fix: Make local runtime repo work on Windows

.gitignore

@@ -32,11 +32,11 @@
 *~
 
 # Bazel directories
-/bazel-*
-/bazel-bin
-/bazel-genfiles
-/bazel-out
-/bazel-testlogs
+bazel-*
+bazel-bin
+bazel-genfiles
+bazel-out
+bazel-testlogs
 user.bazelrc
 
 # vim swap files
@@ -51,4 +51,4 @@ user.bazelrc
 
 # MODULE.bazel.lock is ignored for now as per recommendation from upstream.
 # See https://github.com/bazelbuild/bazel/issues/20369
-MODULE.bazel.lock
+MODULE.bazel.lock

CHANGELOG.md

@@ -78,6 +78,7 @@ END_UNRELEASED_TEMPLATE
   multiple times.
 * (tools/wheelmaker.py) Extras are now preserved in Requires-Dist metadata when using requires_file
   to specify the requirements.
+* (toolchains) Local toolchains now supports Windows.
 
 {#v0-0-0-added}
 ### Added

python/private/BUILD.bazel

@@ -212,6 +212,7 @@ bzl_library(
     deps = [
         ":enum_bzl",
         ":repo_utils.bzl",
+        "@bazel_skylib//lib:paths",
     ],
 )
 

python/private/get_local_runtime_info.py

@@ -36,6 +36,9 @@
     # https://stackoverflow.com/questions/47423246/get-pythons-lib-path
     # For now, it seems LIBDIR has what is needed, so just use that.
     "LIBDIR",
+    # LIBDEST is the directory for platform-specific files; it's usually
+    # a subdirectory of LIBDIR. We use it in case LIBDIR isn't set.
+    "LIBDEST",
     # The versioned libpythonX.Y.so.N file. Usually?
     # It might be a static archive (.a) file instead.
     "INSTSONAME",
@@ -45,6 +48,9 @@
     # The platform-specific filename suffix for library files.
     # Includes the dot, e.g. `.so`
     "SHLIB_SUFFIX",
+    # A flag for whether this is a free threaded implementation.
+    # Set to t when free threading is enabled, '' or None otherwise.
+    "abi_thread",
 ]
 data.update(zip(config_vars, sysconfig.get_config_vars(*config_vars)))
 print(json.dumps(data))

python/private/local_runtime_repo.bzl

@@ -14,6 +14,7 @@
 
 """Create a repository for a locally installed Python runtime."""
 
+load("@bazel_skylib//lib:paths.bzl", "paths")
 load(":enum.bzl", "enum")
 load(":repo_utils.bzl", "REPO_DEBUG_ENV_VAR", "repo_utils")
 
@@ -112,13 +113,27 @@ def _local_runtime_repo_impl(rctx):
         info["INSTSONAME"],
     ]
 
+    if repo_utils.get_platforms_os_name(rctx) == "windows":
+        # Fall back to assuming no threading when no information is available
+        if info.get("abi_thread") == None:
+            info["abi_thread"] = ""
+
+        # Windows requires these library definitions to be linked in with the headers
+        shared_lib_names.append("python{major}{minor}{abi_thread}.lib".format(**info))
+        shared_lib_names.append("python{major}{abi_thread}.lib".format(**info))
+
+        interpreter_path = interpreter_path.replace("\\", "/")
+
     # In some cases, the value may be empty. Not clear why.
     shared_lib_names = [v for v in shared_lib_names if v]
 
     # In some cases, the same value is returned for multiple keys. Not clear why.
     shared_lib_names = {v: None for v in shared_lib_names}.keys()
     shared_lib_dir = info["LIBDIR"]
 
+    if shared_lib_dir == None:
+        shared_lib_dir = paths.dirname(info["LIBDEST"]) + "/libs"
+
     # The specific files are symlinked instead of the whole directory
     # because it can point to a directory that has more than just
     # the Python runtime shared libraries, e.g. /usr/lib, or a Python

python/private/local_runtime_repo_setup.bzl

@@ -15,6 +15,7 @@
 """Setup code called by the code generated by `local_runtime_repo`."""
 
 load("@bazel_skylib//lib:selects.bzl", "selects")
+load("@rules_cc//cc:cc_import.bzl", "cc_import")
 load("@rules_cc//cc:cc_library.bzl", "cc_library")
 load("@rules_python//python:py_runtime.bzl", "py_runtime")
 load("@rules_python//python:py_runtime_pair.bzl", "py_runtime_pair")
@@ -58,6 +59,20 @@ def define_local_runtime_toolchain_impl(
     major_minor = "{}.{}".format(major, minor)
     major_minor_micro = "{}.{}".format(major_minor, micro)
 
+    version_dict = {"major": major, "minor": minor}
+
+    cc_import(
+        name = "interface",
+        interface_library = "lib/python{major}{minor}.lib".format(**version_dict),
+        system_provided = True,
+    )
+
+    cc_import(
+        name = "abi3_interface",
+        interface_library = "lib/python3.lib",
+        system_provided = True,
+    )
+
     cc_library(
         name = "_python_headers",
         # NOTE: Keep in sync with watch_tree() called in local_runtime_repo
@@ -67,6 +82,10 @@ def define_local_runtime_toolchain_impl(
             allow_empty = True,
         ),
         includes = ["include"],
+        deps = select({
+            "@platforms//os:windows": [":interface", ":abi3_interface"],
+            "//conditions:default": None,
+        }),
     )
 
     cc_library(