Rename host_go{arch,os} to exec_ (#4525)

This is technically more correct as these may be selected on non-host
exec platforms

Author: dzbarsky

go/private/BUILD.sdk.bazel

@@ -109,7 +109,7 @@ package_list(
 
 declare_go_toolchains(
     builder = ":builder_reset",
-    host_goos = "{goos}",
+    exec_goos = "{goos}",
     pack = ":pack_reset",
     sdk = ":go_sdk",
 )

go/private/go_toolchain.bzl

@@ -96,7 +96,7 @@ go_toolchain = rule(
     provides = [platform_common.ToolchainInfo],
 )
 
-def declare_go_toolchains(host_goos, sdk, builder, pack):
+def declare_go_toolchains(exec_goos, sdk, builder, pack):
     """Declares go_toolchain targets for each platform."""
     for p in PLATFORMS:
         if p.cgo:
@@ -107,9 +107,9 @@ def declare_go_toolchains(host_goos, sdk, builder, pack):
 
         link_flags = []
         cgo_link_flags = []
-        if host_goos == "darwin":
+        if exec_goos == "darwin":
             cgo_link_flags.extend(["-shared", "-Wl,-all_load"])
-        if host_goos == "linux":
+        elif exec_goos == "linux":
             cgo_link_flags.append("-Wl,-whole-archive")
 
         go_toolchain(
@@ -128,8 +128,8 @@ def declare_go_toolchains(host_goos, sdk, builder, pack):
 def declare_bazel_toolchains(
         *,
         go_toolchain_repo,
-        host_goarch,
-        host_goos,
+        exec_goarch,
+        exec_goos,
         major,
         minor,
         patch,
@@ -260,8 +260,8 @@ def declare_bazel_toolchains(
             name = prefix + "go_" + p.name,
             toolchain_type = GO_TOOLCHAIN,
             exec_compatible_with = [
-                "@io_bazel_rules_go//go/toolchain:" + host_goos,
-                "@io_bazel_rules_go//go/toolchain:" + host_goarch,
+                "@io_bazel_rules_go//go/toolchain:" + exec_goos,
+                "@io_bazel_rules_go//go/toolchain:" + exec_goarch,
             ],
             target_compatible_with = constraints,
             target_settings = [

go/private/sdk.bzl

@@ -211,8 +211,8 @@ def go_toolchains_single_definition(ctx, *, prefix, goos, goarch, sdk_repo, sdk_
     chunks.append("""declare_bazel_toolchains(
     prefix = "{prefix}",
     go_toolchain_repo = "@{sdk_repo}",
-    host_goarch = "{goarch}",
-    host_goos = "{goos}",
+    exec_goarch = "{goarch}",
+    exec_goos = "{goos}",
     major = {identifier_prefix}MAJOR_VERSION,
     minor = {identifier_prefix}MINOR_VERSION,
     patch = {identifier_prefix}PATCH_VERSION,

tests/core/starlark/sdk_tests.bzl

@@ -24,8 +24,8 @@ _123_PREFIX_PRERELEASE_SUFFIX = "rc1"
         """declare_bazel_toolchains(
     prefix = "123_prefix_",
     go_toolchain_repo = "@sdk_repo",
-    host_goarch = "amd64",
-    host_goos = "linux",
+    exec_goarch = "amd64",
+    exec_goos = "linux",
     major = _123_PREFIX_MAJOR_VERSION,
     minor = _123_PREFIX_MINOR_VERSION,
     patch = _123_PREFIX_PATCH_VERSION,
@@ -64,8 +64,8 @@ def _go_toolchains_single_definition_without_version_test(ctx):
         """declare_bazel_toolchains(
     prefix = "123_prefix_",
     go_toolchain_repo = "@sdk_repo",
-    host_goarch = "amd64",
-    host_goos = "linux",
+    exec_goarch = "amd64",
+    exec_goos = "linux",
     major = _123_PREFIX_MAJOR_VERSION,
     minor = _123_PREFIX_MINOR_VERSION,
     patch = _123_PREFIX_PATCH_VERSION,