	implementationWholeArchiveDeps bazel.LabelListAttribute
	systemDynamicDeps              bazel.LabelListAttribute

	linkCrt                       bazel.BoolAttribute
	useLibcrt                     bazel.BoolAttribute
	useVersionLib                 bazel.BoolAttribute
	linkopts                      bazel.StringListAttribute
	additionalLinkerInputs        bazel.LabelListAttribute
	stripKeepSymbols              bazel.BoolAttribute
	stripKeepSymbolsAndDebugFrame bazel.BoolAttribute
	stripKeepSymbolsList          bazel.StringListAttribute
	stripAll                      bazel.BoolAttribute
	stripNone                     bazel.BoolAttribute
	features                      bazel.StringListAttribute
}

func (la *linkerAttributes) bp2buildForAxisAndConfig(ctx android.BazelConversionPathContext, isBinary bool, axis bazel.ConfigurationAxis, config string, props *BaseLinkerProperties) {
	// Use a single variable to capture usage of nocrt in arch variants, so there's only 1 error message for this module
	var axisFeatures []string

	// Excludes to parallel Soong:
	// https://cs.android.com/android/platform/superproject/+/master:build/soong/cc/linker.go;l=247-249;drc=088b53577dde6e40085ffd737a1ae96ad82fc4b0
	staticLibs := android.FirstUniqueStrings(props.Static_libs)
	staticDeps := maybePartitionExportedAndImplementationsDepsExcludes(ctx, !isBinary, staticLibs, props.Exclude_static_libs, props.Export_static_lib_headers, bazelLabelForStaticDepsExcludes)

	headerLibs := android.FirstUniqueStrings(props.Header_libs)
	hDeps := maybePartitionExportedAndImplementationsDeps(ctx, !isBinary, headerLibs, props.Export_header_lib_headers, bazelLabelForHeaderDeps)

	(&hDeps.export).Append(staticDeps.export)
	la.deps.SetSelectValue(axis, config, hDeps.export)

	(&hDeps.implementation).Append(staticDeps.implementation)
	la.implementationDeps.SetSelectValue(axis, config, hDeps.implementation)

	wholeStaticLibs := android.FirstUniqueStrings(props.Whole_static_libs)
	la.wholeArchiveDeps.SetSelectValue(axis, config, bazelLabelForWholeDepsExcludes(ctx, wholeStaticLibs, props.Exclude_static_libs))

	systemSharedLibs := props.System_shared_libs
	// systemSharedLibs distinguishes between nil/empty list behavior:
	//    nil -> use default values
	//    empty list -> no values specified
	if len(systemSharedLibs) > 0 {
		systemSharedLibs = android.FirstUniqueStrings(systemSharedLibs)
	}
	la.systemDynamicDeps.SetSelectValue(axis, config, bazelLabelForSharedDeps(ctx, systemSharedLibs))

	sharedLibs := android.FirstUniqueStrings(props.Shared_libs)
	sharedDeps := maybePartitionExportedAndImplementationsDepsExcludes(ctx, !isBinary, sharedLibs, props.Exclude_shared_libs, props.Export_shared_lib_headers, bazelLabelForSharedDepsExcludes)
	la.dynamicDeps.SetSelectValue(axis, config, sharedDeps.export)
	la.implementationDynamicDeps.SetSelectValue(axis, config, sharedDeps.implementation)

	if !BoolDefault(props.Pack_relocations, packRelocationsDefault) {
		axisFeatures = append(axisFeatures, "disable_pack_relocations")
	}

	if Bool(props.Allow_undefined_symbols) {
		axisFeatures = append(axisFeatures, "-no_undefined_symbols")
	}

	var linkerFlags []string
	if len(props.Ldflags) > 0 {
		linkerFlags = append(linkerFlags, props.Ldflags...)
		// binaries remove static flag if -shared is in the linker flags
		if isBinary && android.InList("-shared", linkerFlags) {
			axisFeatures = append(axisFeatures, "-static_flag")
		}
	}
	if props.Version_script != nil {
		label := android.BazelLabelForModuleSrcSingle(ctx, *props.Version_script)
		la.additionalLinkerInputs.SetSelectValue(axis, config, bazel.LabelList{Includes: []bazel.Label{label}})
		linkerFlags = append(linkerFlags, fmt.Sprintf("-Wl,--version-script,$(location %s)", label.Label))
	}
	la.linkopts.SetSelectValue(axis, config, linkerFlags)
	la.useLibcrt.SetSelectValue(axis, config, props.libCrt())

	if axis == bazel.NoConfigAxis {
		la.useVersionLib.SetSelectValue(axis, config, props.Use_version_lib)
	}

	// it's very unlikely for nocrt to be arch variant, so bp2build doesn't support it.
	if props.crt() != nil {
		if axis == bazel.NoConfigAxis {
			la.linkCrt.SetSelectValue(axis, config, props.crt())
		} else if axis == bazel.ArchConfigurationAxis {
			ctx.ModuleErrorf("nocrt is not supported for arch variants")
		}
	}

	if axisFeatures != nil {
		la.features.SetSelectValue(axis, config, axisFeatures)
	}
}

func (la *linkerAttributes) convertStripProps(ctx android.BazelConversionPathContext, module *Module) {
	for axis, configToProps := range module.GetArchVariantProperties(ctx, &StripProperties{}) {
		for config, props := range configToProps {
			if stripProperties, ok := props.(*StripProperties); ok {
				la.stripKeepSymbols.SetSelectValue(axis, config, stripProperties.Strip.Keep_symbols)
				la.stripKeepSymbolsList.SetSelectValue(axis, config, stripProperties.Strip.Keep_symbols_list)
				la.stripKeepSymbolsAndDebugFrame.SetSelectValue(axis, config, stripProperties.Strip.Keep_symbols_and_debug_frame)
				la.stripAll.SetSelectValue(axis, config, stripProperties.Strip.All)
				la.stripNone.SetSelectValue(axis, config, stripProperties.Strip.None)
			}
		}
	}
}

func (la *linkerAttributes) convertProductVariables(ctx android.BazelConversionPathContext, productVariableProps android.ProductConfigProperties) {

	type productVarDep struct {
		// the name of the corresponding excludes field, if one exists
		excludesField string
		// reference to the bazel attribute that should be set for the given product variable config
		attribute *bazel.LabelListAttribute

		depResolutionFunc func(ctx android.BazelConversionPathContext, modules, excludes []string) bazel.LabelList
	}

	productVarToDepFields := map[string]productVarDep{
		// product variables do not support exclude_shared_libs
		"Shared_libs":       {attribute: &la.implementationDynamicDeps, depResolutionFunc: bazelLabelForSharedDepsExcludes},
		"Static_libs":       {"Exclude_static_libs", &la.implementationDeps, bazelLabelForStaticDepsExcludes},
		"Whole_static_libs": {"Exclude_static_libs", &la.wholeArchiveDeps, bazelLabelForWholeDepsExcludes},
	}

	for name, dep := range productVarToDepFields {
		props, exists := productVariableProps[name]
		excludeProps, excludesExists := productVariableProps[dep.excludesField]
		// if neither an include or excludes property exists, then skip it
		if !exists && !excludesExists {
			continue
		}
		// Collect all the configurations that an include or exclude property exists for.
		// We want to iterate all configurations rather than either the include or exclude because, for a
		// particular configuration, we may have either only an include or an exclude to handle.
		productConfigProps := make(map[android.ProductConfigProperty]bool, len(props)+len(excludeProps))
		for p := range props {
			productConfigProps[p] = true
		}
		for p := range excludeProps {
			productConfigProps[p] = true
		}

		for productConfigProp := range productConfigProps {
			prop, includesExists := props[productConfigProp]
			excludesProp, excludesExists := excludeProps[productConfigProp]
			var includes, excludes []string
			var ok bool
			// if there was no includes/excludes property, casting fails and that's expected
			if includes, ok = prop.([]string); includesExists && !ok {
				ctx.ModuleErrorf("Could not convert product variable %s property", name)
			}
			if excludes, ok = excludesProp.([]string); excludesExists && !ok {
				ctx.ModuleErrorf("Could not convert product variable %s property", dep.excludesField)
			}

			dep.attribute.EmitEmptyList = productConfigProp.AlwaysEmit()
			dep.attribute.SetSelectValue(
				productConfigProp.ConfigurationAxis(),
				productConfigProp.SelectKey(),
				dep.depResolutionFunc(ctx, android.FirstUniqueStrings(includes), excludes),
			)
		}
	}
}

func (la *linkerAttributes) finalize() {
	la.deps.ResolveExcludes()
	la.implementationDeps.ResolveExcludes()
	la.dynamicDeps.ResolveExcludes()
	la.implementationDynamicDeps.ResolveExcludes()
	la.wholeArchiveDeps.ResolveExcludes()
	la.systemDynamicDeps.ForceSpecifyEmptyList = true
}

// Relativize a list of root-relative paths with respect to the module's
// directory.
//
// include_dirs Soong prop are root-relative (b/183742505), but
// local_include_dirs, export_include_dirs and export_system_include_dirs are
// module dir relative. This function makes a list of paths entirely module dir
// relative.
//
// For the `include` attribute, Bazel wants the paths to be relative to the
// module.
func bp2BuildMakePathsRelativeToModule(ctx android.BazelConversionPathContext, paths []string) []string {
	var relativePaths []string
	for _, path := range paths {
		// Semantics of filepath.Rel: join(ModuleDir, rel(ModuleDir, path)) == path
		relativePath, err := filepath.Rel(ctx.ModuleDir(), path)
		if err != nil {
			panic(err)
		}
		relativePaths = append(relativePaths, relativePath)
	}
	return relativePaths
}

// BazelIncludes contains information about -I and -isystem paths from a module converted to Bazel
// attributes.
type BazelIncludes struct {
	AbsoluteIncludes bazel.StringListAttribute
	Includes         bazel.StringListAttribute
	SystemIncludes   bazel.StringListAttribute
}

func bp2BuildParseExportedIncludes(ctx android.BazelConversionPathContext, module *Module, existingIncludes BazelIncludes) BazelIncludes {
	libraryDecorator := module.linker.(*libraryDecorator)
	return bp2BuildParseExportedIncludesHelper(ctx, module, libraryDecorator, &existingIncludes)
}

// Bp2buildParseExportedIncludesForPrebuiltLibrary returns a BazelIncludes with Bazel-ified values
// to export includes from the underlying module's properties.
func Bp2BuildParseExportedIncludesForPrebuiltLibrary(ctx android.BazelConversionPathContext, module *Module) BazelIncludes {
	prebuiltLibraryLinker := module.linker.(*prebuiltLibraryLinker)
	libraryDecorator := prebuiltLibraryLinker.libraryDecorator
	return bp2BuildParseExportedIncludesHelper(ctx, module, libraryDecorator, nil)
}

// bp2BuildParseExportedIncludes creates a string list attribute contains the
// exported included directories of a module.
func bp2BuildParseExportedIncludesHelper(ctx android.BazelConversionPathContext, module *Module, libraryDecorator *libraryDecorator, includes *BazelIncludes) BazelIncludes {
	var exported BazelIncludes
	if includes != nil {
		exported = *includes
	} else {
		exported = BazelIncludes{}
	}
	for axis, configToProps := range module.GetArchVariantProperties(ctx, &FlagExporterProperties{}) {
		for config, props := range configToProps {
			if flagExporterProperties, ok := props.(*FlagExporterProperties); ok {
				if len(flagExporterProperties.Export_include_dirs) > 0 {
					exported.Includes.SetSelectValue(axis, config, android.FirstUniqueStrings(append(exported.Includes.SelectValue(axis, config), flagExporterProperties.Export_include_dirs...)))
				}
				if len(flagExporterProperties.Export_system_include_dirs) > 0 {
					exported.SystemIncludes.SetSelectValue(axis, config, android.FirstUniqueStrings(append(exported.SystemIncludes.SelectValue(axis, config), flagExporterProperties.Export_system_include_dirs...)))
				}
			}
		}
	}
	exported.AbsoluteIncludes.DeduplicateAxesFromBase()
	exported.Includes.DeduplicateAxesFromBase()
	exported.SystemIncludes.DeduplicateAxesFromBase()

	return exported
}

func bazelLabelForStaticModule(ctx android.BazelConversionPathContext, m blueprint.Module) string {
	label := android.BazelModuleLabel(ctx, m)
	if aModule, ok := m.(android.Module); ok {
		if ctx.OtherModuleType(aModule) == "cc_library" && !android.GenerateCcLibraryStaticOnly(m.Name()) {
			label += "_bp2build_cc_library_static"
		}
	}
	return label
}

func bazelLabelForSharedModule(ctx android.BazelConversionPathContext, m blueprint.Module) string {
	// cc_library, at it's root name, propagates the shared library, which depends on the static
	// library.
	return android.BazelModuleLabel(ctx, m)
}

func bazelLabelForStaticWholeModuleDeps(ctx android.BazelConversionPathContext, m blueprint.Module) string {
	label := bazelLabelForStaticModule(ctx, m)
	if aModule, ok := m.(android.Module); ok {
		if android.IsModulePrebuilt(aModule) {
			label += "_alwayslink"
		}
	}
	return label
}

func bazelLabelForWholeDeps(ctx android.BazelConversionPathContext, modules []string) bazel.LabelList {
	return android.BazelLabelForModuleDepsWithFn(ctx, modules, bazelLabelForStaticWholeModuleDeps)
}

func bazelLabelForWholeDepsExcludes(ctx android.BazelConversionPathContext, modules, excludes []string) bazel.LabelList {
	return android.BazelLabelForModuleDepsExcludesWithFn(ctx, modules, excludes, bazelLabelForStaticWholeModuleDeps)
}

func bazelLabelForStaticDepsExcludes(ctx android.BazelConversionPathContext, modules, excludes []string) bazel.LabelList {
	return android.BazelLabelForModuleDepsExcludesWithFn(ctx, modules, excludes, bazelLabelForStaticModule)
}

func bazelLabelForStaticDeps(ctx android.BazelConversionPathContext, modules []string) bazel.LabelList {
	return android.BazelLabelForModuleDepsWithFn(ctx, modules, bazelLabelForStaticModule)
}

func bazelLabelForSharedDeps(ctx android.BazelConversionPathContext, modules []string) bazel.LabelList {
	return android.BazelLabelForModuleDepsWithFn(ctx, modules, bazelLabelForSharedModule)
}

func bazelLabelForHeaderDeps(ctx android.BazelConversionPathContext, modules []string) bazel.LabelList {
	// This is not elegant, but bp2build's shared library targets only propagate
	// their header information as part of the normal C++ provider.
	return bazelLabelForSharedDeps(ctx, modules)
}

func bazelLabelForSharedDepsExcludes(ctx android.BazelConversionPathContext, modules, excludes []string) bazel.LabelList {
	return android.BazelLabelForModuleDepsExcludesWithFn(ctx, modules, excludes, bazelLabelForSharedModule)
}

type binaryLinkerAttrs struct {
	Linkshared *bool
}

func bp2buildBinaryLinkerProps(ctx android.BazelConversionPathContext, m *Module) binaryLinkerAttrs {
	attrs := binaryLinkerAttrs{}
	archVariantProps := m.GetArchVariantProperties(ctx, &BinaryLinkerProperties{})
	for axis, configToProps := range archVariantProps {
		for _, p := range configToProps {
			props := p.(*BinaryLinkerProperties)
			staticExecutable := props.Static_executable
			if axis == bazel.NoConfigAxis {
				if linkBinaryShared := !proptools.Bool(staticExecutable); !linkBinaryShared {
					attrs.Linkshared = &linkBinaryShared
				}
			} else if staticExecutable != nil {
				// TODO(b/202876379): Static_executable is arch-variant; however, linkshared is a
				// nonconfigurable attribute. Only 4 AOSP modules use this feature, defer handling
				ctx.ModuleErrorf("bp2build cannot migrate a module with arch/target-specific static_executable values")
			}
		}
	}

	return attrs
}