Merge arg types from *args and **args

Author: A5rocks

mypy/typeops.py

@@ -464,15 +464,16 @@ def callable_corresponding_argument(
 
         # def right(a: int = ...) -> None: ...
         # def left(__a: int = ..., *, a: int = ...) -> None: ...
-        from mypy.subtypes import is_equivalent
+        from mypy.meet import meet_types
 
         if (
             not (by_name.required or by_pos.required)
             and by_pos.name is None
             and by_name.pos is None
-            and is_equivalent(by_name.typ, by_pos.typ)
         ):
-            return FormalArgument(by_name.name, by_pos.pos, by_name.typ, False)
+            return FormalArgument(
+                by_name.name, by_pos.pos, meet_types(by_pos.typ, by_name.typ), False
+            )
     return by_name if by_name is not None else by_pos
 
 

test-data/unit/check-overloading.test

@@ -6768,3 +6768,19 @@ class D(Generic[T]):
 a: D[str]  # E: Type argument "str" of "D" must be a subtype of "C"
 reveal_type(a.f(1))  # N: Revealed type is "builtins.int"
 reveal_type(a.f("x"))  # N: Revealed type is "builtins.str"
+
+[case testOverloadWithTwoRelevantArgsWithDifferentType]
+from typing import overload, Union
+
+@overload
+def set(year: int) -> None:
+    ...
+
+@overload
+def set() -> None:
+    ...
+
+# no error here:
+def set(*args: object, **kw: int) -> None:
+    pass
+[builtins fixtures/tuple.pyi]