build/bazel/bazel_inputs.gni - fuchsia - Git at Google

 # Copyright 2022 The Fuchsia Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.

 # A set of GN templates to expose Ninja-generated output files as inputs
 # to bazel_action() targets. The latter run a `bazel build` command in
 # the Bazel workspace setup by the platform build, which cannot access
 # the Ninja output directory directly.
 #
 # A bazel_input_xxx() target defines a mapping from Ninja-generated outputs
 # to files and Bazel filegroup() targets defined in the special repository
 # named @legacy_ninja_build_outputs.
 #
 # For example, to expose the files generated by an action `foo` as a
 # filegroup() with Bazel label @legacy_ninja_build_outputs//:foo_files, one
 # can use the following definition:
 #
 # ```gn
 #   # Expose all outputs generated by :foo in Bazel.
 #   bazel_input_resource("foo_files") {
 #    deps = [ ":foo" ]
 #    sources = get_target_outputs(":foo")
 #    outputs = [ "{{source_file_part}}" ]
 #  }
 #
 # IMPORTANT: Simply defining a bazel_input_xxx() target is NOT ENOUGH, it must
 # ALSO be part of the transitive dependencies listed from one of the lists
 # defined in //build/bazel/legacy_ninja_build_outputs.gni
 #
 # There is no way to enforce that with GN at the moment.
 #

 # Expose a set of Ninja output files as a corresponding Bazel filegroup()
 # of prebuilt input sources for the Bazel build.
 #
 # This template works like copy() or resource(). Consider using
 # bazel_input_resource_tree() if you have multiple source files with
 # non-trivial outputs paths.
 #
 # ```gn
 #   # Expose all outputs generated by :foo in Bazel.
 #   bazel_input_resource("foo_files") {
 #    deps = [ ":foo" ]
 #    sources = get_target_outputs(":foo")
 #    outputs = [ "{{source_file_part}}" ]
 #  }
 #
 #  ...
 #
 #  Make sure this is reachable from the transitive dependencies listed in
 #  //build/bazel/legacy_ninja_build_outputs.gni, e.g.:
 #
 # ```
 #  gn_labels_for_bazel_inputs += [ "//src/foo:foo_files" ]
 # ```
 #
 # Assuming that :foo generates the following files:
 #
 #    out/default/gen/src/foo/foo.h
 #    out/default/gen/src/foo/foo.cc
 #
 # Then this will generate something like that @legacy_ninja_build_outputs/BUILD.bazel:
 #
 # ```bazel
 #  filegroup("foo_files") {
 #      srcs = [
 #        "foo.h",
 #        "foo.cc",
 #      ]
 #  )
 # ```
 #
 # After creating the symlinks as:
 #
 #  $BAZEL_TOPDIR/output_base/external/legacy_ninja_build_outputs/
 #    foo.h --> ../../../../../src/foo/foo.h
 #    foo.cc --> ../../../../../src/foo/foo.cc
 #
 # Arguments:
 #   name: (optional)
 #     Bazel filegroup name for the set of files covered by this target.
 #     If not specified, defaults to target_name. Note that the filegroup()
 #     will be part of the top-level BUILD.bazel file generated by the
 #     build)_inputs_workspace() dependent. This name cannot contain a
 #     directory separator or colon.
 #     Type: string
 #
 #   sources
 #     Required: List of output files that become sources in the Bazel
 #     workspace. Technically works with Ninja source files as well, but these
 #     are already exposed to Bazel by default, and don't need to be
 #     listed in a bazel_input_resource() target. See copy() for details.
 #     Type: list(file)
 #
 #   outputs
 #     Required: List of one runtime path.  This must be a relative path (no
 #     leading `/`).  It can use placeholders based on $sources; see copy()
 #     and `gn help source_expansion`.
 #     Type: list(path)
 #
 #   deps
 #     Optional: Targets that produce $sources.  Any files listed in
 #     $sources that are produced by the build should be produced by a
 #     target listed here.
 #     Type: list(label)
 #
 template("bazel_input_resource") {
   _name = target_name
   if (defined(invoker.name)) {
     _name = invoker.name
     assert(string_replace(_name, "/", "") == _name,
            "name cannot contain directory separators: $_name")
     assert(string_replace(_name, ":", "") == _name,
            "name cannot contain colon: $_name")
   }

   _sources = rebase_path(invoker.sources, root_build_dir)
   _dest = process_file_template(invoker.sources, invoker.outputs)

   foreach(dst_path, _dest) {
     assert(
         rebase_path(dst_path, "//") != dst_path,
         "`outputs` in bazel_input_resource() cannot start with /: ${dst_path}")
   }

   group(target_name) {
     forward_variables_from(invoker,
                            "*",
                            [
                              "metadata",
                              "name",
                              "outputs",
                              "sources",
                            ])

     metadata = {
       # Used by bazel_inputs_manifest() template.
       # See its documentation for the metadata schema.
       bazel_inputs = [
         {
           name = _name
           sources = _sources
           destinations = _dest
           gn_label = get_label_info(":$target_name", "label_with_toolchain")
         },
       ]
       bazel_inputs_barrier = []
     }
   }
 }

 # bazel_input_resource_tree() is similar to bazel_input_resource() but
 # makes it easy to replicate a tree of sources files, relative to a given
 # sources path prefix, to a given destination directory.
 #
 # For example:
 #
 #      bazel_input_resource_tree("my-resources") {
 #        sources_root = "res"
 #        sources = [
 #          foo.resource",
 #          bar/bar-1.resource",
 #        ]
 #        dest_dir = "data/resources"
 #      }
 #
 # Will declare the following symlinks:
 #
 #   $BAZEL_TOPDIR/legacy_ninja_build_outputs/
 #     data/resources/
 #       foo.resource ---> .../res/foo.resource
 #       bar/bar.resource ---> .../res/bar/bar.resource
 #
 # And will generate the following Bazel fragment:
 #
 #   filegroup("my-resources") {
 #       srcs = [
 #           "data/resources/foo.resource",
 #           "data/resources/bar/bar.resource",
 #       ]
 #   )
 #
 # This is difficult to do with resource() because GN source expansion
 # cannot preserve the original sources input paths.
 #
 # This template is useful to avoid calling bazel_input_resource() multiple
 # times in a loop when dealing with resource files laid out into different
 # sub-directories. Note that the files cannot be renamed though!
 #
 # Parameters
 #   name: (optional)
 #     Bazel filegroup name for the set of files covered by this target.
 #     If not specified, defaults to target_name. Note that the filegroup()
 #     will be part of the top-level BUILD.bazel file generated by the
 #     build)_inputs_workspace() dependent. This name cannot contain a
 #     directory separator or colon.
 #     Type: string
 #
 #   source_root
 #     Optional: A path prefix that is prepended to all items in the 'sources'
 #     list. If not specified, the current target's directory is used.
 #     Type: string(path)
 #
 #   sources
 #     Required: List of files in the source tree or build that will be
 #     installed. Each 'file' item in this list is exposed as
 #     '$dest_dir/$file', as a symlink to  '$sources_root/$file'.
 #     Note that unlike bazel_input_resource(), there is no way to transform
 #     or expand source paths.
 #     Type: list(file)
 #
 #   dest_dir
 #     Required: Destination path where all sources are exposed.
 #     Cannot start with a "/". Use an empty string to expose files directly
 #     to the workspace's top-level directory.
 #     Type: string(path)
 #
 #   deps
 #     Optional: Targets that produce $sources.  Any files listed in
 #     $sources that are produced by the build should be produced by a
 #     target listed here.
 #     Type: list(label)
 #
 template("bazel_input_resource_tree") {
   _name = target_name
   if (defined(invoker.name)) {
     _name = invoker.name
     assert(string_replace(_name, "/", "") == _name,
            "name cannot contain directory separators: $_name")
     assert(string_replace(_name, ":", "") == _name,
            "name cannot contain colon: $_name")
   }
   assert(defined(invoker.sources), "sources is required")
   assert(defined(invoker.dest_dir), "dest_dir is required")
   dest_dir = invoker.dest_dir
   if (dest_dir != "") {
     assert(rebase_path(dest_dir, "foo") != dest_dir,
            "dest_dir cannot start with /: $dest_dir")
     assert(dest_dir != "." && dest_dir != ".." &&
                string_replace(dest_dir, "./", "") == dest_dir,
            "dest_dir cannot contain . or .. path elements: $dest_dir")

     # Add trailing directory separator.
     dest_dir = string_replace(dest_dir + "//", "//", "/")
   }

   if (defined(invoker.sources_root)) {
     assert(invoker.sources_root != "", "sources_root cannot be empty!")
     sources_prefix = invoker.sources_root

     # Append trailing separator if needed
     if (string_replace(sources_prefix + "###", "/###", "") ==
         sources_prefix + "###") {
       sources_prefix += "/"
     }
   } else {
     sources_prefix = ""
   }

   _name = target_name
   if (defined(invoker.name)) {
     _name = invoker.name
     assert(string_replace(_name, "/", "") == _name,
            "name cannot contain directory separators: $_name")
     assert(string_replace(_name, ":", "") == _name,
            "name cannot contain colon: $_name")
   }

   _sources = []
   _dest = []
   foreach(_source, invoker.sources) {
     _sources += [ dest_dir + _source ]
     _dest += [ rebase_path(sources_prefix + _source, root_build_dir) ]
   }

   group(target_name) {
     forward_variables_from(invoker,
                            "*",
                            [
                              "dest_dir",
                              "metadata",
                              "sources",
                              "sources_root",
                            ])
     metadata = {
       # Used by bazel_inputs_manifest() template.
       bazel_inputs = [
         {
           name = _name
           sources = _sources
           destinations = _dest
           gn_label = get_label_info(":$target_name", "label_with_toolchain")
         },
       ]
       bazel_inputs_barrier = []
     }
   }
 }

 # bazel_input_resource_directory() is used to expose the content of a Ninja
 # output directory as a Bazel input filegroup. Instead of passing a list of
 # source files, `source_root` source point to a directory whose content will
 # be symlinks into a bazel_build_inputs_workspace().
 #
 # IMPORTANT: This is not hermetic, and can lead to incorrect results during
 # incremental builds, unless the directory's content is always cleared
 # before the Ninja action that generates its content is run.
 #
 # For example:
 #
 #    bazel_input_resource_directory"my-generated-resources") {
 #      source_dir = get_label_info(":resource-generator", "target_gen_dir")
 #      dest_dir = "data/resources"
 #      deps = [ ¨:resource-generator" ]
 #    }
 #
 # Parameters
 #   name: (optional)
 #     Bazel filegroup name for the set of files covered by this target.
 #     If not specified, defaults to target_name. Note that the filegroup()
 #     will be part of the top-level BUILD.bazel file generated by the
 #     build)_inputs_workspace() dependent. This name cannot contain a
 #     directory separator or colon.
 #     Type: string
 #
 #   source_dir
 #     Required: GN path to the source directory that contains all outputs
 #     files to be exposed as a Bazel filegroup().
 #     Type: string(path)
 #
 #   dest_dir
 #     Required: Destination path where all sources are exposed.
 #     Cannot start with a "/". Use an empty string to expose files directly
 #     to the workspace's top-level directory.
 #     Type: string(path)
 #
 #   deps
 #     Optional: Targets that produce $sources.  Any files listed in
 #     $sources that are produced by the build should be produced by a
 #     target listed here.
 #     Type: list(label)
 #
 template("bazel_input_resource_directory") {
   _name = target_name
   if (defined(invoker.name)) {
     _name = invoker.name
     assert(string_replace(_name, "/", "") == _name,
            "name cannot contain directory separators: $_name")
     assert(string_replace(_name, ":", "") == _name,
            "name cannot contain colon: $_name")
   }
   assert(defined(invoker.dest_dir), "dest_dir is required")
   dest_dir = invoker.dest_dir
   if (dest_dir != "") {
     assert(rebase_path(dest_dir, "foo") != dest_dir,
            "dest_dir cannot start with /: $dest_dir")
     assert(dest_dir != "." && dest_dir != ".." &&
                string_replace(dest_dir, "./", "") == dest_dir,
            "dest_dir cannot contain . or .. path elements: $dest_dir")

     # Add trailing directory separator.
     dest_dir = string_replace(dest_dir + "//", "//", "/")
   }

   group(target_name) {
     forward_variables_from(invoker,
                            [
                              "deps",
                              "testonly",
                              "visibility",
                            ])
     metadata = {
       # Used by bazel_inputs_manifest() template.
       bazel_inputs = [
         {
           name = _name
           source_dir = rebase_path(invoker.source_dir, root_build_dir)
           dest_dir = dest_dir
           gn_label = get_label_info(":$target_name", "label_with_toolchain")
         },
       ]
       bazel_inputs_barrier = []
     }
   }
 }

 # Generate a manifest file describing the content of the Bazel inputs
 # repository that will be used by the Bazel workspace to read Ninja outputs
 # as sources / prebuilts.
 #
 # Args:
 #   output:
 #     Path to generated manifest file.
 #
 #   inputs_deps:
 #     A list of targets, all transitive dependencies which are bazel_input_xxx()
 #     target will generate one entry in the manifest.
 #
 template("generate_bazel_inputs_manifest") {
   # Generate a single manifest file that collects all bazel_input_xxx()
   # resources. Each metadata entry is a scope that describes a single
   # Bazel filegroup() target that will appear at the top of the
   # auto-generated workspace.
   #
   # There are two types of entries:
   #
   # ## REGULAR ENTRIES
   #
   #   These entries expose an explicit list of files, they look like:
   #
   #     name: (required)
   #        Bazel filegroup name.
   #        Type: string
   #
   #     destinations: (required)
   #        List of input files, relative to the top of the generated workspace.
   #        Each one will appear in the `srcs` list of the corresponding
   #        filegroup.
   #
   #     sources: (required)
   #        List of source files for the filegroup. Must have the same
   #        size as the `destinations` list.
   #        Type: list of paths relative to the root_build_dir
   #
   #     gn_label:
   #        GN label of target that defines this entry.
   #        Type: GN label string
   #
   #   They should generate Bazel targets that look like:
   #
   #     filegroup(
   #        name = "<name>",
   #        srcs = [
   #            <destination_1>,
   #            <destination_2>,
   #            ...
   #        ],
   #     )
   #
   #   Where <destination_N> is the N-th entry in `destinations`, and will be
   #   the path to a symlink (in the repository) to the corresponding
   #   <sources_N> file.
   #
   # ## DIRECTORY ENTRIES
   #
   #   These entries expose all files under a given output directory as
   #   a single filegroup() using the glob() function. IMPORTANT: For
   #   correctness, only use these when it is 100% sure that the content
   #   of the source directory is re-created properly during incremental
   #   builds. These look like:
   #
   #     name: (required)
   #        Bazel filegroup name.
   #        Type: string
   #
   #     source_dir: (required)
   #        A source directory path, relative to the Ninja build output
   #        directory, which will contain all input files for the Bazel
   #        filegroup().
   #
   #     dest_dir: (required)
   #        A directory prefix for all input files, relative to the top of
   #        the generated workspace. This will be a symlink to source_dir,
   #        and the filegroup() will use a glob(["<dest_dir>/*"]) call to get all
   #        files in it.
   #
   #     gn_label: (optional)
   #        GN label of target that defines this entry.
   #        Type: GN label string
   #
   #   They should generate Bazel targets that look like:
   #
   #     filegroup(
   #         name = "<name>",
   #         srcs = glob(["<dest_dir>/**]),
   #     )
   #
   #   Where <dest_dir> is a repository symlink that points to source_dir.
   #
   generated_file(target_name) {
     forward_variables_from(invoker, [ "testonly" ])
     outputs = [ invoker.output ]
     data_keys = [ "bazel_inputs" ]
     walk_keys = [ "bazel_inputs_barrier" ]
     deps = invoker.inputs_deps
     output_conversion = "json"
   }
 }
	# Copyright 2022 The Fuchsia Authors. All rights reserved.
	# Use of this source code is governed by a BSD-style license that can be
	# found in the LICENSE file.

	# A set of GN templates to expose Ninja-generated output files as inputs
	# to bazel_action() targets. The latter run a `bazel build` command in
	# the Bazel workspace setup by the platform build, which cannot access
	# the Ninja output directory directly.
	#
	# A bazel_input_xxx() target defines a mapping from Ninja-generated outputs
	# to files and Bazel filegroup() targets defined in the special repository
	# named @legacy_ninja_build_outputs.
	#
	# For example, to expose the files generated by an action `foo` as a
	# filegroup() with Bazel label @legacy_ninja_build_outputs//:foo_files, one
	# can use the following definition:
	#
	# ```gn
	# # Expose all outputs generated by :foo in Bazel.
	# bazel_input_resource("foo_files") {
	# deps = [ ":foo" ]
	# sources = get_target_outputs(":foo")
	# outputs = [ "{{source_file_part}}" ]
	# }
	#
	# IMPORTANT: Simply defining a bazel_input_xxx() target is NOT ENOUGH, it must
	# ALSO be part of the transitive dependencies listed from one of the lists
	# defined in //build/bazel/legacy_ninja_build_outputs.gni
	#
	# There is no way to enforce that with GN at the moment.
	#

	# Expose a set of Ninja output files as a corresponding Bazel filegroup()
	# of prebuilt input sources for the Bazel build.
	#
	# This template works like copy() or resource(). Consider using
	# bazel_input_resource_tree() if you have multiple source files with
	# non-trivial outputs paths.
	#
	# ```gn
	# # Expose all outputs generated by :foo in Bazel.
	# bazel_input_resource("foo_files") {
	# deps = [ ":foo" ]
	# sources = get_target_outputs(":foo")
	# outputs = [ "{{source_file_part}}" ]
	# }
	#
	# ...
	#
	# Make sure this is reachable from the transitive dependencies listed in
	# //build/bazel/legacy_ninja_build_outputs.gni, e.g.:
	#
	# ```
	# gn_labels_for_bazel_inputs += [ "//src/foo:foo_files" ]
	# ```
	#
	# Assuming that :foo generates the following files:
	#
	# out/default/gen/src/foo/foo.h
	# out/default/gen/src/foo/foo.cc
	#
	# Then this will generate something like that @legacy_ninja_build_outputs/BUILD.bazel:
	#
	# ```bazel
	# filegroup("foo_files") {
	# srcs = [
	# "foo.h",
	# "foo.cc",
	# ]
	# )
	# ```
	#
	# After creating the symlinks as:
	#
	# $BAZEL_TOPDIR/output_base/external/legacy_ninja_build_outputs/
	# foo.h --> ../../../../../src/foo/foo.h
	# foo.cc --> ../../../../../src/foo/foo.cc
	#
	# Arguments:
	# name: (optional)
	# Bazel filegroup name for the set of files covered by this target.
	# If not specified, defaults to target_name. Note that the filegroup()
	# will be part of the top-level BUILD.bazel file generated by the
	# build)_inputs_workspace() dependent. This name cannot contain a
	# directory separator or colon.
	# Type: string
	#
	# sources
	# Required: List of output files that become sources in the Bazel
	# workspace. Technically works with Ninja source files as well, but these
	# are already exposed to Bazel by default, and don't need to be
	# listed in a bazel_input_resource() target. See copy() for details.
	# Type: list(file)
	#
	# outputs
	# Required: List of one runtime path. This must be a relative path (no
	# leading `/`). It can use placeholders based on $sources; see copy()
	# and `gn help source_expansion`.
	# Type: list(path)
	#
	# deps
	# Optional: Targets that produce $sources. Any files listed in
	# $sources that are produced by the build should be produced by a
	# target listed here.
	# Type: list(label)
	#
	template("bazel_input_resource") {
	_name = target_name
	if (defined(invoker.name)) {
	_name = invoker.name
	assert(string_replace(_name, "/", "") == _name,
	"name cannot contain directory separators: $_name")
	assert(string_replace(_name, ":", "") == _name,
	"name cannot contain colon: $_name")
	}

	_sources = rebase_path(invoker.sources, root_build_dir)
	_dest = process_file_template(invoker.sources, invoker.outputs)

	foreach(dst_path, _dest) {
	assert(
	rebase_path(dst_path, "//") != dst_path,
	"`outputs` in bazel_input_resource() cannot start with /: ${dst_path}")
	}

	group(target_name) {
	forward_variables_from(invoker,
	"*",
	[
	"metadata",
	"name",
	"outputs",
	"sources",
	])

	metadata = {
	# Used by bazel_inputs_manifest() template.
	# See its documentation for the metadata schema.
	bazel_inputs = [
	{
	name = _name
	sources = _sources
	destinations = _dest
	gn_label = get_label_info(":$target_name", "label_with_toolchain")
	},
	]
	bazel_inputs_barrier = []
	}
	}
	}

	# bazel_input_resource_tree() is similar to bazel_input_resource() but
	# makes it easy to replicate a tree of sources files, relative to a given
	# sources path prefix, to a given destination directory.
	#
	# For example:
	#
	# bazel_input_resource_tree("my-resources") {
	# sources_root = "res"
	# sources = [
	# foo.resource",
	# bar/bar-1.resource",
	# ]
	# dest_dir = "data/resources"
	# }
	#
	# Will declare the following symlinks:
	#
	# $BAZEL_TOPDIR/legacy_ninja_build_outputs/
	# data/resources/
	# foo.resource ---> .../res/foo.resource
	# bar/bar.resource ---> .../res/bar/bar.resource
	#
	# And will generate the following Bazel fragment:
	#
	# filegroup("my-resources") {
	# srcs = [
	# "data/resources/foo.resource",
	# "data/resources/bar/bar.resource",
	# ]
	# )
	#
	# This is difficult to do with resource() because GN source expansion
	# cannot preserve the original sources input paths.
	#
	# This template is useful to avoid calling bazel_input_resource() multiple
	# times in a loop when dealing with resource files laid out into different
	# sub-directories. Note that the files cannot be renamed though!
	#
	# Parameters
	# name: (optional)
	# Bazel filegroup name for the set of files covered by this target.
	# If not specified, defaults to target_name. Note that the filegroup()
	# will be part of the top-level BUILD.bazel file generated by the
	# build)_inputs_workspace() dependent. This name cannot contain a
	# directory separator or colon.
	# Type: string
	#
	# source_root
	# Optional: A path prefix that is prepended to all items in the 'sources'
	# list. If not specified, the current target's directory is used.
	# Type: string(path)
	#
	# sources
	# Required: List of files in the source tree or build that will be
	# installed. Each 'file' item in this list is exposed as
	# '$dest_dir/$file', as a symlink to '$sources_root/$file'.
	# Note that unlike bazel_input_resource(), there is no way to transform
	# or expand source paths.
	# Type: list(file)
	#
	# dest_dir
	# Required: Destination path where all sources are exposed.
	# Cannot start with a "/". Use an empty string to expose files directly
	# to the workspace's top-level directory.
	# Type: string(path)
	#
	# deps
	# Optional: Targets that produce $sources. Any files listed in
	# $sources that are produced by the build should be produced by a
	# target listed here.
	# Type: list(label)
	#
	template("bazel_input_resource_tree") {
	_name = target_name
	if (defined(invoker.name)) {
	_name = invoker.name
	assert(string_replace(_name, "/", "") == _name,
	"name cannot contain directory separators: $_name")
	assert(string_replace(_name, ":", "") == _name,
	"name cannot contain colon: $_name")
	}
	assert(defined(invoker.sources), "sources is required")
	assert(defined(invoker.dest_dir), "dest_dir is required")
	dest_dir = invoker.dest_dir
	if (dest_dir != "") {
	assert(rebase_path(dest_dir, "foo") != dest_dir,
	"dest_dir cannot start with /: $dest_dir")
	assert(dest_dir != "." && dest_dir != ".." &&
	string_replace(dest_dir, "./", "") == dest_dir,
	"dest_dir cannot contain . or .. path elements: $dest_dir")

	# Add trailing directory separator.
	dest_dir = string_replace(dest_dir + "//", "//", "/")
	}

	if (defined(invoker.sources_root)) {
	assert(invoker.sources_root != "", "sources_root cannot be empty!")
	sources_prefix = invoker.sources_root

	# Append trailing separator if needed
	if (string_replace(sources_prefix + "###", "/###", "") ==
	sources_prefix + "###") {
	sources_prefix += "/"
	}
	} else {
	sources_prefix = ""
	}

	_name = target_name
	if (defined(invoker.name)) {
	_name = invoker.name
	assert(string_replace(_name, "/", "") == _name,
	"name cannot contain directory separators: $_name")
	assert(string_replace(_name, ":", "") == _name,
	"name cannot contain colon: $_name")
	}

	_sources = []
	_dest = []
	foreach(_source, invoker.sources) {
	_sources += [ dest_dir + _source ]
	_dest += [ rebase_path(sources_prefix + _source, root_build_dir) ]
	}

	group(target_name) {
	forward_variables_from(invoker,
	"*",
	[
	"dest_dir",
	"metadata",
	"sources",
	"sources_root",
	])
	metadata = {
	# Used by bazel_inputs_manifest() template.
	bazel_inputs = [
	{
	name = _name
	sources = _sources
	destinations = _dest
	gn_label = get_label_info(":$target_name", "label_with_toolchain")
	},
	]
	bazel_inputs_barrier = []
	}
	}
	}

	# bazel_input_resource_directory() is used to expose the content of a Ninja
	# output directory as a Bazel input filegroup. Instead of passing a list of
	# source files, `source_root` source point to a directory whose content will
	# be symlinks into a bazel_build_inputs_workspace().
	#
	# IMPORTANT: This is not hermetic, and can lead to incorrect results during
	# incremental builds, unless the directory's content is always cleared
	# before the Ninja action that generates its content is run.
	#
	# For example:
	#
	# bazel_input_resource_directory"my-generated-resources") {
	# source_dir = get_label_info(":resource-generator", "target_gen_dir")
	# dest_dir = "data/resources"
	# deps = [ ¨:resource-generator" ]
	# }
	#
	# Parameters
	# name: (optional)
	# Bazel filegroup name for the set of files covered by this target.
	# If not specified, defaults to target_name. Note that the filegroup()
	# will be part of the top-level BUILD.bazel file generated by the
	# build)_inputs_workspace() dependent. This name cannot contain a
	# directory separator or colon.
	# Type: string
	#
	# source_dir
	# Required: GN path to the source directory that contains all outputs
	# files to be exposed as a Bazel filegroup().
	# Type: string(path)
	#
	# dest_dir
	# Required: Destination path where all sources are exposed.
	# Cannot start with a "/". Use an empty string to expose files directly
	# to the workspace's top-level directory.
	# Type: string(path)
	#
	# deps
	# Optional: Targets that produce $sources. Any files listed in
	# $sources that are produced by the build should be produced by a
	# target listed here.
	# Type: list(label)
	#
	template("bazel_input_resource_directory") {
	_name = target_name
	if (defined(invoker.name)) {
	_name = invoker.name
	assert(string_replace(_name, "/", "") == _name,
	"name cannot contain directory separators: $_name")
	assert(string_replace(_name, ":", "") == _name,
	"name cannot contain colon: $_name")
	}
	assert(defined(invoker.dest_dir), "dest_dir is required")
	dest_dir = invoker.dest_dir
	if (dest_dir != "") {
	assert(rebase_path(dest_dir, "foo") != dest_dir,
	"dest_dir cannot start with /: $dest_dir")
	assert(dest_dir != "." && dest_dir != ".." &&
	string_replace(dest_dir, "./", "") == dest_dir,
	"dest_dir cannot contain . or .. path elements: $dest_dir")

	# Add trailing directory separator.
	dest_dir = string_replace(dest_dir + "//", "//", "/")
	}

	group(target_name) {
	forward_variables_from(invoker,
	[
	"deps",
	"testonly",
	"visibility",
	])
	metadata = {
	# Used by bazel_inputs_manifest() template.
	bazel_inputs = [
	{
	name = _name
	source_dir = rebase_path(invoker.source_dir, root_build_dir)
	dest_dir = dest_dir
	gn_label = get_label_info(":$target_name", "label_with_toolchain")
	},
	]
	bazel_inputs_barrier = []
	}
	}
	}

	# Generate a manifest file describing the content of the Bazel inputs
	# repository that will be used by the Bazel workspace to read Ninja outputs
	# as sources / prebuilts.
	#
	# Args:
	# output:
	# Path to generated manifest file.
	#
	# inputs_deps:
	# A list of targets, all transitive dependencies which are bazel_input_xxx()
	# target will generate one entry in the manifest.
	#
	template("generate_bazel_inputs_manifest") {
	# Generate a single manifest file that collects all bazel_input_xxx()
	# resources. Each metadata entry is a scope that describes a single
	# Bazel filegroup() target that will appear at the top of the
	# auto-generated workspace.
	#
	# There are two types of entries:
	#
	# ## REGULAR ENTRIES
	#
	# These entries expose an explicit list of files, they look like:
	#
	# name: (required)
	# Bazel filegroup name.
	# Type: string
	#
	# destinations: (required)
	# List of input files, relative to the top of the generated workspace.
	# Each one will appear in the `srcs` list of the corresponding
	# filegroup.
	#
	# sources: (required)
	# List of source files for the filegroup. Must have the same
	# size as the `destinations` list.
	# Type: list of paths relative to the root_build_dir
	#
	# gn_label:
	# GN label of target that defines this entry.
	# Type: GN label string
	#
	# They should generate Bazel targets that look like:
	#
	# filegroup(
	# name = "<name>",
	# srcs = [
	# <destination_1>,
	# <destination_2>,
	# ...
	# ],
	# )
	#
	# Where <destination_N> is the N-th entry in `destinations`, and will be
	# the path to a symlink (in the repository) to the corresponding
	# <sources_N> file.
	#
	# ## DIRECTORY ENTRIES
	#
	# These entries expose all files under a given output directory as
	# a single filegroup() using the glob() function. IMPORTANT: For
	# correctness, only use these when it is 100% sure that the content
	# of the source directory is re-created properly during incremental
	# builds. These look like:
	#
	# name: (required)
	# Bazel filegroup name.
	# Type: string
	#
	# source_dir: (required)
	# A source directory path, relative to the Ninja build output
	# directory, which will contain all input files for the Bazel
	# filegroup().
	#
	# dest_dir: (required)
	# A directory prefix for all input files, relative to the top of
	# the generated workspace. This will be a symlink to source_dir,
	# and the filegroup() will use a glob(["<dest_dir>/*"]) call to get all
	# files in it.
	#
	# gn_label: (optional)
	# GN label of target that defines this entry.
	# Type: GN label string
	#
	# They should generate Bazel targets that look like:
	#
	# filegroup(
	# name = "<name>",
	# srcs = glob(["<dest_dir>/**]),
	# )
	#
	# Where <dest_dir> is a repository symlink that points to source_dir.
	#
	generated_file(target_name) {
	forward_variables_from(invoker, [ "testonly" ])
	outputs = [ invoker.output ]
	data_keys = [ "bazel_inputs" ]
	walk_keys = [ "bazel_inputs_barrier" ]
	deps = invoker.inputs_deps
	output_conversion = "json"
	}
	}