From 71271d58e7c094a2b1c27e2c94ada788113b27ab Mon Sep 17 00:00:00 2001
From: hauntsaninja <>
Date: Fri, 23 Oct 2020 15:55:12 -0700
Subject: [PATCH] add back in caching

---
 mypy/find_sources.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mypy/find_sources.py b/mypy/find_sources.py
index 8db929eb95ba..20605f727fe5 100644
--- a/mypy/find_sources.py
+++ b/mypy/find_sources.py
@@ -1,5 +1,6 @@
 """Routines for finding the sources that mypy will check"""
 
+import functools
 import os.path
 
 from typing import List, Sequence, Set, Tuple, Optional, Dict
@@ -140,6 +141,8 @@ def crawl_up(self, path: str) -> Tuple[str, str]:
 
         return module, base_dir
 
+    # Add a cache in case many files are passed to mypy
+    @functools.lru_cache()
     def crawl_up_dir(self, dir: str) -> Tuple[str, str]:
         """Given a directory name, return the corresponding module name and base directory."""
         parent_dir, base = os.path.split(dir)