Invalid use of @overload v2

tools/pylint-extensions/azure-pylint-guidelines-checker/README.md

@@ -95,4 +95,5 @@ In the case of a false positive, use the disable command to remove the pylint er
 | no-typing-import-in-type-check                     | Do not import typing under TYPE_CHECKING.                                                                                                                            | pylint:disable=no-typing-import-in-type-check                       | No Link.                                                                                                |
 | do-not-log-raised-errors                           | Do not log errors at `error` or `warning` level when error is raised in an exception block.                                                                          | pylint:disable=do-not-log-raised-errors                             | No Link.                                                                                                |
 | do-not-use-legacy-typing                           | Do not use legacy (<Python 3.8) type hinting comments                                                                                                             | pylint:disable=do-not-use-legacy-typing                             | No Link.
-| do-not-import-asyncio                              | Do not import asyncio directly.                                                                                                                                      | pylint:disable=do-not-import-asyncio                                | No Link.                                                                                                |
+| do-not-import-asyncio                              | Do not import asyncio directly.                                                                                                                                      | pylint:disable=do-not-import-asyncio                                | No Link.                                                                                                |
+| invalid-use-of-overload                            | Do not mix async and synchronous overloads                                                                                                                           | pylint:disable=invalid-use-of-overload                              | No Link.                                                                                                |

tools/pylint-extensions/azure-pylint-guidelines-checker/pylint_guidelines_checker.py

@@ -2865,6 +2865,65 @@ def visit_import(self, node):
 
 
 # [Pylint] custom linter check for invalid use of @overload #3229
+
+
+class InvalidUseOfOverload(BaseChecker):
+    """Rule to check that use of the @overload decorator matches the async/sync nature of the underlying function"""
+
+    name = "invalid-use-of-overload"
+    priority = -1
+    msgs = {
+        "C4765": (
+            "Do not mix async and synchronous overloads",
+            "invalid-use-of-overload",
+            "Functions and their overloads must be either all async or all synchronous.",
+        ),
+    }
+
+    def visit_classdef(self, node):
+        """Check that use of the @overload decorator matches the async/sync nature of the underlying function"""
+
+        # Obtain a list of all functions and function names
+        functions = []
+        node.body
+        for item in node.body:
+            if hasattr(item, 'name'):
+                functions.append(item)
+
+        # Dictionary of lists of all functions by name
+        overloadedfunctions = {}
+        for item in functions:
+            if item.name in overloadedfunctions:
+                overloadedfunctions[item.name].append(item)
+            else:
+                overloadedfunctions[item.name] = [item]
+
+
+        # Loop through the overloaded functions and check they are the same type
+        for funct in overloadedfunctions.values():
+            if len(funct) > 1:  # only need to check if there is more than 1 function with the same name
+                function_is_async = None
+
+                for item in funct:
+                    if function_is_async is None:
+                        function_is_async = self.is_function_async(item)
+
+                    else:
+                        if function_is_async != self.is_function_async(item):
+                            self.add_message(
+                                msgid=f"invalid-use-of-overload",
+                                node=item,
+                                confidence=None,
+                            )
+
+
+    def is_function_async(self, node):
+        try:
+            str(node.__class__).index("Async")
+            return True
+        except:
+            return False
+
 # [Pylint] Custom Linter check for Exception Logging #3227
 # [Pylint] Address Commented out Pylint Custom Plugin Checkers #3228
 # [Pylint] Add a check for connection_verify hardcoded settings #35355
@@ -2907,8 +2966,7 @@ def register(linter):
     linter.register_checker(NoImportTypingFromTypeCheck(linter))
     linter.register_checker(DoNotUseLegacyTyping(linter))
     linter.register_checker(DoNotLogErrorsEndUpRaising(linter))
-
-    # [Pylint] custom linter check for invalid use of @overload #3229
+    linter.register_checker(InvalidUseOfOverload(linter))
     # [Pylint] Custom Linter check for Exception Logging #3227
     # [Pylint] Address Commented out Pylint Custom Plugin Checkers #3228
     # [Pylint] Add a check for connection_verify hardcoded settings #35355

tools/pylint-extensions/azure-pylint-guidelines-checker/tests/test_files/invalid_use_of_overload_acceptable.py

@@ -0,0 +1,31 @@
+# Test file for InvalidUseOfOverload checker
+
+from typing import overload, Union
+
+class testingOverload:
+    @overload
+    async def double(a: str):
+        ...
+
+    @overload
+    async def double(a: int):
+        ...
+
+    async def double(a: Union[str, int]) -> int:
+        if isinstance(a, str):
+            return len(a)*2
+        return a * 2
+
+
+    @overload
+    def single(a: str):
+        ...
+
+    @overload
+    def single(a: int):
+        ...
+
+    def single(a: Union[str, int]) -> int:
+        if isinstance(a, str):
+            return len(a)
+        return a

tools/pylint-extensions/azure-pylint-guidelines-checker/tests/test_files/invalid_use_of_overload_violation.py

@@ -0,0 +1,31 @@
+# Test file for InvalidUseOfOverload checker - testing what mypy doesn't pick up
+
+from typing import overload, Union
+
+class testingOverload:
+    @overload
+    def double(a: str):
+        ...
+
+    @overload
+    def double(a: int):
+        ...
+
+    async def double(a: Union[str, int]):
+        if isinstance(a, str):
+            return len(a)*2
+        return a * 2
+
+
+    @overload
+    async def doubleAgain(a: str) -> int:
+        ...
+
+    @overload
+    def doubleAgain(a: int) -> int:
+        ...
+
+    async def doubleAgain(a: Union[str, int]) -> int:
+        if isinstance(a, str):
+            return len(a)*2
+        return a * 2

tools/pylint-extensions/azure-pylint-guidelines-checker/tests/test_pylint_custom_plugins.py

@@ -3597,7 +3597,53 @@ def test_extra_nested_branches_exception_logged(self, setup):
         ):
             self.checker.visit_try(try_node)
 
-# [Pylint] custom linter check for invalid use of @overload #3229
+class TestInvalidUseOfOverload(pylint.testutils.CheckerTestCase):
+    """Test that use of the @overload decorator matches the async/sync nature of the underlying function"""
+
+    CHECKER_CLASS = checker.InvalidUseOfOverload
+
+    def test_valid_use_overload(self):
+        file = open(
+            os.path.join(
+                TEST_FOLDER, "test_files", "invalid_use_of_overload_acceptable.py"
+            )
+        )
+        node = astroid.parse(file.read())
+        file.close()
+        with self.assertNoMessages():
+            self.checker.visit_classdef(node.body[1])
+
+
+    def test_invalid_use_overload(self):
+        file = open(
+            os.path.join(
+                TEST_FOLDER, "test_files", "invalid_use_of_overload_violation.py"
+            )
+        )
+        node = astroid.extract_node(file.read())
+        file.close()
+
+        with self.assertAddsMessages(
+            pylint.testutils.MessageTest(
+                msg_id="invalid-use-of-overload",
+                line=14,
+                node=node.body[2],
+                col_offset=4,
+                end_line=14,
+                end_col_offset=20,
+            ),
+            pylint.testutils.MessageTest(
+                msg_id="invalid-use-of-overload",
+                line=25,
+                node=node.body[4],
+                col_offset=4,
+                end_line=25,
+                end_col_offset=19,
+            ),
+        ):
+            self.checker.visit_classdef(node)
+
+
 # [Pylint] Custom Linter check for Exception Logging #3227
 # [Pylint] Address Commented out Pylint Custom Plugin Checkers #3228
 # [Pylint] Add a check for connection_verify hardcoded settings #35355