Do not lint ignored file on stdin (#7220)

Previously pylint would lint a file passed on stdin even if the user
meant to ignore the file. This commit fixes that issue.

Co-authored-by: Daniël van Noord <[email protected]>

doc/whatsnew/fragments/4354.bugfix

@@ -0,0 +1,3 @@
+Fix ignored files being linted when passed on stdin.
+
+Closes #4354

pylint/lint/pylinter.py

@@ -660,9 +660,7 @@ def check(self, files_or_modules: Sequence[str] | str) -> None:
         # 3) Get all FileItems
         with fix_import_path(files_or_modules):
             if self.config.from_stdin:
-                fileitems = iter(
-                    (self._get_file_descr_from_stdin(files_or_modules[0]),)
-                )
+                fileitems = self._get_file_descr_from_stdin(files_or_modules[0])
                 data: str | None = _read_stdin()
             else:
                 fileitems = self._iterate_file_descrs(files_or_modules)
@@ -817,14 +815,21 @@ def _check_file(
         for msgid, line, args in spurious_messages:
             self.add_message(msgid, line, None, args)
 
-    @staticmethod
-    def _get_file_descr_from_stdin(filepath: str) -> FileItem:
+    def _get_file_descr_from_stdin(self, filepath: str) -> Iterator[FileItem]:
         """Return file description (tuple of module name, file path, base name) from
         given file path.
 
         This method is used for creating suitable file description for _check_files when the
         source is standard input.
         """
+        if _is_ignored_file(
+            filepath,
+            self.config.ignore,
+            self.config.ignore_patterns,
+            self.config.ignore_paths,
+        ):
+            return
+
         try:
             # Note that this function does not really perform an
             # __import__ but may raise an ImportError exception, which
@@ -833,7 +838,7 @@ def _get_file_descr_from_stdin(filepath: str) -> FileItem:
         except ImportError:
             modname = os.path.splitext(os.path.basename(filepath))[0]
 
-        return FileItem(modname, filepath, filepath)
+        yield FileItem(modname, filepath, filepath)
 
     def _iterate_file_descrs(
         self, files_or_modules: Sequence[str]

tests/test_self.py

@@ -1128,6 +1128,20 @@ def test_ignore_pattern_recursive(self, ignore_pattern_value: str) -> None:
             code=0,
         )
 
+    def test_ignore_pattern_from_stdin(self) -> None:
+        """Test if linter ignores standard input if the filename matches the ignore pattern."""
+        with mock.patch("pylint.lint.pylinter._read_stdin", return_value="import os\n"):
+            self._runtest(
+                [
+                    "--from-stdin",
+                    "mymodule.py",
+                    "--disable=all",
+                    "--enable=unused-import",
+                    "--ignore-patterns=mymodule.py",
+                ],
+                code=0,
+            )
+
     @pytest.mark.parametrize("ignore_path_value", [".*ignored.*", ".*failing.*"])
     def test_ignore_path_recursive(self, ignore_path_value: str) -> None:
         """Tests recursive run of linter ignoring directory using --ignore-path parameter.