added support for Windows targets

README.md

@@ -152,6 +152,8 @@ register_toolchains(
     "@zig_sdk//toolchain:linux_arm64_gnu.2.28",
     "@zig_sdk//toolchain:darwin_amd64",
     "@zig_sdk//toolchain:darwin_arm64",
+    "@zig_sdk//toolchain:windows_amd64",
+    "@zig_sdk//toolchain:windows_arm64",
 )
 ```
 
@@ -318,6 +320,18 @@ is currently not implemented.
 target macos.10 (Catalina), macos.11 (Big Sur) or macos.12 (Monterey). It
 currently targets the lowest version, without ability to change it.
 
+## Windows: output file extensions
+
+Bazel won't use common Windows file extensions for built output binaries.
+Instead, it will generate binaries with common Unix extensions that you might
+have to manually rename before deploying them to an actual Windows system:
+
+| Binary type    | Bazel extension | Windows extension |
+|----------------|-----------------|-------------------|
+| Static library | .a              | .lib              |
+| Shared library | .so             | .dll              |
+| Executable     | (no extension)  | .exe              |
+
 # Known Issues In Upstream
 
 This section lists issues that I've stumbled into when using `zig cc`, and is

toolchain/platform/defs.bzl

@@ -1,11 +1,16 @@
 load("@bazel-zig-cc//toolchain/private:defs.bzl", "LIBCS")
 
 _CPUS = (("x86_64", "amd64"), ("aarch64", "arm64"))
+_OS = {
+    "linux": ["linux"],
+    "macos": ["macos", "darwin"],
+    "windows": ["windows"],
+}
 
 def declare_platforms():
     # create @zig_sdk//{os}_{arch}_platform entries with zig and go conventions
     for zigcpu, gocpu in _CPUS:
-        for bzlos, oss in {"linux": ["linux"], "macos": ["macos", "darwin"]}.items():
+        for bzlos, oss in _OS.items():
             for os in oss:
                 declare_platform(gocpu, zigcpu, bzlos, os)
 

toolchain/private/defs.bzl

@@ -40,6 +40,7 @@ def target_structs():
     ret = []
     for zigcpu, gocpu in (("x86_64", "amd64"), ("aarch64", "arm64")):
         ret.append(_target_darwin(gocpu, zigcpu))
+        ret.append(_target_windows(gocpu, zigcpu))
         ret.append(_target_linux_musl(gocpu, zigcpu))
         for glibc in _GLIBCS:
             ret.append(_target_linux_gnu(gocpu, zigcpu, glibc))
@@ -70,6 +71,24 @@ def _target_darwin(gocpu, zigcpu):
         tool_paths = {"ld": "ld64.lld"},
     )
 
+def _target_windows(gocpu, zigcpu):
+    return struct(
+        gotarget = "windows_{}".format(gocpu),
+        zigtarget = "{}-windows-gnu".format(zigcpu),
+        includes = [
+            "libunwind/include",
+            "libc/include/any-windows-any",
+        ],
+        linkopts = [],
+        copts = [],
+        bazel_target_cpu = "x64_windows",
+        constraint_values = [
+            "@platforms//os:windows",
+            "@platforms//cpu:{}".format(zigcpu),
+        ],
+        tool_paths = {"ld": "ld64.lld"},
+    )
+
 def _target_linux_gnu(gocpu, zigcpu, glibc_version):
     glibc_suffix = "gnu.{}".format(glibc_version)