platform

Author: keith

.bazelrc

@@ -52,3 +52,4 @@ build:linux --cxxopt='-std=c++14'
 build --per_file_copt="external/.*zlib.*/.*.c@-Wno-deprecated-non-prototype"
 
 build:windows --copt=-Wno-builtin-macro-redefined --host_copt=-Wno-builtin-macro-redefined
+build:windows --extra_toolchains=@local_config_cc//:cc-toolchain-x64_windows-clang-cl --extra_execution_platforms=//:windows

BUILD

@@ -15,3 +15,12 @@ filegroup(
         "//tools:for_bazel_tests",
     ],
 )
+
+platform(
+    name = "windows",
+    constraint_values = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:windows",
+        "@bazel_tools//tools/cpp:clang-cl",
+    ],
+)

MODULE.bazel

@@ -72,3 +72,6 @@ single_version_override(
     patch_strip = 1,
     patches = ["//:rules_cc.patch"],
 )
+
+cc_configure = use_extension("@rules_cc//cc:extensions.bzl", "cc_configure_extension")
+use_repo(cc_configure, "local_config_cc")

swift/toolchains/swift_toolchain.bzl

@@ -429,11 +429,11 @@ def _swift_toolchain_impl(ctx):
         target_triples.parse(ctx.var.get("CC_TARGET_TRIPLE") or target_system_name),
     )
 
-    # if "clang" not in cc_toolchain.compiler:
-    #     fail("Swift requires the configured CC toolchain to be LLVM (clang). " +
-    #          "Either use the locally installed LLVM by setting `CC=clang` in your environment " +
-    #          "before invoking Bazel, or configure a Bazel LLVM CC toolchain." +
-    #          "The current CC toolchain uses: {}".format(cc_toolchain.compiler))
+    if "clang" not in cc_toolchain.compiler:
+        fail("Swift requires the configured CC toolchain to be LLVM (clang). " +
+             "Either use the locally installed LLVM by setting `CC=clang` in your environment " +
+             "before invoking Bazel, or configure a Bazel LLVM CC toolchain." +
+             "The current CC toolchain uses: {}".format(cc_toolchain.compiler))
 
     if ctx.attr.os == "windows":
         swift_linkopts_cc_info = _swift_windows_linkopts_cc_info(