Fix saving of persistent data files on different drives (#6526)

4 files changed, 75 insertions, 7 deletions

diff --git a/ChangeLog b/ChangeLog
index 405d85f4e..aec24186b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -293,6 +293,11 @@ Release date: TBA
 
   Closes #5502
 
+* Fix saving of persistent data files in environments where the user's cache
+  directory and the linted file are on a different drive.
+
+  Closes #6394
+
 ..
   Insert your changelog randomly, it will reduce merge conflicts
   (Ie. not necessarily at the end)
diff --git a/doc/whatsnew/2.14.rst b/doc/whatsnew/2.14.rst
index bf97f475d..d59c4792e 100644
--- a/doc/whatsnew/2.14.rst
+++ b/doc/whatsnew/2.14.rst
@@ -266,6 +266,11 @@ Other Changes
 
   Closes #5670
 
+* Fix saving of persistent data files in environments where the user's cache
+  directory and the linted file are on a different drive.
+
+  Closes #6394
+
 * The ``method-cache-max-size-none`` checker will now also check ``functools.cache``.
 
   Closes #5670
diff --git a/pylint/lint/caching.py b/pylint/lint/caching.py
index ec5a9f78a..573b97628 100644
--- a/pylint/lint/caching.py
+++ b/pylint/lint/caching.py
@@ -16,7 +16,12 @@ from pylint.utils import LinterStats
 def _get_pdata_path(
     base_name: Path, recurs: int, pylint_home: Path = Path(PYLINT_HOME)
 ) -> Path:
-    underscored_name = "_".join(str(p) for p in base_name.parts)
+    # We strip all characters that can't be used in a filename
+    # Also strip '/' and '\\' because we want to create a single file, not sub-directories
+    underscored_name = "_".join(
+        str(p.replace(":", "_").replace("/", "_").replace("\\", "_"))
+        for p in base_name.parts
+    )
     return pylint_home / f"{underscored_name}_{recurs}.stats"
 
 
diff --git a/tests/lint/test_caching.py b/tests/lint/test_caching.py
index 8d3f7afd4..fe6ccc234 100644
--- a/tests/lint/test_caching.py
+++ b/tests/lint/test_caching.py
@@ -5,6 +5,7 @@
 # Pytest fixtures work like this by design
 # pylint: disable=redefined-outer-name
 
+import sys
 from pathlib import Path
 
 import pytest
@@ -18,15 +19,67 @@ PYLINT_HOME_PATH = Path(PYLINT_HOME)
 
 
 @pytest.mark.parametrize(
-    "path,recur,expected",
+    "path,recur,pylint_home,expected",
     [
-        ["", 1, PYLINT_HOME_PATH / "_1.stats"],
-        ["", 2, PYLINT_HOME_PATH / "_2.stats"],
-        ["a/path", 42, PYLINT_HOME_PATH / "a_path_42.stats"],
+        ["", 1, PYLINT_HOME_PATH, PYLINT_HOME_PATH / "_1.stats"],
+        ["", 2, PYLINT_HOME_PATH, PYLINT_HOME_PATH / "_2.stats"],
+        ["a/path", 42, PYLINT_HOME_PATH, PYLINT_HOME_PATH / "a_path_42.stats"],
     ],
 )
-def test__get_pdata_path(path: str, recur: int, expected: Path) -> None:
-    assert _get_pdata_path(Path(path), recur) == expected
+def test__get_pdata_path(
+    path: str, recur: int, pylint_home: Path, expected: Path
+) -> None:
+    assert _get_pdata_path(Path(path), recur, pylint_home) == expected
+
+
+@pytest.mark.skipif(sys.platform == "win32", reason="Path type of *nix")
+@pytest.mark.parametrize(
+    "path,recur,pylint_home,expected",
+    [
+        [
+            "/workspace/MyDir/test.py",
+            1,
+            Path("/root/.cache/pylint"),
+            Path("/root/.cache/pylint") / "__workspace_MyDir_test.py_1.stats",
+        ],
+        [
+            "/workspace/MyDir/test.py",
+            1,
+            Path("//host/computer/.cache"),
+            Path("//host/computer/.cache") / "__workspace_MyDir_test.py_1.stats",
+        ],
+    ],
+)
+def test__get_pdata_path_nix(
+    path: str, recur: int, pylint_home: Path, expected: Path
+) -> None:
+    """test__get_pdata_path but specifically for *nix system paths."""
+    assert _get_pdata_path(Path(path), recur, pylint_home) == expected
+
+
+@pytest.mark.skipif(sys.platform != "win32", reason="Path type of windows")
+@pytest.mark.parametrize(
+    "path,recur,pylint_home,expected",
+    [
+        [
+            "D:\\MyDir\\test.py",
+            1,
+            Path("C:\\Users\\MyPylintHome"),
+            Path("C:\\Users\\MyPylintHome") / "D___MyDir_test.py_1.stats",
+        ],
+        [
+            "C:\\MyDir\\test.py",
+            1,
+            Path("C:\\Users\\MyPylintHome"),
+            Path("C:\\Users\\MyPylintHome") / "C___MyDir_test.py_1.stats",
+        ],
+    ],
+)
+def test__get_pdata_path_windows(
+    path: str, recur: int, pylint_home: Path, expected: Path
+) -> None:
+    """test__get_pdata_path but specifically for windows."""
+    assert _get_pdata_path(Path(path), recur, pylint_home) == expected
 
 
 @pytest.fixture