Fix false positive warning in check_function_inputs_match (#3837)

* fix false positive warning of check_function_inputs_match

* apply linter

* Update CHANGELOG and add comments in test

* Lint

---------

Co-authored-by: Freddy Boulton <alfonsoboulton@gmail.com>
Co-authored-by: Abubakar Abid <abubakar@huggingface.co>

CHANGELOG.md

@@ -184,7 +184,7 @@ No changes to highlight.
 ## Bug Fixes:
 
 - Fixes Chatbot issue where new lines were being created every time a message was sent back and forth by [@aliabid94](https://github.com/aliabid94) in [PR 3717](https://github.com/gradio-app/gradio/pull/3717).
-
+- Fixes false postive warning which is due to too strict type checking by [@yiyuezhuo](https://github.com/yiyuezhuo) in [PR 3837](https://github.com/gradio-app/gradio/pull/3837).
 
 ## Documentation Changes:
 

gradio/utils.py

@@ -837,6 +837,14 @@ def get_cancel_function(
     )
 
 
+def get_type_hints(fn):
+    if inspect.isfunction(fn) or inspect.ismethod(fn):
+        return typing.get_type_hints(fn)
+    elif callable(fn):
+        return typing.get_type_hints(fn.__call__)
+    return {}
+
+
 def check_function_inputs_match(fn: Callable, inputs: List, inputs_as_dict: bool):
     """
     Checks if the input component set matches the function
@@ -854,7 +862,7 @@ def check_function_inputs_match(fn: Callable, inputs: List, inputs_as_dict: bool
         return is_request or is_event_data
 
     signature = inspect.signature(fn)
-    parameter_types = typing.get_type_hints(fn) if inspect.isfunction(fn) else {}
+    parameter_types = get_type_hints(fn)
     min_args = 0
     max_args = 0
     infinity = -1

test/test_utils.py

@@ -14,6 +14,7 @@ from httpx import AsyncClient, Response
 from pydantic import BaseModel
 from typing_extensions import Literal
 
+from gradio import EventData
 from gradio.context import Context
 from gradio.test_data.blocks_configs import (
     XRAY_CONFIG,
@@ -25,11 +26,13 @@ from gradio.utils import (
     abspath,
     append_unique_suffix,
     assert_configs_are_equivalent_besides_ids,
+    check_function_inputs_match,
     colab_check,
     delete_none,
     error_analytics,
     format_ner_list,
     get_local_ip_address,
+    get_type_hints,
     ipython_check,
     kaggle_check,
     launch_analytics,
@@ -587,3 +590,51 @@ class TestAbspath:
     def test_abspath_symlink(self, mock_islink):
         resolved_path = str(abspath("../gradio/gradio/test_data/lion.jpg"))
         assert ".." in resolved_path
+
+
+class TestGetTypeHints:
+    def test_get_type_hints(self):
+        class F:
+            def __call__(self, s: str):
+                return s
+
+        class C:
+            def f(self, s: str):
+                return s
+
+        def f(s: str):
+            return s
+
+        class GenericObject:
+            pass
+
+        test_objs = [F(), C().f, f]
+
+        for x in test_objs:
+            hints = get_type_hints(x)
+            assert len(hints) == 1
+            assert hints["s"] == str
+
+        assert len(get_type_hints(GenericObject())) == 0
+
+
+class TestCheckFunctionInputsMatch:
+    def test_check_function_inputs_match(self):
+        class F:
+            def __call__(self, s: str, evt: EventData):
+                return s
+
+        class C:
+            def f(self, s: str, evt: EventData):
+                return s
+
+        def f(s: str, evt: EventData):
+            return s
+
+        test_objs = [F(), C().f, f]
+
+        with warnings.catch_warnings():
+            warnings.simplefilter("error")  # Ensure there're no warnings raised here.
+
+            for x in test_objs:
+                check_function_inputs_match(x, [None], False)