build_meta: Allow dist-info and egg-info to coexist

PEP 517 does not care if other directories/files are left behind in the
`metadata_directory`, as long as a `.dist_info` directory is produced at
the root. We can leave the `.egg-info` directory behind, so this way
we don't have to run it again when listing files from `build_py`.

1 files changed, 22 insertions, 0 deletions

diff --git a/setuptools/_path.py b/setuptools/_path.py
index ede9cb00..3767523b 100644
--- a/setuptools/_path.py
+++ b/setuptools/_path.py
@@ -1,7 +1,29 @@
 import os
+from typing import Union
+
+_Path = Union[str, os.PathLike]
 
 
 def ensure_directory(path):
     """Ensure that the parent directory of `path` exists"""
     dirname = os.path.dirname(path)
     os.makedirs(dirname, exist_ok=True)
+
+
+def same_path(p1: _Path, p2: _Path) -> bool:
+    """Differs from os.path.samefile because it does not require paths to exist.
+    Purely string based (no comparison between i-nodes).
+    >>> same_path("a/b", "./a/b")
+    True
+    >>> same_path("a/b", "a/./b")
+    True
+    >>> same_path("a/b", "././a/b")
+    True
+    >>> same_path("a/b", "./a/b/c/..")
+    True
+    >>> same_path("a/b", "../a/b/c")
+    False
+    >>> same_path("a", "a/b")
+    False
+    """
+    return os.path.normpath(p1) == os.path.normpath(p2)