Refactor away references to @io_bazel_rules_go (#3185)

* Use repo-relative labels in load statements

* Introduce a constant for the Go toolchain requirement

Gets rid of a common source of repo-absolute labels. Repo-relative
labels for toolchains aren't supported with Bazel 4. Now that
config_common.toolchain_type exists, the string label may also be
replaced with a more complex Starlark type in the future.

* Use Label(...) in macros

This resolves a label literal relative to the call site of the Label
constructor.

* Use repo-relative labels in rule attribute defaults

extras/BUILD.bazel

@@ -24,7 +24,10 @@ bzl_library(
     name = "embed_data",
     srcs = ["embed_data.bzl"],
     visibility = ["//visibility:public"],
-    deps = ["@io_bazel_rules_go//go/private:context"],
+    deps = [
+        "//go/private:context",
+        "//go/private:go_toolchain",
+    ],
 )
 
 bzl_library(
@@ -41,6 +44,7 @@ bzl_library(
     visibility = ["//visibility:public"],
     deps = [
         "//go/private:context",
+        "//go/private:go_toolchain",
         "//go/private:providers",
         "//go/private/rules:wrappers",
     ],

extras/bindata.bzl

@@ -15,9 +15,13 @@
 """bindata.bzl provides the bindata rule for embedding data in .go files"""
 
 load(
-    "@io_bazel_rules_go//go:def.bzl",
+    "//go:def.bzl",
     "go_context",
 )
+load(
+    "//go/private:go_toolchain.bzl",
+    "GO_TOOLCHAIN",
+)
 
 def _bindata_impl(ctx):
     go = go_context(ctx)
@@ -78,5 +82,5 @@ bindata = rule(
             default = "//:go_context_data",
         ),
     },
-    toolchains = ["@io_bazel_rules_go//go:toolchain"],
+    toolchains = [GO_TOOLCHAIN],
 )

extras/embed_data.bzl

@@ -13,9 +13,13 @@
 # limitations under the License.
 
 load(
-    "@io_bazel_rules_go//go/private:context.bzl",  #TODO: This ought to be def
+    "//go/private:context.bzl",  #TODO: This ought to be def
     "go_context",
 )
+load(
+    "//go/private:go_toolchain.bzl",
+    "GO_TOOLCHAIN",
+)
 
 _DOC = """`go_embed_data` generates a .go file that contains data from a file or a
 list of files. It should be consumed in the srcs list of one of the
@@ -135,6 +139,6 @@ go_embed_data = rule(
             default = "//:go_context_data",
         ),
     },
-    toolchains = ["@io_bazel_rules_go//go:toolchain"],
+    toolchains = [GO_TOOLCHAIN],
 )
 # See /docs/go/extras/extras.md#go_embed_data for full documentation.

extras/embed_data_deps.bzl

@@ -26,7 +26,7 @@ def go_embed_data_dependencies():
             remote = "https://github.com/kevinburke/go-bindata",
             # v3.13.0+incompatible, "latest" as of 2019-07-08
             commit = "53d73b98acf3bd9f56d7f9136ed8e1be64756e1d",
-            patches = ["@io_bazel_rules_go//third_party:com_github_kevinburke_go_bindata-gazelle.patch"],
+            patches = [Label("//third_party:com_github_kevinburke_go_bindata-gazelle.patch")],
             patch_args = ["-p1"],
             shallow_since = "1545009224 +0000",
             # gazelle args: -go_prefix github.com/kevinburke/go-bindata

extras/gomock.bzl

@@ -23,6 +23,7 @@
 # DO NOT USE IT.
 
 load("//go/private:context.bzl", "go_context")
+load("//go/private:go_toolchain.bzl", "GO_TOOLCHAIN")
 load("//go/private/rules:wrappers.bzl", go_binary = "go_binary_macro")
 load("//go/private:providers.bzl", "GoLibrary")
 load("@bazel_skylib//lib:paths.bzl", "paths")
@@ -143,10 +144,10 @@ _gomock_source = rule(
             mandatory = False,
         ),
         "_go_context_data": attr.label(
-            default = "@io_bazel_rules_go//:go_context_data",
+            default = "//:go_context_data",
         ),
     },
-    toolchains = ["@io_bazel_rules_go//go:toolchain"],
+    toolchains = [GO_TOOLCHAIN],
 )
 
 def gomock(name, library, out, source = None, interfaces = [], package = "", self_package = "", aux_files = {}, mockgen_tool = _MOCKGEN_TOOL, imports = {}, copyright_file = None, mock_names = {}):
@@ -274,10 +275,10 @@ _gomock_prog_gen = rule(
             mandatory = False,
         ),
         "_go_context_data": attr.label(
-            default = "@io_bazel_rules_go//:go_context_data",
+            default = "//:go_context_data",
         ),
     },
-    toolchains = ["@io_bazel_rules_go//go:toolchain"],
+    toolchains = [GO_TOOLCHAIN],
 )
 
 def _gomock_prog_exec_impl(ctx):
@@ -356,10 +357,10 @@ _gomock_prog_exec = rule(
             mandatory = False,
         ),
         "_go_context_data": attr.label(
-            default = "@io_bazel_rules_go//:go_context_data",
+            default = "//:go_context_data",
         ),
     },
-    toolchains = ["@io_bazel_rules_go//go:toolchain"],
+    toolchains = [GO_TOOLCHAIN],
 )
 
 def _handle_shared_args(ctx, args):

go/private/BUILD.bazel

@@ -57,6 +57,7 @@ bzl_library(
         ":mode",
         ":providers",
         "//go/platform:apple",
+        "//go/private:go_toolchain",
         "//go/private/rules:transition",
         "@bazel_skylib//lib:paths",
         "@bazel_skylib//rules:common_settings",
@@ -68,7 +69,10 @@ bzl_library(
 bzl_library(
     name = "go_toolchain",
     srcs = ["go_toolchain.bzl"],
-    visibility = ["//go:__subpackages__"],
+    visibility = [
+        "//extras:__pkg__",  # Manually added
+        "//go:__subpackages__",
+    ],
     deps = [
         "//go/private:platforms",
         "//go/private:providers",

go/private/context.bzl

@@ -26,6 +26,10 @@ load(
     "OBJCPP_COMPILE_ACTION_NAME",
     "OBJC_COMPILE_ACTION_NAME",
 )
+load(
+    ":go_toolchain.bzl",
+    "GO_TOOLCHAIN",
+)
 load(
     ":providers.bzl",
     "CgoContextInfo",
@@ -354,7 +358,7 @@ def go_context(ctx, attr = None):
     """
     if not attr:
         attr = ctx.attr
-    toolchain = ctx.toolchains["@io_bazel_rules_go//go:toolchain"]
+    toolchain = ctx.toolchains[GO_TOOLCHAIN]
     cgo_context_info = None
     go_config_info = None
     stdlib = None
@@ -546,7 +550,7 @@ go_context_data = rule(
     },
     doc = """go_context_data gathers information about the build configuration.
     It is a common dependency of all Go targets.""",
-    toolchains = ["@io_bazel_rules_go//go:toolchain"],
+    toolchains = [GO_TOOLCHAIN],
     cfg = request_nogo_transition,
 )
 

go/private/go_toolchain.bzl

@@ -25,6 +25,8 @@ load("//go/private/actions:link.bzl", "emit_link")
 load("//go/private/actions:pack.bzl", "emit_pack")
 load("//go/private/actions:stdlib.bzl", "emit_stdlib")
 
+GO_TOOLCHAIN = "@io_bazel_rules_go//go:toolchain"
+
 def _go_toolchain_impl(ctx):
     sdk = ctx.attr.sdk[GoSDK]
     cross_compile = ctx.attr.goos != sdk.goos or ctx.attr.goarch != sdk.goarch
@@ -131,7 +133,7 @@ def declare_toolchains(host, sdk, builder):
         )
         native.toolchain(
             name = toolchain_name,
-            toolchain_type = "@io_bazel_rules_go//go:toolchain",
+            toolchain_type = GO_TOOLCHAIN,
             exec_compatible_with = [
                 "@io_bazel_rules_go//go/toolchain:" + host_goos,
                 "@io_bazel_rules_go//go/toolchain:" + host_goarch,

go/private/rules/binary.bzl

@@ -22,6 +22,10 @@ load(
     "cgo_exts",
     "go_exts",
 )
+load(
+    "//go/private:go_toolchain.bzl",
+    "GO_TOOLCHAIN",
+)
 load(
     "//go/private:providers.bzl",
     "GoLibrary",
@@ -380,7 +384,7 @@ _go_binary_kwargs = {
             default = "@bazel_tools//tools/allowlists/function_transition_allowlist",
         ),
     },
-    "toolchains": ["@io_bazel_rules_go//go:toolchain"],
+    "toolchains": [GO_TOOLCHAIN],
     "doc": """This builds an executable from a set of source files,
     which must all be in the `main` package. You can run the binary with
     `bazel run`, or you can build it with `bazel build` and run it directly.<br><br>

go/private/rules/info.bzl

@@ -16,6 +16,10 @@ load(
     "//go/private:context.bzl",
     "go_context",
 )
+load(
+    "//go/private:go_toolchain.bzl",
+    "GO_TOOLCHAIN",
+)
 
 def _go_info_impl(ctx):
     go = go_context(ctx)
@@ -46,7 +50,7 @@ _go_info = rule(
             default = "//:go_context_data",
         ),
     },
-    toolchains = ["@io_bazel_rules_go//go:toolchain"],
+    toolchains = [GO_TOOLCHAIN],
 )
 
 def go_info():

go/private/rules/library.bzl

@@ -22,6 +22,10 @@ load(
     "//go/private:context.bzl",
     "go_context",
 )
+load(
+    "//go/private:go_toolchain.bzl",
+    "GO_TOOLCHAIN",
+)
 load(
     "//go/private:providers.bzl",
     "GoLibrary",
@@ -176,7 +180,7 @@ go_library = rule(
             default = "@bazel_tools//tools/allowlists/function_transition_allowlist",
         ),
     },
-    toolchains = ["@io_bazel_rules_go//go:toolchain"],
+    toolchains = [GO_TOOLCHAIN],
     doc = """This builds a Go library from a set of source files that are all part of
     the same package.<br><br>
     ***Note:*** For targets generated by Gazelle, `name` is typically the last component of the path,
@@ -207,7 +211,7 @@ go_tool_library = rule(
         "_cgo_context_data": attr.label(default = "//:cgo_context_data_proxy"),
         "_stdlib": attr.label(default = "//:stdlib"),
     },
-    toolchains = ["@io_bazel_rules_go//go:toolchain"],
+    toolchains = [GO_TOOLCHAIN],
 )
 # This is used instead of `go_library` for dependencies of the `nogo` rule and
 # packages that are depended on implicitly by code generated within the Go rules.

go/private/rules/nogo.bzl

@@ -16,6 +16,10 @@ load(
     "//go/private:context.bzl",
     "go_context",
 )
+load(
+    "//go/private:go_toolchain.bzl",
+    "GO_TOOLCHAIN",
+)
 load(
     "//go/private:providers.bzl",
     "EXPORT_PATH",
@@ -102,7 +106,7 @@ _nogo = rule(
             default = "@bazel_tools//tools/whitelists/function_transition_whitelist",
         ),
     },
-    toolchains = ["@io_bazel_rules_go//go:toolchain"],
+    toolchains = [GO_TOOLCHAIN],
     cfg = go_tool_transition,
 )
 

go/private/rules/source.bzl

@@ -16,6 +16,10 @@ load(
     "//go/private:context.bzl",
     "go_context",
 )
+load(
+    "//go/private:go_toolchain.bzl",
+    "GO_TOOLCHAIN",
+)
 load(
     "//go/private:providers.bzl",
     "GoLibrary",
@@ -78,7 +82,7 @@ go_source = rule(
         "_go_config": attr.label(default = "//:go_config"),
         "_cgo_context_data": attr.label(default = "//:cgo_context_data_proxy"),
     },
-    toolchains = ["@io_bazel_rules_go//go:toolchain"],
+    toolchains = [GO_TOOLCHAIN],
     doc = """This declares a set of source files and related dependencies that can be embedded into one of the
     other rules.
     This is used as a way of easily declaring a common set of sources re-used in multiple rules.<br><br>

go/private/rules/stdlib.bzl

@@ -16,6 +16,10 @@ load(
     "//go/private:context.bzl",
     "go_context",
 )
+load(
+    "//go/private:go_toolchain.bzl",
+    "GO_TOOLCHAIN",
+)
 load(
     "//go/private:providers.bzl",
     "CgoContextInfo",
@@ -38,5 +42,5 @@ stdlib = rule(
     },
     doc = """stdlib builds the standard library for the target configuration
 or uses the precompiled standard library from the SDK if it is suitable.""",
-    toolchains = ["@io_bazel_rules_go//go:toolchain"],
+    toolchains = [GO_TOOLCHAIN],
 )

go/private/rules/test.bzl

@@ -25,6 +25,10 @@ load(
     "pkg_dir",
     "split_srcs",
 )
+load(
+    "//go/private:go_toolchain.bzl",
+    "GO_TOOLCHAIN",
+)
 load(
     "//go/private/rules:binary.bzl",
     "gc_linkopts",
@@ -415,7 +419,7 @@ _go_test_kwargs = {
     },
     "executable": True,
     "test": True,
-    "toolchains": ["@io_bazel_rules_go//go:toolchain"],
+    "toolchains": [GO_TOOLCHAIN],
     "doc": """This builds a set of tests that can be run with `bazel test`.<br><br>
     To run all tests in the workspace, and print output on failure (the
     equivalent of `go test ./...`), run<br>

go/tools/bazel_testing/def.bzl

@@ -21,7 +21,7 @@ def go_bazel_test(rule_files = None, **kwargs):
     """
 
     if not rule_files:
-        rule_files = ["@io_bazel_rules_go//:all_files"]
+        rule_files = [Label("//:all_files")]
 
     # Add dependency on bazel_testing library.
     kwargs.setdefault("deps", [])

proto/compiler.bzl

@@ -21,6 +21,10 @@ load(
     "GoLibrary",
     "go_context",
 )
+load(
+    "//go/private:go_toolchain.bzl",
+    "GO_TOOLCHAIN",
+)
 load(
     "//go/private/rules:transition.bzl",
     "go_reset_target",
@@ -206,7 +210,7 @@ _go_proto_compiler = rule(
             default = "//:go_context_data",
         ),
     },
-    toolchains = ["@io_bazel_rules_go//go:toolchain"],
+    toolchains = [GO_TOOLCHAIN],
 )
 
 def go_proto_compiler(name, **kwargs):

proto/def.bzl

@@ -27,6 +27,10 @@ load(
     "GoProtoCompiler",
     "proto_path",
 )
+load(
+    "//go/private:go_toolchain.bzl",
+    "GO_TOOLCHAIN",
+)
 load(
     "//go/private:providers.bzl",
     "INFERRED_PATH",
@@ -178,14 +182,14 @@ go_proto_library = rule(
             default = "@bazel_tools//tools/allowlists/function_transition_allowlist",
         ),
     },
-    toolchains = ["@io_bazel_rules_go//go:toolchain"],
+    toolchains = [GO_TOOLCHAIN],
 )
 # go_proto_library is a rule that takes a proto_library (in the proto
 # attribute) and produces a go library for it.
 
 def go_grpc_library(**kwargs):
     # TODO: Deprecate once gazelle generates just go_proto_library
-    go_proto_library(compilers = ["@io_bazel_rules_go//proto:go_grpc"], **kwargs)
+    go_proto_library(compilers = [Label("//proto:go_grpc")], **kwargs)
 
 def proto_register_toolchains():
     print("You no longer need to call proto_register_toolchains(), it does nothing")