From 49358d4e91e4cee6d38d08baab574a6ce971ca09 Mon Sep 17 00:00:00 2001
From: Matej Spiller Muys <matej.spiller-muys@bitstamp.net>
Date: Mon, 13 Nov 2023 11:38:53 +0100
Subject: [PATCH] Support for resolving external toml files

---
 doc/user_guide/usage/run.rst                  |  4 +++
 doc/whatsnew/fragments/9228.feature           |  3 ++
 pylint/config/find_default_config_files.py    |  7 +++-
 .../config/test_find_default_config_files.py  | 35 +++++++++++++++++++
 4 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 doc/whatsnew/fragments/9228.feature

diff --git a/doc/user_guide/usage/run.rst b/doc/user_guide/usage/run.rst
index 081517a39b..3136181254 100644
--- a/doc/user_guide/usage/run.rst
+++ b/doc/user_guide/usage/run.rst
@@ -95,7 +95,11 @@ command line using the ``--rcfile`` option.  Otherwise, Pylint searches for a
 configuration file in the following order and uses the first one it finds:
 
 #. ``pylintrc`` in the current working directory
+#. ``pylintrc.toml`` in the current working directory,
+   providing it has at least one ``tool.pylint.`` section.
 #. ``.pylintrc`` in the current working directory
+#. ``.pylintrc.toml`` in the current working directory,
+   providing it has at least one ``tool.pylint.`` section.
 #. ``pyproject.toml`` in the current working directory,
    providing it has at least one ``tool.pylint.`` section.
    The ``pyproject.toml`` must prepend section names with ``tool.pylint.``,
diff --git a/doc/whatsnew/fragments/9228.feature b/doc/whatsnew/fragments/9228.feature
new file mode 100644
index 0000000000..e7b984014c
--- /dev/null
+++ b/doc/whatsnew/fragments/9228.feature
@@ -0,0 +1,3 @@
+Support for resolving external toml files named pylintrc.toml and .pylintrc.toml.
+
+Closes #9228
diff --git a/pylint/config/find_default_config_files.py b/pylint/config/find_default_config_files.py
index 3b03f6357b..346393cf9a 100644
--- a/pylint/config/find_default_config_files.py
+++ b/pylint/config/find_default_config_files.py
@@ -15,7 +15,12 @@
 else:
     import tomli as tomllib
 
-RC_NAMES = (Path("pylintrc"), Path(".pylintrc"))
+RC_NAMES = (
+    Path("pylintrc"),
+    Path("pylintrc.toml"),
+    Path(".pylintrc"),
+    Path(".pylintrc.toml"),
+)
 PYPROJECT_NAME = Path("pyproject.toml")
 CONFIG_NAMES = (*RC_NAMES, PYPROJECT_NAME, Path("setup.cfg"))
 
diff --git a/tests/config/test_find_default_config_files.py b/tests/config/test_find_default_config_files.py
index 0b513a3d5f..6a8095c5d7 100644
--- a/tests/config/test_find_default_config_files.py
+++ b/tests/config/test_find_default_config_files.py
@@ -129,6 +129,41 @@ def test_pylintrc_parentdir() -> None:
             assert next(config.find_default_config_files()) == expected
 
 
+@pytest.mark.usefixtures("pop_pylintrc")
+def test_pylintrc_toml_parentdir() -> None:
+    """Test that the first pylintrc.toml we find is the first parent directory."""
+    # pylint: disable=duplicate-code
+    with tempdir() as chroot:
+        chroot_path = Path(chroot)
+        files = [
+            "a/pylintrc.toml",
+            "a/b/__init__.py",
+            "a/b/pylintrc.toml",
+            "a/b/c/__init__.py",
+            "a/b/c/d/__init__.py",
+            "a/b/c/d/e/.pylintrc.toml",
+        ]
+        testutils.create_files(files)
+        for config_file in files:
+            if config_file.endswith("pylintrc.toml"):
+                with open(config_file, "w", encoding="utf-8") as fd:
+                    fd.write('[tool.pylint."messages control"]\n')
+
+        with fake_home():
+            assert not list(config.find_default_config_files())
+
+        results = {
+            "a": chroot_path / "a" / "pylintrc.toml",
+            "a/b": chroot_path / "a" / "b" / "pylintrc.toml",
+            "a/b/c": chroot_path / "a" / "b" / "pylintrc.toml",
+            "a/b/c/d": chroot_path / "a" / "b" / "pylintrc.toml",
+            "a/b/c/d/e": chroot_path / "a" / "b" / "c" / "d" / "e" / ".pylintrc.toml",
+        }
+        for basedir, expected in results.items():
+            os.chdir(chroot_path / basedir)
+            assert next(config.find_default_config_files()) == expected
+
+
 @pytest.mark.usefixtures("pop_pylintrc")
 def test_pyproject_toml_parentdir() -> None:
     """Test the search of pyproject.toml file in parent directories"""