Fix recognition of config files named setup.cfg (#3630) (#6577)

Co-authored-by: Daniël van Noord <13665637+DanielNoord@users.noreply.github.com>

doc/whatsnew/2/2.14/full.rst

@@ -23,6 +23,12 @@ Release date: TBA
 
   Closes #6965
 
+* Fixed an issue with the recognition of ``setup.cfg`` files.
+  Only ``.cfg`` files that are exactly named ``setup.cfg`` require section names that
+  start with ``pylint.``.
+
+  Closes #3630
+
 * Don't report ``import-private-name`` for relative imports.
 
   Closes #7078

pylint/config/config_file_parser.py

@@ -42,7 +42,7 @@ def _parse_ini_file(self, file_path: Path) -> tuple[dict[str, str], list[str]]:
         config_content: dict[str, str] = {}
         options: list[str] = []
         for section in parser.sections():
-            if self._ini_file_with_sections(str(file_path)) and not section.startswith(
+            if self._ini_file_with_sections(file_path) and not section.startswith(
                 "pylint"
             ):
                 if section.lower() == "master":
@@ -61,11 +61,11 @@ def _parse_ini_file(self, file_path: Path) -> tuple[dict[str, str], list[str]]:
         return config_content, options
 
     @staticmethod
-    def _ini_file_with_sections(file_path: str) -> bool:
+    def _ini_file_with_sections(file_path: Path) -> bool:
         """Return whether the file uses sections."""
-        if "setup.cfg" in file_path:
+        if "setup.cfg" in file_path.parts:
             return True
-        if "tox.ini" in file_path:
+        if "tox.ini" in file_path.parts:
             return True
         return False
 

tests/config/functional/setup_cfg/issue_3630/not_setup.2.out

@@ -0,0 +1,3 @@
+I should just print
+************* Module Command line or configuration file
+Command line or configuration file:1:0: E0013: Plugin 'pylint_flask' is impossible to load, is it installed ? ('No module named 'pylint_flask'') (bad-plugin-value)

tests/config/functional/setup_cfg/issue_3630/not_setup.cfg

@@ -0,0 +1,12 @@
+# We load all sections as this is not a file that requires correct section headers
+[tool.pylint.MASTER]
+init-hook='print("I should just print")'
+
+# We still load from pylint.
+[pylint.MASTER]
+load-plugins=pylint_flask
+
+# We even load from section without pylint in their name
+[FORMAT]
+max-line-length=220
+max-module-lines=2001

tests/config/functional/setup_cfg/issue_3630/not_setup.result.json

@@ -0,0 +1,5 @@
+{
+  "load_plugins": ["pylint_flask"],
+  "max_line_length": 220,
+  "max_module_lines": 2001
+}

tests/config/functional/setup_cfg/issue_3630/setup.2.out

@@ -0,0 +1,2 @@
+************* Module Command line or configuration file
+Command line or configuration file:1:0: E0013: Plugin 'pylint_flask' is impossible to load, is it installed ? ('No module named 'pylint_flask'') (bad-plugin-value)

tests/config/functional/setup_cfg/issue_3630/setup.cfg

@@ -0,0 +1,12 @@
+# Don't load from tool.pylint, we only support pylint.
+[tool.pylint.MASTER]
+init-hook='print("I should NOT print in setup.cfg we only parse 'pylint.'")'
+
+# We do load from pylint.
+[pylint.MASTER]
+load-plugins=pylint_flask
+
+# We don't load options from random sections
+[FORMAT]
+max-line-length=220
+max-module-lines=2001

tests/config/functional/setup_cfg/issue_3630/setup.result.json

@@ -0,0 +1,3 @@
+{
+  "load_plugins": ["pylint_flask"]
+}