tools/build_rules/go/def.bzl - bazel - Git at Google

 # Copyright 2014 The Bazel Authors. 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.

 """These are bare-bones Go rules.

 In order of priority:

 - No support for build tags

 - BUILD file must be written by hand.

 - No C++ interop (SWIG, cgo).

 - No test sharding or test XML.

 """

 _DEFAULT_LIB = "go_default_library"

 _VENDOR_PREFIX = "/vendor/"

 go_filetype = FileType([".go"])

 ################

 # In Go, imports are always fully qualified with a URL,
 # eg. github.com/user/project. Hence, a label //foo:bar from within a
 # Bazel workspace must be referred to as
 # "github.com/user/project/foo/bar". To make this work, each rule must
 # know the repository's URL. This is achieved, by having all go rules
 # depend on a globally unique target that has a "go_prefix" transitive
 # info provider.

 def _go_prefix_impl(ctx):
   """go_prefix_impl provides the go prefix to use as a transitive info provider."""
   return struct(go_prefix = ctx.attr.prefix)

 def _go_prefix(ctx):
   """slash terminated go-prefix"""
   prefix = ctx.attr.go_prefix.go_prefix
   if prefix != "" and not prefix.endswith("/"):
     prefix = prefix + "/"
   return prefix

 _go_prefix_rule = rule(
     _go_prefix_impl,
     attrs = {
         "prefix": attr.string(mandatory = True),
     },
 )

 def go_prefix(prefix):
   """go_prefix sets the Go import name to be used for this workspace."""
   _go_prefix_rule(name = "go_prefix",
     prefix = prefix,
     visibility = ["//visibility:public" ]
   )

 ################

 # TODO(bazel-team): it would be nice if Bazel had this built-in.
 def symlink_tree_commands(dest_dir, artifact_dict):
   """Symlink_tree_commands returns a list of commands to create the
   dest_dir, and populate it according to the given dict.

   Args:
     dest_dir: The destination directory, a string.
     artifact_dict: The mapping of exec-path => path in the dest_dir.

   Returns:
     A list of commands that will setup the symlink tree.
   """
   cmds = [
     "rm -rf " + dest_dir,
     "mkdir -p " + dest_dir,
   ]

   for old_path, new_path in artifact_dict.items():
     new_dir = new_path[:new_path.rfind('/')]
     up = (new_dir.count('/') + 1 +
           dest_dir.count('/') + 1)
     cmds += [
       "mkdir -p %s/%s" % (dest_dir, new_dir),
       "ln -s %s%s %s/%s" % ('../' * up, old_path, dest_dir, new_path),
     ]
   return cmds

 def go_environment_vars(ctx):
   """Return a map of environment variables for use with actions, based on
   the arguments. Uses the ctx.fragments.cpp.cpu attribute, if present,
   and picks a default of target_os="linux" and target_arch="amd64"
   otherwise.

   Args:
     The skylark Context.

   Returns:
     A dict of environment variables for running Go tool commands that build for
     the target OS and architecture.
   """
   bazel_to_go_toolchain = {"k8": {"GOOS": "linux",
                                   "GOARCH": "amd64"},
                            "piii": {"GOOS": "linux",
                                     "GOARCH": "386"},
                            "darwin": {"GOOS": "darwin",
                                       "GOARCH": "amd64"},
                            "freebsd": {"GOOS": "freebsd",
                                        "GOARCH": "amd64"},
                            "armeabi-v7a": {"GOOS": "linux",
                                            "GOARCH": "arm"},
                            "arm": {"GOOS": "linux",
                                    "GOARCH": "arm"}}
   return bazel_to_go_toolchain.get(ctx.fragments.cpp.cpu,
                                    {"GOOS": "linux",
                                     "GOARCH": "amd64"})

 def emit_go_compile_action(ctx, sources, deps, out_lib):
   """Construct the command line for compiling Go code.
   Constructs a symlink tree to accomodate for workspace name.

   Args:
     ctx: The skylark Context.
     sources: an iterable of source code artifacts (or CTs? or labels?)
     deps: an iterable of dependencies. Each dependency d should have an
       artifact in d.go_library_object representing an imported library.
     out_lib: the artifact (configured target?) that should be produced
   """
   config_strip = len(ctx.configuration.bin_dir.path) + 1

   out_dir = out_lib.path + ".dir"
   out_depth = out_dir.count('/') + 1
   tree_layout = {}
   inputs = []
   prefix = _go_prefix(ctx)
   import_map = {}
   for d in deps:
     library_artifact_path = d.go_library_object.path[config_strip:]
     tree_layout[d.go_library_object.path] = prefix + library_artifact_path
     inputs += [d.go_library_object]

     source_import = prefix + d.label.package + "/" + d.label.name
     actual_import = prefix + d.label.package + "/" + d.label.name
     if d.label.name == _DEFAULT_LIB:
       source_import = prefix + d.label.package

     if source_import.rfind(_VENDOR_PREFIX) != -1:
       source_import = source_import[len(_VENDOR_PREFIX) + source_import.rfind(_VENDOR_PREFIX):]

     if source_import != actual_import:
       if source_import in import_map:
         fail("duplicate import %s: adding %s and have %s"
              % (source_import, actual_import, import_map[source_import]))
       import_map[source_import] = actual_import

   inputs += list(sources)
   for s in sources:
     tree_layout[s.path] = prefix + s.path

   cmds = symlink_tree_commands(out_dir, tree_layout)
   args = [
       "cd ", out_dir, "&&",
       ('../' * out_depth) + ctx.file.go_tool.path,
       "tool", "compile",
       "-o", ('../' * out_depth) + out_lib.path, "-pack",

       # Import path.
       "-I", "."] + [
         "-importmap=%s=%s" % (k,v) for k, v in import_map.items()
       ]

   # Set -p to the import path of the library, ie.
   # (ctx.label.package + "/" ctx.label.name) for now.
   cmds += [ "export GOROOT=$(pwd)/" + ctx.file.go_tool.dirname + "/..",
     ' '.join(args + cmd_helper.template(sources, prefix + "%{path}"))]

   ctx.action(
       inputs = inputs + ctx.files.toolchain,
       outputs = [out_lib],
       mnemonic = "GoCompile",
       command =  " && ".join(cmds),
       env = go_environment_vars(ctx))

 def go_library_impl(ctx):
   """Implements the go_library() rule."""

   sources = set(ctx.files.srcs)
   deps = ctx.attr.deps
   if ctx.attr.library:
     sources += ctx.attr.library.go_sources
     deps += ctx.attr.library.direct_deps

   if not sources:
     fail("may not be empty", "srcs")

   out_lib = ctx.outputs.lib
   emit_go_compile_action(ctx, set(sources), deps, out_lib)

   transitive_libs = set([out_lib])
   for dep in ctx.attr.deps:
      transitive_libs += dep.transitive_go_library_object

   runfiles = ctx.runfiles(collect_data = True)
   return struct(
     label = ctx.label,
     files = set([out_lib]),
     direct_deps = deps,
     runfiles = runfiles,
     go_sources = sources,
     go_library_object = out_lib,
     transitive_go_library_object = transitive_libs)

 def emit_go_link_action(ctx, transitive_libs, lib, executable):
   """Sets up a symlink tree to libraries to link together."""
   out_dir = executable.path + ".dir"
   out_depth = out_dir.count('/') + 1
   tree_layout = {}

   config_strip = len(ctx.configuration.bin_dir.path) + 1
   prefix = _go_prefix(ctx)

   for l in transitive_libs:
     library_artifact_path = l.path[config_strip:]
     tree_layout[l.path] = prefix + library_artifact_path

   tree_layout[lib.path] = prefix + lib.path[config_strip:]
   tree_layout[executable.path] = prefix + executable.path[config_strip:]

   cmds = symlink_tree_commands(out_dir, tree_layout)
   cmds += [
     "export GOROOT=$(pwd)/" + ctx.file.go_tool.dirname + "/..",
     "cd " + out_dir,
     ' '.join([
       ('../' * out_depth) + ctx.file.go_tool.path,
       "tool", "link", "-L", ".",
       "-o", prefix + executable.path[config_strip:],
       prefix + lib.path[config_strip:]])]

   ctx.action(
       inputs = list(transitive_libs) + [lib] + ctx.files.toolchain,
       outputs = [executable],
       command = ' && '.join(cmds),
       mnemonic = "GoLink",
       env = go_environment_vars(ctx))

 def go_binary_impl(ctx):
   """go_binary_impl emits actions for compiling and linking a go executable."""
   lib_result = go_library_impl(ctx)
   executable = ctx.outputs.executable
   lib_out = ctx.outputs.lib

   emit_go_link_action(
     ctx, lib_result.transitive_go_library_object, lib_out, executable)

   runfiles = ctx.runfiles(collect_data = True,
                           files = ctx.files.data)
   return struct(files = set([executable]) + lib_result.files,
                 runfiles = runfiles)

 def go_test_impl(ctx):
   """go_test_impl implements go testing.

   It emits an action to run the test generator, and then compiles the
   test into a binary."""

   lib_result = go_library_impl(ctx)
   main_go = ctx.outputs.main_go
   prefix = _go_prefix(ctx)

   go_import = prefix + ctx.label.package + "/" + ctx.label.name

   args = (["--package", go_import, "--output", ctx.outputs.main_go.path] +
           cmd_helper.template(lib_result.go_sources, "%{path}"))

   inputs = list(lib_result.go_sources) + list(ctx.files.toolchain)
   ctx.action(
       inputs = inputs,
       executable = ctx.executable.test_generator,
       outputs = [main_go],
       mnemonic = "GoTestGenTest",
       arguments = args,
       env = dict(go_environment_vars(ctx), RUNDIR=ctx.label.package))

   emit_go_compile_action(
     ctx, set([main_go]), ctx.attr.deps + [lib_result], ctx.outputs.main_lib)

   emit_go_link_action(
     ctx, lib_result.transitive_go_library_object,
     ctx.outputs.main_lib, ctx.outputs.executable)

   # TODO(bazel-team): the Go tests should do a chdir to the directory
   # holding the data files, so open-source go tests continue to work
   # without code changes.
   runfiles = ctx.runfiles(collect_data = True,
                           files = ctx.files.data + [ctx.outputs.executable])
   return struct(runfiles=runfiles)

 go_library_attrs = {
     "data": attr.label_list(
         allow_files = True,
         cfg = DATA_CFG,
     ),
     "srcs": attr.label_list(allow_files = go_filetype),
     "deps": attr.label_list(
         providers = [
             "direct_deps",
             "go_library_object",
             "transitive_go_library_object",
         ],
     ),
     "toolchain": attr.label(
         default = Label("@bazel_tools//tools/build_rules/go/toolchain:toolchain"),
         allow_files = True,
         cfg = HOST_CFG,
     ),
     "go_tool": attr.label(
         default = Label("@bazel_tools//tools/build_rules/go/toolchain:go_tool"),
         single_file = True,
         allow_files = True,
         cfg = HOST_CFG,
     ),
     "library": attr.label(
         providers = ["go_sources"],
     ),
     "go_prefix": attr.label(
         providers = ["go_prefix"],
         default = Label("//:go_prefix"),
         allow_files = False,
         cfg = HOST_CFG,
     ),
 }

 go_library_outputs = {
     "lib": "%{name}.a",
 }

 go_library = rule(
     go_library_impl,
     attrs = go_library_attrs,
     fragments = ["cpp"],
     outputs = go_library_outputs,
 )

 go_binary = rule(
     go_binary_impl,
     attrs = go_library_attrs + {
         "stamp": attr.bool(default = False),
     },
     executable = True,
     fragments = ["cpp"],
     outputs = go_library_outputs,
 )

 go_test = rule(
     go_test_impl,
     attrs = go_library_attrs + {
         "test_generator": attr.label(
             executable = True,
             default = Label(
                 "@bazel_tools//tools/build_rules/go/tools:generate_test_main"),
             cfg = HOST_CFG,
         ),
     },
     executable = True,
     fragments = ["cpp"],
     outputs = {
         "lib": "%{name}.a",
         "main_lib": "%{name}_main_test.a",
         "main_go": "%{name}_main_test.go",
     },
     test = True,
 )

 GO_TOOLCHAIN_BUILD_FILE = """
 package(
   default_visibility = [ "//visibility:public" ])

 filegroup(
   name = "toolchain",
   srcs = glob(["go/bin/*", "go/pkg/**", ]),
 )

 filegroup(
   name = "go_tool",
   srcs = [ "go/bin/go" ],
 )
 """

 def go_repositories():
   native.new_http_archive(
     name=  "golang_linux_amd64",
     url = "https://storage.googleapis.com/golang/go1.5.1.linux-amd64.tar.gz",
     build_file_content = GO_TOOLCHAIN_BUILD_FILE,
     sha256 = "2593132ca490b9ee17509d65ee2cd078441ff544899f6afb97a03d08c25524e7"
   )

   native.new_http_archive(
     name=  "golang_darwin_amd64",
     url = "https://storage.googleapis.com/golang/go1.5.1.darwin-amd64.tar.gz",
     build_file_content = GO_TOOLCHAIN_BUILD_FILE,
     sha256 = "e94487b8cd2e0239f27dc51e6c6464383b10acb491f753584605e9b28abf48fb"
   )
	# Copyright 2014 The Bazel Authors. 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.

	"""These are bare-bones Go rules.

	In order of priority:

	- No support for build tags

	- BUILD file must be written by hand.

	- No C++ interop (SWIG, cgo).

	- No test sharding or test XML.

	"""

	_DEFAULT_LIB = "go_default_library"

	_VENDOR_PREFIX = "/vendor/"

	go_filetype = FileType([".go"])

	################

	# In Go, imports are always fully qualified with a URL,
	# eg. github.com/user/project. Hence, a label //foo:bar from within a
	# Bazel workspace must be referred to as
	# "github.com/user/project/foo/bar". To make this work, each rule must
	# know the repository's URL. This is achieved, by having all go rules
	# depend on a globally unique target that has a "go_prefix" transitive
	# info provider.

	def _go_prefix_impl(ctx):
	"""go_prefix_impl provides the go prefix to use as a transitive info provider."""
	return struct(go_prefix = ctx.attr.prefix)

	def _go_prefix(ctx):
	"""slash terminated go-prefix"""
	prefix = ctx.attr.go_prefix.go_prefix
	if prefix != "" and not prefix.endswith("/"):
	prefix = prefix + "/"
	return prefix

	_go_prefix_rule = rule(
	_go_prefix_impl,
	attrs = {
	"prefix": attr.string(mandatory = True),
	},
	)

	def go_prefix(prefix):
	"""go_prefix sets the Go import name to be used for this workspace."""
	_go_prefix_rule(name = "go_prefix",
	prefix = prefix,
	visibility = ["//visibility:public" ]
	)

	################

	# TODO(bazel-team): it would be nice if Bazel had this built-in.
	def symlink_tree_commands(dest_dir, artifact_dict):
	"""Symlink_tree_commands returns a list of commands to create the
	dest_dir, and populate it according to the given dict.

	Args:
	dest_dir: The destination directory, a string.
	artifact_dict: The mapping of exec-path => path in the dest_dir.

	Returns:
	A list of commands that will setup the symlink tree.
	"""
	cmds = [
	"rm -rf " + dest_dir,
	"mkdir -p " + dest_dir,
	]

	for old_path, new_path in artifact_dict.items():
	new_dir = new_path[:new_path.rfind('/')]
	up = (new_dir.count('/') + 1 +
	dest_dir.count('/') + 1)
	cmds += [
	"mkdir -p %s/%s" % (dest_dir, new_dir),
	"ln -s %s%s %s/%s" % ('../' * up, old_path, dest_dir, new_path),
	]
	return cmds

	def go_environment_vars(ctx):
	"""Return a map of environment variables for use with actions, based on
	the arguments. Uses the ctx.fragments.cpp.cpu attribute, if present,
	and picks a default of target_os="linux" and target_arch="amd64"
	otherwise.

	Args:
	The skylark Context.

	Returns:
	A dict of environment variables for running Go tool commands that build for
	the target OS and architecture.
	"""
	bazel_to_go_toolchain = {"k8": {"GOOS": "linux",
	"GOARCH": "amd64"},
	"piii": {"GOOS": "linux",
	"GOARCH": "386"},
	"darwin": {"GOOS": "darwin",
	"GOARCH": "amd64"},
	"freebsd": {"GOOS": "freebsd",
	"GOARCH": "amd64"},
	"armeabi-v7a": {"GOOS": "linux",
	"GOARCH": "arm"},
	"arm": {"GOOS": "linux",
	"GOARCH": "arm"}}
	return bazel_to_go_toolchain.get(ctx.fragments.cpp.cpu,
	{"GOOS": "linux",
	"GOARCH": "amd64"})

	def emit_go_compile_action(ctx, sources, deps, out_lib):
	"""Construct the command line for compiling Go code.
	Constructs a symlink tree to accomodate for workspace name.

	Args:
	ctx: The skylark Context.
	sources: an iterable of source code artifacts (or CTs? or labels?)
	deps: an iterable of dependencies. Each dependency d should have an
	artifact in d.go_library_object representing an imported library.
	out_lib: the artifact (configured target?) that should be produced
	"""
	config_strip = len(ctx.configuration.bin_dir.path) + 1

	out_dir = out_lib.path + ".dir"
	out_depth = out_dir.count('/') + 1
	tree_layout = {}
	inputs = []
	prefix = _go_prefix(ctx)
	import_map = {}
	for d in deps:
	library_artifact_path = d.go_library_object.path[config_strip:]
	tree_layout[d.go_library_object.path] = prefix + library_artifact_path
	inputs += [d.go_library_object]

	source_import = prefix + d.label.package + "/" + d.label.name
	actual_import = prefix + d.label.package + "/" + d.label.name
	if d.label.name == _DEFAULT_LIB:
	source_import = prefix + d.label.package

	if source_import.rfind(_VENDOR_PREFIX) != -1:
	source_import = source_import[len(_VENDOR_PREFIX) + source_import.rfind(_VENDOR_PREFIX):]

	if source_import != actual_import:
	if source_import in import_map:
	fail("duplicate import %s: adding %s and have %s"
	% (source_import, actual_import, import_map[source_import]))
	import_map[source_import] = actual_import

	inputs += list(sources)
	for s in sources:
	tree_layout[s.path] = prefix + s.path

	cmds = symlink_tree_commands(out_dir, tree_layout)
	args = [
	"cd ", out_dir, "&&",
	('../' * out_depth) + ctx.file.go_tool.path,
	"tool", "compile",
	"-o", ('../' * out_depth) + out_lib.path, "-pack",

	# Import path.
	"-I", "."] + [
	"-importmap=%s=%s" % (k,v) for k, v in import_map.items()
	]

	# Set -p to the import path of the library, ie.
	# (ctx.label.package + "/" ctx.label.name) for now.
	cmds += [ "export GOROOT=$(pwd)/" + ctx.file.go_tool.dirname + "/..",
	' '.join(args + cmd_helper.template(sources, prefix + "%{path}"))]

	ctx.action(
	inputs = inputs + ctx.files.toolchain,
	outputs = [out_lib],
	mnemonic = "GoCompile",
	command = " && ".join(cmds),
	env = go_environment_vars(ctx))

	def go_library_impl(ctx):
	"""Implements the go_library() rule."""

	sources = set(ctx.files.srcs)
	deps = ctx.attr.deps
	if ctx.attr.library:
	sources += ctx.attr.library.go_sources
	deps += ctx.attr.library.direct_deps

	if not sources:
	fail("may not be empty", "srcs")

	out_lib = ctx.outputs.lib
	emit_go_compile_action(ctx, set(sources), deps, out_lib)

	transitive_libs = set([out_lib])
	for dep in ctx.attr.deps:
	transitive_libs += dep.transitive_go_library_object

	runfiles = ctx.runfiles(collect_data = True)
	return struct(
	label = ctx.label,
	files = set([out_lib]),
	direct_deps = deps,
	runfiles = runfiles,
	go_sources = sources,
	go_library_object = out_lib,
	transitive_go_library_object = transitive_libs)

	def emit_go_link_action(ctx, transitive_libs, lib, executable):
	"""Sets up a symlink tree to libraries to link together."""
	out_dir = executable.path + ".dir"
	out_depth = out_dir.count('/') + 1
	tree_layout = {}

	config_strip = len(ctx.configuration.bin_dir.path) + 1
	prefix = _go_prefix(ctx)

	for l in transitive_libs:
	library_artifact_path = l.path[config_strip:]
	tree_layout[l.path] = prefix + library_artifact_path

	tree_layout[lib.path] = prefix + lib.path[config_strip:]
	tree_layout[executable.path] = prefix + executable.path[config_strip:]

	cmds = symlink_tree_commands(out_dir, tree_layout)
	cmds += [
	"export GOROOT=$(pwd)/" + ctx.file.go_tool.dirname + "/..",
	"cd " + out_dir,
	' '.join([
	('../' * out_depth) + ctx.file.go_tool.path,
	"tool", "link", "-L", ".",
	"-o", prefix + executable.path[config_strip:],
	prefix + lib.path[config_strip:]])]

	ctx.action(
	inputs = list(transitive_libs) + [lib] + ctx.files.toolchain,
	outputs = [executable],
	command = ' && '.join(cmds),
	mnemonic = "GoLink",
	env = go_environment_vars(ctx))

	def go_binary_impl(ctx):
	"""go_binary_impl emits actions for compiling and linking a go executable."""
	lib_result = go_library_impl(ctx)
	executable = ctx.outputs.executable
	lib_out = ctx.outputs.lib

	emit_go_link_action(
	ctx, lib_result.transitive_go_library_object, lib_out, executable)

	runfiles = ctx.runfiles(collect_data = True,
	files = ctx.files.data)
	return struct(files = set([executable]) + lib_result.files,
	runfiles = runfiles)

	def go_test_impl(ctx):
	"""go_test_impl implements go testing.

	It emits an action to run the test generator, and then compiles the
	test into a binary."""

	lib_result = go_library_impl(ctx)
	main_go = ctx.outputs.main_go
	prefix = _go_prefix(ctx)

	go_import = prefix + ctx.label.package + "/" + ctx.label.name

	args = (["--package", go_import, "--output", ctx.outputs.main_go.path] +
	cmd_helper.template(lib_result.go_sources, "%{path}"))

	inputs = list(lib_result.go_sources) + list(ctx.files.toolchain)
	ctx.action(
	inputs = inputs,
	executable = ctx.executable.test_generator,
	outputs = [main_go],
	mnemonic = "GoTestGenTest",
	arguments = args,
	env = dict(go_environment_vars(ctx), RUNDIR=ctx.label.package))

	emit_go_compile_action(
	ctx, set([main_go]), ctx.attr.deps + [lib_result], ctx.outputs.main_lib)

	emit_go_link_action(
	ctx, lib_result.transitive_go_library_object,
	ctx.outputs.main_lib, ctx.outputs.executable)

	# TODO(bazel-team): the Go tests should do a chdir to the directory
	# holding the data files, so open-source go tests continue to work
	# without code changes.
	runfiles = ctx.runfiles(collect_data = True,
	files = ctx.files.data + [ctx.outputs.executable])
	return struct(runfiles=runfiles)

	go_library_attrs = {
	"data": attr.label_list(
	allow_files = True,
	cfg = DATA_CFG,
	),
	"srcs": attr.label_list(allow_files = go_filetype),
	"deps": attr.label_list(
	providers = [
	"direct_deps",
	"go_library_object",
	"transitive_go_library_object",
	],
	),
	"toolchain": attr.label(
	default = Label("@bazel_tools//tools/build_rules/go/toolchain:toolchain"),
	allow_files = True,
	cfg = HOST_CFG,
	),
	"go_tool": attr.label(
	default = Label("@bazel_tools//tools/build_rules/go/toolchain:go_tool"),
	single_file = True,
	allow_files = True,
	cfg = HOST_CFG,
	),
	"library": attr.label(
	providers = ["go_sources"],
	),
	"go_prefix": attr.label(
	providers = ["go_prefix"],
	default = Label("//:go_prefix"),
	allow_files = False,
	cfg = HOST_CFG,
	),
	}

	go_library_outputs = {
	"lib": "%{name}.a",
	}

	go_library = rule(
	go_library_impl,
	attrs = go_library_attrs,
	fragments = ["cpp"],
	outputs = go_library_outputs,
	)

	go_binary = rule(
	go_binary_impl,
	attrs = go_library_attrs + {
	"stamp": attr.bool(default = False),
	},
	executable = True,
	fragments = ["cpp"],
	outputs = go_library_outputs,
	)

	go_test = rule(
	go_test_impl,
	attrs = go_library_attrs + {
	"test_generator": attr.label(
	executable = True,
	default = Label(
	"@bazel_tools//tools/build_rules/go/tools:generate_test_main"),
	cfg = HOST_CFG,
	),
	},
	executable = True,
	fragments = ["cpp"],
	outputs = {
	"lib": "%{name}.a",
	"main_lib": "%{name}_main_test.a",
	"main_go": "%{name}_main_test.go",
	},
	test = True,
	)

	GO_TOOLCHAIN_BUILD_FILE = """
	package(
	default_visibility = [ "//visibility:public" ])

	filegroup(
	name = "toolchain",
	srcs = glob(["go/bin/", "go/pkg/*", ]),
	)

	filegroup(
	name = "go_tool",
	srcs = [ "go/bin/go" ],
	)
	"""

	def go_repositories():
	native.new_http_archive(
	name= "golang_linux_amd64",
	url = "https://storage.googleapis.com/golang/go1.5.1.linux-amd64.tar.gz",
	build_file_content = GO_TOOLCHAIN_BUILD_FILE,
	sha256 = "2593132ca490b9ee17509d65ee2cd078441ff544899f6afb97a03d08c25524e7"
	)

	native.new_http_archive(
	name= "golang_darwin_amd64",
	url = "https://storage.googleapis.com/golang/go1.5.1.darwin-amd64.tar.gz",
	build_file_content = GO_TOOLCHAIN_BUILD_FILE,
	sha256 = "e94487b8cd2e0239f27dc51e6c6464383b10acb491f753584605e9b28abf48fb"
	)