Add warnings as errors cc feature

This PR adds a `feature` to cc toolchains to treat warnings as errors. The `feature` is disabled by default.

Closes #11550

Closes #13927.

PiperOrigin-RevId: 423364251

Author: jheaff1

tools/cpp/unix_cc_configure.bzl

@@ -532,7 +532,7 @@ def configure_unix_toolchain(repository_ctx, cpu_value, overriden_tools):
                     # We need to undef it as some distributions now have it enabled by default.
                     "-U_FORTIFY_SOURCE",
                     "-fstack-protector",
-                    # All warnings are enabled. Maybe enable -Werror as well?
+                    # All warnings are enabled.
                     "-Wall",
                     # Enable a few more warnings that aren't part of -Wall.
                 ] + ((

tools/cpp/unix_cc_toolchain_config.bzl

@@ -1182,6 +1182,20 @@ def _impl(ctx):
         ],
     )
 
+    treat_warnings_as_errors_feature = feature(
+        name = "treat_warnings_as_errors",
+        flag_sets = [
+            flag_set(
+                actions = [ACTION_NAMES.c_compile, ACTION_NAMES.cpp_compile],
+                flag_groups = [flag_group(flags = ["-Werror"])],
+            ),
+            flag_set(
+                actions = all_link_actions,
+                flag_groups = [flag_group(flags = ["-Wl,-fatal-warnings"])],
+            ),
+        ],
+    )
+
     is_linux = ctx.attr.target_libc != "macosx"
 
     # TODO(#8303): Mac crosstool should also declare every feature.
@@ -1234,6 +1248,7 @@ def _impl(ctx):
             user_compile_flags_feature,
             sysroot_feature,
             unfiltered_compile_flags_feature,
+            treat_warnings_as_errors_feature,
         ] + layering_check_features(ctx.attr.compiler)
     else:
         # macOS artifact name patterns differ from the defaults only for dynamic
@@ -1263,6 +1278,7 @@ def _impl(ctx):
             user_compile_flags_feature,
             sysroot_feature,
             unfiltered_compile_flags_feature,
+            treat_warnings_as_errors_feature,
         ] + layering_check_features(ctx.attr.compiler)
 
     return cc_common.create_cc_toolchain_config_info(

tools/cpp/windows_cc_toolchain_config.bzl

@@ -786,7 +786,7 @@ def _impl(ctx):
             name = "treat_warnings_as_errors",
             flag_sets = [
                 flag_set(
-                    actions = [ACTION_NAMES.c_compile, ACTION_NAMES.cpp_compile],
+                    actions = [ACTION_NAMES.c_compile, ACTION_NAMES.cpp_compile] + all_link_actions,
                     flag_groups = [flag_group(flags = ["/WX"])],
                 ),
             ],
@@ -1271,6 +1271,20 @@ def _impl(ctx):
                 provides = ["profile"],
             )
 
+            treat_warnings_as_errors_feature = feature(
+                name = "treat_warnings_as_errors",
+                flag_sets = [
+                    flag_set(
+                        actions = [ACTION_NAMES.c_compile, ACTION_NAMES.cpp_compile],
+                        flag_groups = [flag_group(flags = ["-Werror"])],
+                    ),
+                    flag_set(
+                        actions = all_link_actions,
+                        flag_groups = [flag_group(flags = ["-Wl,-fatal-warnings"])],
+                    ),
+                ],
+            )
+
             user_compile_flags_feature = feature(
                 name = "user_compile_flags",
                 enabled = True,
@@ -1311,6 +1325,7 @@ def _impl(ctx):
                 dbg_feature,
                 opt_feature,
                 user_compile_flags_feature,
+                treat_warnings_as_errors_feature,
                 sysroot_feature,
             ]