Refactor ConfigDiscovery._root_dir as a property

1 files changed, 5 insertions, 3 deletions

diff --git a/setuptools/discovery.py b/setuptools/discovery.py
index 837cea9e..b9aedfb0 100644
--- a/setuptools/discovery.py
+++ b/setuptools/discovery.py
@@ -270,12 +270,16 @@ class ConfigDiscovery:
         self.dist = distribution
         self._called = False
         self._disabled = False
-        self._root_dir: _Path  # delay so `src_root` can be set in dist
 
     def _disable(self):
         """Internal API to disable automatic discovery"""
         self._disabled = True
 
+    @property
+    def _root_dir(self) -> _Path:
+        # The best is to wait until `src_root` is set in dist, before using _root_dir.
+        return self.dist.src_root or os.curdir
+
     def __call__(self, force=False, name=True):
         """Automatically discover missing configuration fields
         and modifies the given ``distribution`` object in-place.
@@ -291,8 +295,6 @@ class ConfigDiscovery:
             # Avoid overhead of multiple calls
             return
 
-        self._root_dir = self.dist.src_root or os.curdir
-
         self._analyse_package_layout()
         if name:
             self.analyse_name()  # depends on ``packages`` and ``py_modules``