Add missing defaults for cc_toolchain

BEGIN_PUBLIC

Add missing defaults for cc_toolchain

Fixes breakage caused by fully enumerating known attributes of a cc_toolchain without providing default values for optional arguments.

END_PUBLIC

PiperOrigin-RevId: 684719429
Change-Id: I8d031a344a65218fc925025cfef7768d123ad879

Author: Googler

cc/toolchains/toolchain.bzl

@@ -55,16 +55,16 @@ _LEGACY_FILE_GROUPS = {
 def cc_toolchain(
         *,
         name,
-        tool_map,
-        args,
-        known_features,
-        enabled_features,
-        libc_top,
-        module_map,
-        dynamic_runtime_lib,
-        static_runtime_lib,
-        supports_header_parsing,
-        supports_param_files,
+        tool_map = None,
+        args = [],
+        known_features = [],
+        enabled_features = [],
+        libc_top = None,
+        module_map = None,
+        dynamic_runtime_lib = None,
+        static_runtime_lib = None,
+        supports_header_parsing = False,
+        supports_param_files = False,
         **kwargs):
     """A C/C++ toolchain configuration.
 

docs/toolchain_api.md

@@ -729,16 +729,16 @@ Generated rules:
 | Name  | Description | Default Value |
 | :------------- | :------------- | :------------- |
 | <a id="cc_toolchain-name"></a>name |  (str) The name of the label for the toolchain.   |  none |
-| <a id="cc_toolchain-tool_map"></a>tool_map |  (Label) The [`cc_tool_map`](#cc_tool_map) that specifies the tools to use for various toolchain actions.   |  none |
-| <a id="cc_toolchain-args"></a>args |  (List[Label]) A list of [`cc_args`](#cc_args) and `cc_arg_list` to apply across this toolchain.   |  none |
-| <a id="cc_toolchain-known_features"></a>known_features |  (List[Label]) A list of [`cc_feature`](#cc_feature) rules that this toolchain supports. Whether or not these [features](https://bazel.build/docs/cc-toolchain-config-reference#features) are enabled may change over the course of a build. See the documentation for [`cc_feature`](#cc_feature) for more information.   |  none |
-| <a id="cc_toolchain-enabled_features"></a>enabled_features |  (List[Label]) A list of [`cc_feature`](#cc_feature) rules whose initial state should be `enabled`. Note that it is still possible for these [features](https://bazel.build/docs/cc-toolchain-config-reference#features) to be disabled over the course of a build through other mechanisms. See the documentation for [`cc_feature`](#cc_feature) for more information.   |  none |
-| <a id="cc_toolchain-libc_top"></a>libc_top |  (Label) A collection of artifacts for libc passed as inputs to compile/linking actions. See [`cc_toolchain.libc_top`](https://bazel.build/reference/be/c-cpp#cc_toolchain.libc_top) for more information.   |  none |
-| <a id="cc_toolchain-module_map"></a>module_map |  (Label) Module map artifact to be used for modular builds. See [`cc_toolchain.module_map`](https://bazel.build/reference/be/c-cpp#cc_toolchain.module_map) for more information.   |  none |
-| <a id="cc_toolchain-dynamic_runtime_lib"></a>dynamic_runtime_lib |  (Label) Dynamic library to link when the `static_link_cpp_runtimes` and `dynamic_linking_mode` [features](https://bazel.build/docs/cc-toolchain-config-reference#features) are both enabled. See [`cc_toolchain.dynamic_runtime_lib`](https://bazel.build/reference/be/c-cpp#cc_toolchain.dynamic_runtime_lib) for more information.   |  none |
-| <a id="cc_toolchain-static_runtime_lib"></a>static_runtime_lib |  (Label) Static library to link when the `static_link_cpp_runtimes` and `static_linking_mode` [features](https://bazel.build/docs/cc-toolchain-config-reference#features) are both enabled. See [`cc_toolchain.dynamic_runtime_lib`](https://bazel.build/reference/be/c-cpp#cc_toolchain.dynamic_runtime_lib) for more information.   |  none |
-| <a id="cc_toolchain-supports_header_parsing"></a>supports_header_parsing |  (bool) Whether or not this toolchain supports header parsing actions. See [`cc_toolchain.supports_header_parsing`](https://bazel.build/reference/be/c-cpp#cc_toolchain.supports_header_parsing) for more information.   |  none |
-| <a id="cc_toolchain-supports_param_files"></a>supports_param_files |  (bool) Whether or not this toolchain supports linking via param files. See [`cc_toolchain.supports_param_files`](https://bazel.build/reference/be/c-cpp#cc_toolchain.supports_param_files) for more information.   |  none |
+| <a id="cc_toolchain-tool_map"></a>tool_map |  (Label) The [`cc_tool_map`](#cc_tool_map) that specifies the tools to use for various toolchain actions.   |  `None` |
+| <a id="cc_toolchain-args"></a>args |  (List[Label]) A list of [`cc_args`](#cc_args) and `cc_arg_list` to apply across this toolchain.   |  `[]` |
+| <a id="cc_toolchain-known_features"></a>known_features |  (List[Label]) A list of [`cc_feature`](#cc_feature) rules that this toolchain supports. Whether or not these [features](https://bazel.build/docs/cc-toolchain-config-reference#features) are enabled may change over the course of a build. See the documentation for [`cc_feature`](#cc_feature) for more information.   |  `[]` |
+| <a id="cc_toolchain-enabled_features"></a>enabled_features |  (List[Label]) A list of [`cc_feature`](#cc_feature) rules whose initial state should be `enabled`. Note that it is still possible for these [features](https://bazel.build/docs/cc-toolchain-config-reference#features) to be disabled over the course of a build through other mechanisms. See the documentation for [`cc_feature`](#cc_feature) for more information.   |  `[]` |
+| <a id="cc_toolchain-libc_top"></a>libc_top |  (Label) A collection of artifacts for libc passed as inputs to compile/linking actions. See [`cc_toolchain.libc_top`](https://bazel.build/reference/be/c-cpp#cc_toolchain.libc_top) for more information.   |  `None` |
+| <a id="cc_toolchain-module_map"></a>module_map |  (Label) Module map artifact to be used for modular builds. See [`cc_toolchain.module_map`](https://bazel.build/reference/be/c-cpp#cc_toolchain.module_map) for more information.   |  `None` |
+| <a id="cc_toolchain-dynamic_runtime_lib"></a>dynamic_runtime_lib |  (Label) Dynamic library to link when the `static_link_cpp_runtimes` and `dynamic_linking_mode` [features](https://bazel.build/docs/cc-toolchain-config-reference#features) are both enabled. See [`cc_toolchain.dynamic_runtime_lib`](https://bazel.build/reference/be/c-cpp#cc_toolchain.dynamic_runtime_lib) for more information.   |  `None` |
+| <a id="cc_toolchain-static_runtime_lib"></a>static_runtime_lib |  (Label) Static library to link when the `static_link_cpp_runtimes` and `static_linking_mode` [features](https://bazel.build/docs/cc-toolchain-config-reference#features) are both enabled. See [`cc_toolchain.dynamic_runtime_lib`](https://bazel.build/reference/be/c-cpp#cc_toolchain.dynamic_runtime_lib) for more information.   |  `None` |
+| <a id="cc_toolchain-supports_header_parsing"></a>supports_header_parsing |  (bool) Whether or not this toolchain supports header parsing actions. See [`cc_toolchain.supports_header_parsing`](https://bazel.build/reference/be/c-cpp#cc_toolchain.supports_header_parsing) for more information.   |  `False` |
+| <a id="cc_toolchain-supports_param_files"></a>supports_param_files |  (bool) Whether or not this toolchain supports linking via param files. See [`cc_toolchain.supports_param_files`](https://bazel.build/reference/be/c-cpp#cc_toolchain.supports_param_files) for more information.   |  `False` |
 | <a id="cc_toolchain-kwargs"></a>kwargs |  [common attributes](https://bazel.build/reference/be/common-definitions#common-attributes) that should be applied to all rules created by this macro.   |  none |