build/toolchain/mac/BUILD.gn - gn - Git at Google

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.

 # TODO(brettw) Use "gcc_toolchain.gni" like the Linux toolchains. This requires
 # some enhancements since the commands on Mac are slightly different than on
 # Linux.

 import("../goma.gni")
 import("//build/config/clang/clang.gni")
 if (is_ios) {
   import("//build/config/ios/ios_sdk.gni")
 }
 import("//build/config/mac/mac_sdk.gni")
 import("//build/config/mac/symbols.gni")

 assert(host_os == "mac")

 import("//build/toolchain/cc_wrapper.gni")
 import("//build/toolchain/clang_static_analyzer.gni")
 import("//build/toolchain/goma.gni")
 import("//build/toolchain/toolchain.gni")
 import("//build/toolchain/concurrent_links.gni")

 declare_args() {
   # Reduce the number of tasks using the copy_bundle_data and compile_xcassets
   # tools as they can cause lots of I/O contention when invoking ninja with a
   # large number of parallel jobs (e.g. when using distributed build like goma).
   bundle_pool_depth = -1
 }

 if (current_toolchain == default_toolchain) {
   pool("bundle_pool") {
     if (bundle_pool_depth == -1) {
       depth = concurrent_links
     } else {
       depth = bundle_pool_depth
     }
   }
 }

 # When implementing tools using Python scripts, a TOOL_VERSION=N env
 # variable is placed in front of the command. The N should be incremented
 # whenever the script is changed, so that the build system rebuilds all
 # edges that utilize the script. Ideally this should be changed to use
 # proper input-dirty checking, but that could be expensive. Instead, use a
 # script to get the tool scripts' modification time to use as the version.
 # This won't cause a re-generation of GN files when the tool script changes
 # but it will cause edges to be marked as dirty if the ninja files are
 # regenerated. See https://crbug.com/619083 for details. A proper fix
 # would be to have inputs to tools (https://crbug.com/621119).
 tool_versions =
     exec_script("get_tool_mtime.py",
                 rebase_path([
                               "//build/toolchain/mac/compile_xcassets.py",
                               "//build/toolchain/mac/filter_libtool.py",
                               "//build/toolchain/mac/linker_driver.py",
                             ],
                             root_build_dir),
                 "trim scope")

 # Shared toolchain definition. Invocations should set current_os to set the
 # build args in this definition.
 template("mac_toolchain") {
   toolchain(target_name) {
     if (use_system_xcode) {
       env_wrapper = ""
     } else {
       env_wrapper = "export DEVELOPER_DIR=$hermetic_xcode_path; "
     }

     # When invoking this toolchain not as the default one, these args will be
     # passed to the build. They are ignored when this is the default toolchain.
     assert(defined(invoker.toolchain_args),
            "Toolchains must declare toolchain_args")
     toolchain_args = {
       # Populate toolchain args from the invoker.
       forward_variables_from(invoker.toolchain_args, "*")

       # The host toolchain value computed by the default toolchain's setup
       # needs to be passed through unchanged to all secondary toolchains to
       # ensure that it's always the same, regardless of the values that may be
       # set on those toolchains.
       host_toolchain = host_toolchain
     }

     # Supports building with the version of clang shipped with Xcode when
     # targeting iOS by not respecting clang_base_path.
     if (toolchain_args.current_os == "ios" && use_xcode_clang) {
       prefix = ""
     } else {
       prefix = rebase_path("$clang_base_path/bin/", root_build_dir)
     }

     _cc = "${prefix}clang"
     _cxx = "${prefix}clang++"

     # When the invoker has explicitly overridden use_goma or cc_wrapper in the
     # toolchain args, use those values, otherwise default to the global one.
     # This works because the only reasonable override that toolchains might
     # supply for these values are to force-disable them.
     if (defined(toolchain_args.use_goma)) {
       toolchain_uses_goma = toolchain_args.use_goma
     } else {
       toolchain_uses_goma = use_goma
     }
     if (defined(toolchain_args.cc_wrapper)) {
       toolchain_cc_wrapper = toolchain_args.cc_wrapper
     } else {
       toolchain_cc_wrapper = cc_wrapper
     }

     # Compute the compiler prefix.
     if (toolchain_uses_goma) {
       assert(toolchain_cc_wrapper == "",
              "Goma and cc_wrapper can't be used together.")
       compiler_prefix = "$goma_dir/gomacc "
     } else if (toolchain_cc_wrapper != "") {
       compiler_prefix = toolchain_cc_wrapper + " "
     } else {
       compiler_prefix = ""
     }

     cc = compiler_prefix + _cc
     cxx = compiler_prefix + _cxx
     ld = _cxx

     if (use_clang_static_analyzer) {
       analyzer_wrapper =
           rebase_path("//build/toolchain/clang_static_analyzer_wrapper.py",
                       root_build_dir) + "  --mode=clang"
       cc = analyzer_wrapper + " ${cc}"
       cxx = analyzer_wrapper + " ${cxx}"

       ld = cxx
     }

     linker_driver =
         "TOOL_VERSION=${tool_versions.linker_driver} " +
         rebase_path("//build/toolchain/mac/linker_driver.py", root_build_dir)

     # On iOS, the final applications are assembled using lipo (to support fat
     # builds). The correct flags are passed to the linker_driver.py script
     # directly during the lipo call.
     if (toolchain_args.current_os != "ios") {
       _enable_dsyms = enable_dsyms
       _save_unstripped_output = save_unstripped_output
     } else {
       _enable_dsyms = false
       _save_unstripped_output = false
     }

     # Make these apply to all tools below.
     lib_switch = "-l"
     lib_dir_switch = "-L"

     # Object files go in this directory. Use label_name instead of
     # target_output_name since labels will generally have no spaces and will be
     # unique in the directory.
     object_subdir = "{{target_out_dir}}/{{label_name}}"

     # If dSYMs are enabled, this flag will be added to the link tools.
     if (_enable_dsyms) {
       dsym_switch = " -Wcrl,dsym,{{root_out_dir}} "
       dsym_output_dir =
           "{{root_out_dir}}/{{target_output_name}}{{output_extension}}.dSYM"
       dsym_output = [
         "$dsym_output_dir/",
         "$dsym_output_dir/Contents/Info.plist",
         "$dsym_output_dir/Contents/Resources/DWARF/" +
             "{{target_output_name}}{{output_extension}}",
       ]
     } else {
       dsym_switch = ""
     }

     if (_save_unstripped_output) {
       _unstripped_output = "{{root_out_dir}}/{{target_output_name}}{{output_extension}}.unstripped"
     }

     tool("cc") {
       depfile = "{{output}}.d"
       precompiled_header_type = "gcc"
       command = "$env_wrapper $cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_c}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "CC {{output}}"
       outputs = [
         "$object_subdir/{{source_name_part}}.o",
       ]
     }

     tool("cxx") {
       depfile = "{{output}}.d"
       precompiled_header_type = "gcc"
       command = "$env_wrapper $cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "CXX {{output}}"
       outputs = [
         "$object_subdir/{{source_name_part}}.o",
       ]
     }

     tool("asm") {
       # For GCC we can just use the C compiler to compile assembly.
       depfile = "{{output}}.d"
       command = "$env_wrapper $cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{asmflags}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "ASM {{output}}"
       outputs = [
         "$object_subdir/{{source_name_part}}.o",
       ]
     }

     tool("objc") {
       depfile = "{{output}}.d"
       precompiled_header_type = "gcc"
       command = "$env_wrapper $cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_objc}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "OBJC {{output}}"
       outputs = [
         "$object_subdir/{{source_name_part}}.o",
       ]
     }

     tool("objcxx") {
       depfile = "{{output}}.d"
       precompiled_header_type = "gcc"
       command = "$env_wrapper $cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_objcc}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "OBJCXX {{output}}"
       outputs = [
         "$object_subdir/{{source_name_part}}.o",
       ]
     }

     tool("alink") {
       script =
           rebase_path("//build/toolchain/mac/filter_libtool.py", root_build_dir)

       # Note about -filelist: Apple's linker reads the file list file and
       # interprets each newline-separated chunk of text as a file name. It
       # doesn't do the things one would expect from the shell like unescaping
       # or handling quotes. In contrast, when Ninja finds a file name with
       # spaces, it single-quotes them in $inputs_newline as it would normally
       # do for command-line arguments. Thus any source names with spaces, or
       # label names with spaces (which GN bases the output paths on) will be
       # corrupted by this process. Don't use spaces for source files or labels.
       rspfile = "{{output}}.rsp"
       rspfile_content = "{{inputs_newline}}"
       command = "$env_wrapper rm -f {{output}} && TOOL_VERSION=${tool_versions.filter_libtool} python $script libtool -static {{arflags}} -o {{output}} -filelist $rspfile"
       description = "LIBTOOL-STATIC {{output}}"
       outputs = [
         "{{output_dir}}/{{target_output_name}}{{output_extension}}",
       ]
       default_output_dir = "{{target_out_dir}}"
       default_output_extension = ".a"
       output_prefix = "lib"
     }

     tool("solink") {
       dylib = "{{output_dir}}/{{target_output_name}}{{output_extension}}"  # eg "./libfoo.dylib"
       rspfile = dylib + ".rsp"
       pool = "//build/toolchain:link_pool($default_toolchain)"

       # These variables are not built into GN but are helpers that implement
       # (1) linking to produce a .dylib, (2) extracting the symbols from that
       # file to a temporary file, (3) if the temporary file has differences from
       # the existing .TOC file, overwrite it, otherwise, don't change it.
       #
       # As a special case, if the library reexports symbols from other dynamic
       # libraries, we always update the .TOC and skip the temporary file and
       # diffing steps, since that library always needs to be re-linked.
       tocname = dylib + ".TOC"
       temporary_tocname = dylib + ".tmp"

       does_reexport_command = "[ ! -e \"$dylib\" -o ! -e \"$tocname\" ] || otool -l \"$dylib\" | grep -q LC_REEXPORT_DYLIB"

       link_command = "$linker_driver $ld -shared "
       if (is_component_build) {
         link_command += " -Wl,-install_name,@rpath/\"{{target_output_name}}{{output_extension}}\" "
       }
       link_command += dsym_switch
       link_command += "{{ldflags}} -o \"$dylib\" -Wl,-filelist,\"$rspfile\" {{libs}} {{solibs}}"

       replace_command = "if ! cmp -s \"$temporary_tocname\" \"$tocname\"; then mv \"$temporary_tocname\" \"$tocname\""
       extract_toc_command = "{ otool -l \"$dylib\" | grep LC_ID_DYLIB -A 5; nm -gP \"$dylib\" | cut -f1-2 -d' ' | grep -v U\$\$; true; }"

       command = "$env_wrapper if $does_reexport_command ; then $link_command && $extract_toc_command > \"$tocname\"; else $link_command && $extract_toc_command > \"$temporary_tocname\" && $replace_command ; fi; fi"

       rspfile_content = "{{inputs_newline}}"

       description = "SOLINK {{output}}"

       # Use this for {{output_extension}} expansions unless a target manually
       # overrides it (in which case {{output_extension}} will be what the target
       # specifies).
       default_output_dir = "{{root_out_dir}}"
       default_output_extension = ".dylib"

       output_prefix = "lib"

       # Since the above commands only updates the .TOC file when it changes, ask
       # Ninja to check if the timestamp actually changed to know if downstream
       # dependencies should be recompiled.
       restat = true

       # Tell GN about the output files. It will link to the dylib but use the
       # tocname for dependency management.
       outputs = [
         dylib,
         tocname,
       ]
       link_output = dylib
       depend_output = tocname

       if (_enable_dsyms) {
         outputs += dsym_output
       }
       if (_save_unstripped_output) {
         outputs += [ _unstripped_output ]
       }
     }

     tool("solink_module") {
       sofile = "{{output_dir}}/{{target_output_name}}{{output_extension}}"  # eg "./libfoo.so"
       rspfile = sofile + ".rsp"
       pool = "//build/toolchain:link_pool($default_toolchain)"

       link_command = "$env_wrapper $linker_driver $ld -bundle {{ldflags}} -o \"$sofile\" -Wl,-filelist,\"$rspfile\""
       if (is_component_build) {
         link_command += " -Wl,-install_name,@rpath/{{target_output_name}}{{output_extension}}"
       }
       link_command += dsym_switch
       link_command += " {{solibs}} {{libs}}"
       command = link_command

       rspfile_content = "{{inputs_newline}}"

       description = "SOLINK_MODULE {{output}}"

       # Use this for {{output_extension}} expansions unless a target manually
       # overrides it (in which case {{output_extension}} will be what the target
       # specifies).
       default_output_dir = "{{root_out_dir}}"
       default_output_extension = ".so"

       outputs = [
         sofile,
       ]

       if (_enable_dsyms) {
         outputs += dsym_output
       }
       if (_save_unstripped_output) {
         outputs += [ _unstripped_output ]
       }
     }

     tool("link") {
       outfile = "{{output_dir}}/{{target_output_name}}{{output_extension}}"
       rspfile = "$outfile.rsp"
       pool = "//build/toolchain:link_pool($default_toolchain)"

       # Note about -filelist: Apple's linker reads the file list file and
       # interprets each newline-separated chunk of text as a file name. It
       # doesn't do the things one would expect from the shell like unescaping
       # or handling quotes. In contrast, when Ninja finds a file name with
       # spaces, it single-quotes them in $inputs_newline as it would normally
       # do for command-line arguments. Thus any source names with spaces, or
       # label names with spaces (which GN bases the output paths on) will be
       # corrupted by this process. Don't use spaces for source files or labels.
       command = "$env_wrapper $linker_driver $ld $dsym_switch {{ldflags}} -o \"$outfile\" -Wl,-filelist,\"$rspfile\" {{solibs}} {{libs}}"
       description = "LINK $outfile"
       rspfile_content = "{{inputs_newline}}"
       outputs = [
         outfile,
       ]

       if (_enable_dsyms) {
         outputs += dsym_output
       }
       if (_save_unstripped_output) {
         outputs += [ _unstripped_output ]
       }

       default_output_dir = "{{root_out_dir}}"
     }

     # These two are really entirely generic, but have to be repeated in
     # each toolchain because GN doesn't allow a template to be used here.
     # See //build/toolchain/toolchain.gni for details.
     tool("stamp") {
       command = stamp_command
       description = stamp_description
     }
     tool("copy") {
       command = copy_command
       description = copy_description
     }

     tool("copy_bundle_data") {
       # copy_command use hardlink if possible but this does not work with
       # directories. If source is a directory, instead use "pax" to create
       # the same tree structure using hardlinks to individual files (this
       # preserve symbolic links too) as recommended in the replies to the
       # question at http://serverfault.com/q/209888/43689 ("cp -al" isn't
       # available on macOS).
       #
       # According to the man page for pax, the commands to use to clone
       # olddir to newdir using pax are the following:
       #
       #   $ mkdir newdir
       #   $ cd olddir
       #   $ pax -rwl . ../newdir
       #
       # The _copydir command does exactly that but use an absolute path
       # constructed using shell variable $OLDPWD (automatically set when
       # cd is used) as computing the relative path is a bit complex and
       # using pwd would requires a sub-shell to be created.
       _copydir = "mkdir -p {{output}} && cd {{source}} && " +
                  "pax -rwl . \"\$OLDPWD\"/{{output}}"
       command = "rm -rf {{output}} && if [[ -d {{source}} ]]; then " +
                 _copydir + "; else " + copy_command + "; fi"

       description = "COPY_BUNDLE_DATA {{source}} {{output}}"
       pool = ":bundle_pool($default_toolchain)"
     }
     tool("compile_xcassets") {
       _tool = rebase_path("//build/toolchain/mac/compile_xcassets.py",
                           root_build_dir)
       if (is_ios) {
         _sdk_name = ios_sdk_name
         _min_deployment_target = ios_deployment_target
         _compress_pngs = ""
       } else {
         _sdk_name = mac_sdk_name
         _min_deployment_target = mac_deployment_target
         _compress_pngs = " -c "
       }
       command =
           "$env_wrapper rm -f \"{{output}}\" && " +
           "TOOL_VERSION=${tool_versions.compile_xcassets} " +
           "python $_tool$_compress_pngs -p \"$_sdk_name\" " +
           "-t \"$_min_deployment_target\" -T \"{{bundle_product_type}}\" " +
           "-P \"{{bundle_partial_info_plist}}\" -o {{output}} {{inputs}}"

       description = "COMPILE_XCASSETS {{output}}"
       pool = ":bundle_pool($default_toolchain)"
     }

     tool("action") {
       pool = "//build/toolchain:action_pool($default_toolchain)"
     }
   }
 }

 mac_toolchain("clang_arm") {
   toolchain_args = {
     current_cpu = "arm"
     current_os = "mac"
   }
 }

 mac_toolchain("clang_x64") {
   toolchain_args = {
     current_cpu = "x64"
     current_os = "mac"

     if (target_os == "ios") {
       # TODO(crbug.com/753445): the use_sanitizer_coverage arg is currently
       # not supported by the Chromium mac_clang_x64 toolchain on iOS
       # distribution.
       use_sanitizer_coverage = false
     }
   }
 }

 mac_toolchain("clang_x86") {
   toolchain_args = {
     current_cpu = "x86"
     current_os = "mac"
   }
 }

 mac_toolchain("clang_x86_v8_arm") {
   toolchain_args = {
     current_cpu = "x86"
     v8_current_cpu = "arm"
     current_os = "mac"
   }
 }

 mac_toolchain("clang_x86_v8_mipsel") {
   toolchain_args = {
     current_cpu = "x86"
     v8_current_cpu = "mipsel"
     current_os = "mac"
   }
 }

 mac_toolchain("clang_x64_v8_arm64") {
   toolchain_args = {
     current_cpu = "x64"
     v8_current_cpu = "arm64"
     current_os = "mac"
   }
 }

 mac_toolchain("clang_x64_v8_mips64el") {
   toolchain_args = {
     current_cpu = "x64"
     v8_current_cpu = "mips64el"
     current_os = "mac"
   }
 }

 if (is_ios) {
   mac_toolchain("ios_clang_arm") {
     toolchain_args = {
       current_cpu = "arm"
       current_os = "ios"
     }
   }

   mac_toolchain("ios_clang_arm64") {
     toolchain_args = {
       current_cpu = "arm64"
       current_os = "ios"
     }
   }

   mac_toolchain("ios_clang_x86") {
     toolchain_args = {
       current_cpu = "x86"
       current_os = "ios"
     }
   }

   mac_toolchain("ios_clang_x64") {
     toolchain_args = {
       current_cpu = "x64"
       current_os = "ios"
     }
   }
 }
	# Copyright (c) 2013 The Chromium Authors. All rights reserved.
	# Use of this source code is governed by a BSD-style license that can be
	# found in the LICENSE file.

	# TODO(brettw) Use "gcc_toolchain.gni" like the Linux toolchains. This requires
	# some enhancements since the commands on Mac are slightly different than on
	# Linux.

	import("../goma.gni")
	import("//build/config/clang/clang.gni")
	if (is_ios) {
	import("//build/config/ios/ios_sdk.gni")
	}
	import("//build/config/mac/mac_sdk.gni")
	import("//build/config/mac/symbols.gni")

	assert(host_os == "mac")

	import("//build/toolchain/cc_wrapper.gni")
	import("//build/toolchain/clang_static_analyzer.gni")
	import("//build/toolchain/goma.gni")
	import("//build/toolchain/toolchain.gni")
	import("//build/toolchain/concurrent_links.gni")

	declare_args() {
	# Reduce the number of tasks using the copy_bundle_data and compile_xcassets
	# tools as they can cause lots of I/O contention when invoking ninja with a
	# large number of parallel jobs (e.g. when using distributed build like goma).
	bundle_pool_depth = -1
	}

	if (current_toolchain == default_toolchain) {
	pool("bundle_pool") {
	if (bundle_pool_depth == -1) {
	depth = concurrent_links
	} else {
	depth = bundle_pool_depth
	}
	}
	}

	# When implementing tools using Python scripts, a TOOL_VERSION=N env
	# variable is placed in front of the command. The N should be incremented
	# whenever the script is changed, so that the build system rebuilds all
	# edges that utilize the script. Ideally this should be changed to use
	# proper input-dirty checking, but that could be expensive. Instead, use a
	# script to get the tool scripts' modification time to use as the version.
	# This won't cause a re-generation of GN files when the tool script changes
	# but it will cause edges to be marked as dirty if the ninja files are
	# regenerated. See https://crbug.com/619083 for details. A proper fix
	# would be to have inputs to tools (https://crbug.com/621119).
	tool_versions =
	exec_script("get_tool_mtime.py",
	rebase_path([
	"//build/toolchain/mac/compile_xcassets.py",
	"//build/toolchain/mac/filter_libtool.py",
	"//build/toolchain/mac/linker_driver.py",
	],
	root_build_dir),
	"trim scope")

	# Shared toolchain definition. Invocations should set current_os to set the
	# build args in this definition.
	template("mac_toolchain") {
	toolchain(target_name) {
	if (use_system_xcode) {
	env_wrapper = ""
	} else {
	env_wrapper = "export DEVELOPER_DIR=$hermetic_xcode_path; "
	}

	# When invoking this toolchain not as the default one, these args will be
	# passed to the build. They are ignored when this is the default toolchain.
	assert(defined(invoker.toolchain_args),
	"Toolchains must declare toolchain_args")
	toolchain_args = {
	# Populate toolchain args from the invoker.
	forward_variables_from(invoker.toolchain_args, "*")

	# The host toolchain value computed by the default toolchain's setup
	# needs to be passed through unchanged to all secondary toolchains to
	# ensure that it's always the same, regardless of the values that may be
	# set on those toolchains.
	host_toolchain = host_toolchain
	}

	# Supports building with the version of clang shipped with Xcode when
	# targeting iOS by not respecting clang_base_path.
	if (toolchain_args.current_os == "ios" && use_xcode_clang) {
	prefix = ""
	} else {
	prefix = rebase_path("$clang_base_path/bin/", root_build_dir)
	}

	_cc = "${prefix}clang"
	_cxx = "${prefix}clang++"

	# When the invoker has explicitly overridden use_goma or cc_wrapper in the
	# toolchain args, use those values, otherwise default to the global one.
	# This works because the only reasonable override that toolchains might
	# supply for these values are to force-disable them.
	if (defined(toolchain_args.use_goma)) {
	toolchain_uses_goma = toolchain_args.use_goma
	} else {
	toolchain_uses_goma = use_goma
	}
	if (defined(toolchain_args.cc_wrapper)) {
	toolchain_cc_wrapper = toolchain_args.cc_wrapper
	} else {
	toolchain_cc_wrapper = cc_wrapper
	}

	# Compute the compiler prefix.
	if (toolchain_uses_goma) {
	assert(toolchain_cc_wrapper == "",
	"Goma and cc_wrapper can't be used together.")
	compiler_prefix = "$goma_dir/gomacc "
	} else if (toolchain_cc_wrapper != "") {
	compiler_prefix = toolchain_cc_wrapper + " "
	} else {
	compiler_prefix = ""
	}

	cc = compiler_prefix + _cc
	cxx = compiler_prefix + _cxx
	ld = _cxx

	if (use_clang_static_analyzer) {
	analyzer_wrapper =
	rebase_path("//build/toolchain/clang_static_analyzer_wrapper.py",
	root_build_dir) + " --mode=clang"
	cc = analyzer_wrapper + " ${cc}"
	cxx = analyzer_wrapper + " ${cxx}"

	ld = cxx
	}

	linker_driver =
	"TOOL_VERSION=${tool_versions.linker_driver} " +
	rebase_path("//build/toolchain/mac/linker_driver.py", root_build_dir)

	# On iOS, the final applications are assembled using lipo (to support fat
	# builds). The correct flags are passed to the linker_driver.py script
	# directly during the lipo call.
	if (toolchain_args.current_os != "ios") {
	_enable_dsyms = enable_dsyms
	_save_unstripped_output = save_unstripped_output
	} else {
	_enable_dsyms = false
	_save_unstripped_output = false
	}

	# Make these apply to all tools below.
	lib_switch = "-l"
	lib_dir_switch = "-L"

	# Object files go in this directory. Use label_name instead of
	# target_output_name since labels will generally have no spaces and will be
	# unique in the directory.
	object_subdir = "{{target_out_dir}}/{{label_name}}"

	# If dSYMs are enabled, this flag will be added to the link tools.
	if (_enable_dsyms) {
	dsym_switch = " -Wcrl,dsym,{{root_out_dir}} "
	dsym_output_dir =
	"{{root_out_dir}}/{{target_output_name}}{{output_extension}}.dSYM"
	dsym_output = [
	"$dsym_output_dir/",
	"$dsym_output_dir/Contents/Info.plist",
	"$dsym_output_dir/Contents/Resources/DWARF/" +
	"{{target_output_name}}{{output_extension}}",
	]
	} else {
	dsym_switch = ""
	}

	if (_save_unstripped_output) {
	_unstripped_output = "{{root_out_dir}}/{{target_output_name}}{{output_extension}}.unstripped"
	}

	tool("cc") {
	depfile = "{{output}}.d"
	precompiled_header_type = "gcc"
	command = "$env_wrapper $cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_c}} -c {{source}} -o {{output}}"
	depsformat = "gcc"
	description = "CC {{output}}"
	outputs = [
	"$object_subdir/{{source_name_part}}.o",
	]
	}

	tool("cxx") {
	depfile = "{{output}}.d"
	precompiled_header_type = "gcc"
	command = "$env_wrapper $cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}} -c {{source}} -o {{output}}"
	depsformat = "gcc"
	description = "CXX {{output}}"
	outputs = [
	"$object_subdir/{{source_name_part}}.o",
	]
	}

	tool("asm") {
	# For GCC we can just use the C compiler to compile assembly.
	depfile = "{{output}}.d"
	command = "$env_wrapper $cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{asmflags}} -c {{source}} -o {{output}}"
	depsformat = "gcc"
	description = "ASM {{output}}"
	outputs = [
	"$object_subdir/{{source_name_part}}.o",
	]
	}

	tool("objc") {
	depfile = "{{output}}.d"
	precompiled_header_type = "gcc"
	command = "$env_wrapper $cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_objc}} -c {{source}} -o {{output}}"
	depsformat = "gcc"
	description = "OBJC {{output}}"
	outputs = [
	"$object_subdir/{{source_name_part}}.o",
	]
	}

	tool("objcxx") {
	depfile = "{{output}}.d"
	precompiled_header_type = "gcc"
	command = "$env_wrapper $cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_objcc}} -c {{source}} -o {{output}}"
	depsformat = "gcc"
	description = "OBJCXX {{output}}"
	outputs = [
	"$object_subdir/{{source_name_part}}.o",
	]
	}

	tool("alink") {
	script =
	rebase_path("//build/toolchain/mac/filter_libtool.py", root_build_dir)

	# Note about -filelist: Apple's linker reads the file list file and
	# interprets each newline-separated chunk of text as a file name. It
	# doesn't do the things one would expect from the shell like unescaping
	# or handling quotes. In contrast, when Ninja finds a file name with
	# spaces, it single-quotes them in $inputs_newline as it would normally
	# do for command-line arguments. Thus any source names with spaces, or
	# label names with spaces (which GN bases the output paths on) will be
	# corrupted by this process. Don't use spaces for source files or labels.
	rspfile = "{{output}}.rsp"
	rspfile_content = "{{inputs_newline}}"
	command = "$env_wrapper rm -f {{output}} && TOOL_VERSION=${tool_versions.filter_libtool} python $script libtool -static {{arflags}} -o {{output}} -filelist $rspfile"
	description = "LIBTOOL-STATIC {{output}}"
	outputs = [
	"{{output_dir}}/{{target_output_name}}{{output_extension}}",
	]
	default_output_dir = "{{target_out_dir}}"
	default_output_extension = ".a"
	output_prefix = "lib"
	}

	tool("solink") {
	dylib = "{{output_dir}}/{{target_output_name}}{{output_extension}}" # eg "./libfoo.dylib"
	rspfile = dylib + ".rsp"
	pool = "//build/toolchain:link_pool($default_toolchain)"

	# These variables are not built into GN but are helpers that implement
	# (1) linking to produce a .dylib, (2) extracting the symbols from that
	# file to a temporary file, (3) if the temporary file has differences from
	# the existing .TOC file, overwrite it, otherwise, don't change it.
	#
	# As a special case, if the library reexports symbols from other dynamic
	# libraries, we always update the .TOC and skip the temporary file and
	# diffing steps, since that library always needs to be re-linked.
	tocname = dylib + ".TOC"
	temporary_tocname = dylib + ".tmp"

	does_reexport_command = "[ ! -e \"$dylib\" -o ! -e \"$tocname\" ] \|\| otool -l \"$dylib\" \| grep -q LC_REEXPORT_DYLIB"

	link_command = "$linker_driver $ld -shared "
	if (is_component_build) {
	link_command += " -Wl,-install_name,@rpath/\"{{target_output_name}}{{output_extension}}\" "
	}
	link_command += dsym_switch
	link_command += "{{ldflags}} -o \"$dylib\" -Wl,-filelist,\"$rspfile\" {{libs}} {{solibs}}"

	replace_command = "if ! cmp -s \"$temporary_tocname\" \"$tocname\"; then mv \"$temporary_tocname\" \"$tocname\""
	extract_toc_command = "{ otool -l \"$dylib\" \| grep LC_ID_DYLIB -A 5; nm -gP \"$dylib\" \| cut -f1-2 -d' ' \| grep -v U\$\$; true; }"

	command = "$env_wrapper if $does_reexport_command ; then $link_command && $extract_toc_command > \"$tocname\"; else $link_command && $extract_toc_command > \"$temporary_tocname\" && $replace_command ; fi; fi"

	rspfile_content = "{{inputs_newline}}"

	description = "SOLINK {{output}}"

	# Use this for {{output_extension}} expansions unless a target manually
	# overrides it (in which case {{output_extension}} will be what the target
	# specifies).
	default_output_dir = "{{root_out_dir}}"
	default_output_extension = ".dylib"

	output_prefix = "lib"

	# Since the above commands only updates the .TOC file when it changes, ask
	# Ninja to check if the timestamp actually changed to know if downstream
	# dependencies should be recompiled.
	restat = true

	# Tell GN about the output files. It will link to the dylib but use the
	# tocname for dependency management.
	outputs = [
	dylib,
	tocname,
	]
	link_output = dylib
	depend_output = tocname

	if (_enable_dsyms) {
	outputs += dsym_output
	}
	if (_save_unstripped_output) {
	outputs += [ _unstripped_output ]
	}
	}

	tool("solink_module") {
	sofile = "{{output_dir}}/{{target_output_name}}{{output_extension}}" # eg "./libfoo.so"
	rspfile = sofile + ".rsp"
	pool = "//build/toolchain:link_pool($default_toolchain)"

	link_command = "$env_wrapper $linker_driver $ld -bundle {{ldflags}} -o \"$sofile\" -Wl,-filelist,\"$rspfile\""
	if (is_component_build) {
	link_command += " -Wl,-install_name,@rpath/{{target_output_name}}{{output_extension}}"
	}
	link_command += dsym_switch
	link_command += " {{solibs}} {{libs}}"
	command = link_command

	rspfile_content = "{{inputs_newline}}"

	description = "SOLINK_MODULE {{output}}"

	# Use this for {{output_extension}} expansions unless a target manually
	# overrides it (in which case {{output_extension}} will be what the target
	# specifies).
	default_output_dir = "{{root_out_dir}}"
	default_output_extension = ".so"

	outputs = [
	sofile,
	]

	if (_enable_dsyms) {
	outputs += dsym_output
	}
	if (_save_unstripped_output) {
	outputs += [ _unstripped_output ]
	}
	}

	tool("link") {
	outfile = "{{output_dir}}/{{target_output_name}}{{output_extension}}"
	rspfile = "$outfile.rsp"
	pool = "//build/toolchain:link_pool($default_toolchain)"

	# Note about -filelist: Apple's linker reads the file list file and
	# interprets each newline-separated chunk of text as a file name. It
	# doesn't do the things one would expect from the shell like unescaping
	# or handling quotes. In contrast, when Ninja finds a file name with
	# spaces, it single-quotes them in $inputs_newline as it would normally
	# do for command-line arguments. Thus any source names with spaces, or
	# label names with spaces (which GN bases the output paths on) will be
	# corrupted by this process. Don't use spaces for source files or labels.
	command = "$env_wrapper $linker_driver $ld $dsym_switch {{ldflags}} -o \"$outfile\" -Wl,-filelist,\"$rspfile\" {{solibs}} {{libs}}"
	description = "LINK $outfile"
	rspfile_content = "{{inputs_newline}}"
	outputs = [
	outfile,
	]

	if (_enable_dsyms) {
	outputs += dsym_output
	}
	if (_save_unstripped_output) {
	outputs += [ _unstripped_output ]
	}

	default_output_dir = "{{root_out_dir}}"
	}

	# These two are really entirely generic, but have to be repeated in
	# each toolchain because GN doesn't allow a template to be used here.
	# See //build/toolchain/toolchain.gni for details.
	tool("stamp") {
	command = stamp_command
	description = stamp_description
	}
	tool("copy") {
	command = copy_command
	description = copy_description
	}

	tool("copy_bundle_data") {
	# copy_command use hardlink if possible but this does not work with
	# directories. If source is a directory, instead use "pax" to create
	# the same tree structure using hardlinks to individual files (this
	# preserve symbolic links too) as recommended in the replies to the
	# question at http://serverfault.com/q/209888/43689 ("cp -al" isn't
	# available on macOS).
	#
	# According to the man page for pax, the commands to use to clone
	# olddir to newdir using pax are the following:
	#
	# $ mkdir newdir
	# $ cd olddir
	# $ pax -rwl . ../newdir
	#
	# The _copydir command does exactly that but use an absolute path
	# constructed using shell variable $OLDPWD (automatically set when
	# cd is used) as computing the relative path is a bit complex and
	# using pwd would requires a sub-shell to be created.
	_copydir = "mkdir -p {{output}} && cd {{source}} && " +
	"pax -rwl . \"\$OLDPWD\"/{{output}}"
	command = "rm -rf {{output}} && if [[ -d {{source}} ]]; then " +
	_copydir + "; else " + copy_command + "; fi"

	description = "COPY_BUNDLE_DATA {{source}} {{output}}"
	pool = ":bundle_pool($default_toolchain)"
	}
	tool("compile_xcassets") {
	_tool = rebase_path("//build/toolchain/mac/compile_xcassets.py",
	root_build_dir)
	if (is_ios) {
	_sdk_name = ios_sdk_name
	_min_deployment_target = ios_deployment_target
	_compress_pngs = ""
	} else {
	_sdk_name = mac_sdk_name
	_min_deployment_target = mac_deployment_target
	_compress_pngs = " -c "
	}
	command =
	"$env_wrapper rm -f \"{{output}}\" && " +
	"TOOL_VERSION=${tool_versions.compile_xcassets} " +
	"python $_tool$_compress_pngs -p \"$_sdk_name\" " +
	"-t \"$_min_deployment_target\" -T \"{{bundle_product_type}}\" " +
	"-P \"{{bundle_partial_info_plist}}\" -o {{output}} {{inputs}}"

	description = "COMPILE_XCASSETS {{output}}"
	pool = ":bundle_pool($default_toolchain)"
	}

	tool("action") {
	pool = "//build/toolchain:action_pool($default_toolchain)"
	}
	}
	}

	mac_toolchain("clang_arm") {
	toolchain_args = {
	current_cpu = "arm"
	current_os = "mac"
	}
	}

	mac_toolchain("clang_x64") {
	toolchain_args = {
	current_cpu = "x64"
	current_os = "mac"

	if (target_os == "ios") {
	# TODO(crbug.com/753445): the use_sanitizer_coverage arg is currently
	# not supported by the Chromium mac_clang_x64 toolchain on iOS
	# distribution.
	use_sanitizer_coverage = false
	}
	}
	}

	mac_toolchain("clang_x86") {
	toolchain_args = {
	current_cpu = "x86"
	current_os = "mac"
	}
	}

	mac_toolchain("clang_x86_v8_arm") {
	toolchain_args = {
	current_cpu = "x86"
	v8_current_cpu = "arm"
	current_os = "mac"
	}
	}

	mac_toolchain("clang_x86_v8_mipsel") {
	toolchain_args = {
	current_cpu = "x86"
	v8_current_cpu = "mipsel"
	current_os = "mac"
	}
	}

	mac_toolchain("clang_x64_v8_arm64") {
	toolchain_args = {
	current_cpu = "x64"
	v8_current_cpu = "arm64"
	current_os = "mac"
	}
	}

	mac_toolchain("clang_x64_v8_mips64el") {
	toolchain_args = {
	current_cpu = "x64"
	v8_current_cpu = "mips64el"
	current_os = "mac"
	}
	}

	if (is_ios) {
	mac_toolchain("ios_clang_arm") {
	toolchain_args = {
	current_cpu = "arm"
	current_os = "ios"
	}
	}

	mac_toolchain("ios_clang_arm64") {
	toolchain_args = {
	current_cpu = "arm64"
	current_os = "ios"
	}
	}

	mac_toolchain("ios_clang_x86") {
	toolchain_args = {
	current_cpu = "x86"
	current_os = "ios"
	}
	}

	mac_toolchain("ios_clang_x64") {
	toolchain_args = {
	current_cpu = "x64"
	current_os = "ios"
	}
	}
	}