add windows builds to bazel

Author: anonrig

.bazelrc

@@ -1 +1,8 @@
-build --cxxopt="-std=c++20"
+common --enable_platform_specific_config
+build --verbose_failures
+
+build:unix --cxxopt="-std=c++20"
+
+build:windows --extra_toolchains=@local_config_cc//:cc-toolchain-x64_windows-clang-cl
+build:windows --extra_execution_platforms=//:x64_windows-clang-cl
+build:windows --cxxopt='/std:c++20' --host_cxxopt='/std:c++20'

.github/workflows/bazel.yml

@@ -22,14 +22,25 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
+  windows:
+    runs-on: windows-2025
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - uses: bazel-contrib/setup-bazel@bbf8fe8b219f642c7f8bc673215f28eb1d9dec51 # v0.10.0
+        with:
+          bazelisk-cache: true
+          disk-cache: ${{ github.workflow }}-${{ runner.os }}
+          repository-cache: true
+      - name: Build & Test
+        run: bazel test //...
   macos:
     runs-on: macos-latest
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - uses: bazel-contrib/setup-bazel@bbf8fe8b219f642c7f8bc673215f28eb1d9dec51 # v0.10.0
         with:
           bazelisk-cache: true
-          disk-cache: ${{ github.workflow }}
+          disk-cache: ${{ github.workflow }}-${{ runner.os }}
           repository-cache: true
       - name: Build & Test
         run: bazel test //...
@@ -45,7 +56,7 @@ jobs:
       - uses: bazel-contrib/setup-bazel@bbf8fe8b219f642c7f8bc673215f28eb1d9dec51 # v0.10.0
         with:
           bazelisk-cache: true
-          disk-cache: ${{ github.workflow }}
+          disk-cache: ${{ github.workflow }}-${{ runner.os }}
           repository-cache: true
       - name: Build & Test
         run: bazel test //...

.gitignore

@@ -29,3 +29,4 @@ benchmarks/competitors/servo-url/target
 
 # bazel output
 bazel-*
+.clwb

BUILD.bazel

@@ -1,3 +1,13 @@
+# Platform definition for using clang-cl on Windows
+platform(
+    name = "x64_windows-clang-cl",
+    constraint_values = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:windows",
+        "@bazel_tools//tools/cpp:clang-cl",
+    ],
+)
+
 cc_library(
     name = "ada",
     srcs = [