Fix clippy_repository

Author: dzbarsky

rs/experimental/toolchains/module_extension.bzl

@@ -205,6 +205,7 @@ def _toolchains_impl(mctx):
                     version = base_version,
                     iso_date = iso_date,
                     sha256 = _sha_for("clippy", base_version, iso_date, exec_triple),
+                    rustc_repo_build_file = "@rustc_{}_{}//:BUILD.bazel".format(triple_suffix, version_key),
                 )
 
         if version in versions:

rs/private/clippy_repository.bzl

@@ -7,9 +7,14 @@ def _clippy_repository_impl(rctx):
     download_and_extract(rctx, "clippy", "clippy-preview", exec_triple)
     rctx.file("BUILD.bazel", BUILD_for_clippy(exec_triple))
 
+    rustc_repo_root = rctx.path(rctx.attr.rustc_repo_build_file).dirname
+    rctx.symlink(rustc_repo_root.get_child("lib"), "lib")
+
     return rctx.repo_metadata(reproducible = True)
 
 clippy_repository = repository_rule(
     implementation = _clippy_repository_impl,
-    attrs = RUST_REPOSITORY_COMMON_ATTR,
+    attrs = {
+        "rustc_repo_build_file": attr.label(allow_single_file = True, mandatory = True),
+    } | RUST_REPOSITORY_COMMON_ATTR,
 )