Separate String and Label declaration of go toolchain

extras/gomock.bzl

@@ -23,7 +23,7 @@
 # DO NOT USE IT.
 
 load("//go/private:context.bzl", "go_context")
-load("//go/private:common.bzl", "GO_TOOLCHAIN")
+load("//go/private:common.bzl", "GO_TOOLCHAIN", "GO_TOOLCHAIN_LABEL")
 load("//go/private/rules:wrappers.bzl", go_binary = "go_binary_macro")
 load("//go/private:providers.bzl", "GoLibrary")
 load("@bazel_skylib//lib:paths.bzl", "paths")
@@ -79,7 +79,7 @@ def _gomock_source_impl(ctx):
             ctx.file.mockgen_tool,
             go_ctx.go,
         ],
-        toolchain = GO_TOOLCHAIN,
+        toolchain = GO_TOOLCHAIN_LABEL,
         command = """
             export GOPATH=$(pwd)/{gopath} &&
             {cmd} {args} > {out}

go/private/actions/compilepkg.bzl

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-load("//go/private:common.bzl", "GO_TOOLCHAIN")
+load("//go/private:common.bzl", "GO_TOOLCHAIN_LABEL")
 load(
     "//go/private:mode.bzl",
     "link_mode_args",
@@ -163,5 +163,5 @@ def emit_compilepkg(
         executable = go.toolchain._builder,
         arguments = [args],
         env = go.env,
-        toolchain = GO_TOOLCHAIN,
+        toolchain = GO_TOOLCHAIN_LABEL,
     )

go/private/actions/link.bzl

@@ -14,7 +14,7 @@
 
 load(
     "//go/private:common.bzl",
-    "GO_TOOLCHAIN",
+    "GO_TOOLCHAIN_LABEL",
     "as_set",
     "count_group_matches",
     "has_shared_lib_extension",
@@ -210,7 +210,7 @@ def emit_link(
         executable = go.toolchain._builder,
         arguments = [builder_args, "--", tool_args],
         env = go.env,
-        toolchain = GO_TOOLCHAIN,
+        toolchain = GO_TOOLCHAIN_LABEL,
     )
 
 def _extract_extldflags(gc_linkopts, extldflags):

go/private/actions/stdlib.bzl

@@ -15,7 +15,7 @@
 load(
     "//go/private:common.bzl",
     "COVERAGE_OPTIONS_DENYLIST",
-    "GO_TOOLCHAIN",
+    "GO_TOOLCHAIN_LABEL",
 )
 load(
     "//go/private:providers.bzl",
@@ -83,7 +83,7 @@ def _build_stdlib_list_json(go):
         executable = go.toolchain._builder,
         arguments = [args],
         env = _build_env(go),
-        toolchain = GO_TOOLCHAIN,
+        toolchain = GO_TOOLCHAIN_LABEL,
     )
     return out
 
@@ -151,7 +151,7 @@ def _build_stdlib(go):
         executable = go.toolchain._builder,
         arguments = [args],
         env = _build_env(go),
-        toolchain = GO_TOOLCHAIN,
+        toolchain = GO_TOOLCHAIN_LABEL,
     )
     return GoStdLib(
         _list_json = _build_stdlib_list_json(go),

go/private/common.bzl

@@ -12,7 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-GO_TOOLCHAIN = str(Label("@io_bazel_rules_go//go:toolchain"))
+GO_TOOLCHAIN = "@io_bazel_rules_go//go:toolchain"
+GO_TOOLCHAIN_LABEL = Label(GO_TOOLCHAIN)
 
 go_exts = [
     ".go",

go/private/rules/test.bzl

@@ -19,6 +19,7 @@ load(
 load(
     "//go/private:common.bzl",
     "GO_TOOLCHAIN",
+    "GO_TOOLCHAIN_LABEL",
     "as_list",
     "asm_exts",
     "cgo_exts",
@@ -118,7 +119,7 @@ def _go_test_impl(ctx):
         mnemonic = "GoTestGenTest",
         executable = go.toolchain._builder,
         arguments = [arguments],
-        toolchain = GO_TOOLCHAIN,
+        toolchain = GO_TOOLCHAIN_LABEL,
     )
 
     test_gc_linkopts = gc_linkopts(ctx)

proto/compiler.bzl

@@ -24,6 +24,7 @@ load(
 load(
     "//go/private:common.bzl",
     "GO_TOOLCHAIN",
+    "GO_TOOLCHAIN_LABEL",
 )
 load(
     "//go/private/rules:transition.bzl",
@@ -130,7 +131,7 @@ def go_proto_compile(go, compiler, protos, imports, importpath):
         progress_message = "Generating into %s" % go_srcs[0].dirname,
         mnemonic = "GoProtocGen",
         executable = compiler.internal.go_protoc,
-        toolchain = GO_TOOLCHAIN,
+        toolchain = GO_TOOLCHAIN_LABEL,
         arguments = [args],
         env = go.env,
         # We may need the shell environment (potentially augmented with --action_env)