Support netrc for Zig SDK download

toolchain/defs.bzl

@@ -1,5 +1,6 @@
 load("@bazel_skylib//lib:shell.bzl", "shell")
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+load("@bazel_tools//tools/build_defs/repo:utils.bzl", "read_netrc", "use_netrc")
 load(":zig_toolchain.bzl", "zig_cc_toolchain_config")
 
 DEFAULT_TOOL_PATHS = {
@@ -240,10 +241,10 @@ def _zig_repository_impl(repository_ctx):
         "host_platform": host_platform,
     }
 
-    url_formats = repository_ctx.attr.url_formats
+    urls = [uf.format(**format_vars) for uf in repository_ctx.attr.url_formats]
-
     repository_ctx.download_and_extract(
-        url = [uf.format(**format_vars) for uf in url_formats],
+        auth = use_netrc(_read_user_netrc(repository_ctx), urls, {}),
+        url = urls,
         stripPrefix = "zig-{host_platform}-{version}/".format(**format_vars),
         sha256 = zig_sha256,
     )
@@ -398,3 +399,25 @@ def zig_build_macro(absolute_path, zig_include_root):
                     name = "{os}_{gocpu}_platform".format(os = os, gocpu = gocpu),
                     constraint_values = constraint_values,
                 )
+
+# Copied from https://github.com/bazelbuild/bazel/blob/master/tools/build_defs/repo/utils.bzl
+# TODO: Upgrade to Bazel 5.1 and import this instead.
+def _read_user_netrc(ctx):
+    """Read user's default netrc file.
+    Args:
+      ctx: The repository context of the repository rule calling this utility function.
+    Returns:
+      dict mapping a machine names to a dict with the information provided about them.
+    """
+    if ctx.os.name.startswith("windows"):
+        home_dir = ctx.os.environ.get("USERPROFILE", "")
+    else:
+        home_dir = ctx.os.environ.get("HOME", "")
+
+    if not home_dir:
+        return {}
+
+    netrcfile = "{}/.netrc".format(home_dir)
+    if not ctx.path(netrcfile).exists:
+        return {}
+    return read_netrc(ctx, netrcfile)