GH-70303: Emit FutureWarning when pathlib glob pattern ends with `**` (GH-105413)

In a future Python release, patterns with this ending will match both files
and directories. Users may add a trailing slash to remove the warning.

2 files changed, 21 insertions, 3 deletions

diff --git a/Lib/pathlib.py b/Lib/pathlib.py
index c83cf3d..758f70f 100644
--- a/Lib/pathlib.py
+++ b/Lib/pathlib.py
@@ -1069,6 +1069,11 @@ class Path(PurePath):
             pattern_parts.append('')
         if pattern_parts[-1] == '**':
             # GH-70303: '**' only matches directories. Add trailing slash.
+            warnings.warn(
+                "Pattern ending '**' will match files and directories in a "
+                "future Python release. Add a trailing slash to match only "
+                "directories and remove this warning.",
+                FutureWarning, 3)
             pattern_parts.append('')
 
         if case_sensitive is None:
diff --git a/Lib/test/test_pathlib.py b/Lib/test/test_pathlib.py
index 5789a93..74deec8 100644
--- a/Lib/test/test_pathlib.py
+++ b/Lib/test/test_pathlib.py
@@ -1903,11 +1903,11 @@ class PathTest(unittest.TestCase):
                               "dirC/dirD", "dirC/dirD/fileD"])
         _check(p.rglob("file*"), ["dirC/fileC", "dirC/dirD/fileD"])
         _check(p.rglob("**/file*"), ["dirC/fileC", "dirC/dirD/fileD"])
-        _check(p.rglob("dir*/**"), ["dirC/dirD"])
+        _check(p.rglob("dir*/**/"), ["dirC/dirD"])
         _check(p.rglob("*/*"), ["dirC/dirD/fileD"])
         _check(p.rglob("*/"), ["dirC/dirD"])
         _check(p.rglob(""), ["dirC", "dirC/dirD"])
-        _check(p.rglob("**"), ["dirC", "dirC/dirD"])
+        _check(p.rglob("**/"), ["dirC", "dirC/dirD"])
         # gh-91616, a re module regression
         _check(p.rglob("*.txt"), ["dirC/novel.txt"])
         _check(p.rglob("*.*"), ["dirC/novel.txt"])
@@ -2057,7 +2057,20 @@ class PathTest(unittest.TestCase):
         path.mkdir(parents=True)
 
         with set_recursion_limit(recursion_limit):
-            list(base.glob('**'))
+            list(base.glob('**/'))
+
+    def test_glob_recursive_no_trailing_slash(self):
+        P = self.cls
+        p = P(BASE)
+        with self.assertWarns(FutureWarning):
+            p.glob('**')
+        with self.assertWarns(FutureWarning):
+            p.glob('*/**')
+        with self.assertWarns(FutureWarning):
+            p.rglob('**')
+        with self.assertWarns(FutureWarning):
+            p.rglob('*/**')
+
 
     def test_readlink(self):
         if not self.can_symlink: