Fix deferred case

mypy/checker.py

@@ -644,7 +644,11 @@ def _visit_overloaded_func_def(self, defn: OverloadedFuncDef) -> None:
             defn.impl.accept(self)
         if defn.info:
             found_method_base_classes = self.check_method_override(defn)
-            if defn.is_explicit_override and not found_method_base_classes:
+            if (
+                defn.is_explicit_override
+                and not found_method_base_classes
+                and found_method_base_classes is not None
+            ):
                 self.msg.no_overridable_method(defn.name, defn)
             elif (
                 found_method_base_classes
@@ -4760,7 +4764,11 @@ def visit_decorator(self, e: Decorator) -> None:
         # For overloaded functions we already checked override for overload as a whole.
         if e.func.info and not e.func.is_dynamic() and not e.is_overload:
             found_method_base_classes = self.check_method_override(e)
-            if e.func.is_explicit_override and not found_method_base_classes:
+            if (
+                e.func.is_explicit_override
+                and not found_method_base_classes
+                and found_method_base_classes is not None
+            ):
                 self.msg.no_overridable_method(e.func.name, e.func)
             elif (
                 found_method_base_classes

test-data/unit/check-functions.test

@@ -3001,6 +3001,32 @@ class C(A):
     def f(self, y: int | str) -> str: pass
 [typing fixtures/typing-override.pyi]
 
+[case explicitOverrideCyclicDependency]
+# flags: --python-version 3.12
+import b
+[file a.py]
+from typing import override
+import b
+import c
+
+class A(b.B):
+    @override  # This is fine
+    @c.deco
+    def meth(self) -> int: ...
+[file b.py]
+import a
+import c
+
+class B:
+    @c.deco
+    def meth(self) -> int: ...
+[file c.py]
+from typing import TypeVar, Tuple, Callable
+T = TypeVar('T')
+def deco(f: Callable[..., T]) -> Callable[..., Tuple[T, int]]: ...
+[builtins fixtures/tuple.pyi]
+[typing fixtures/typing-override.pyi]
+
 [case requireExplicitOverrideMethod]
 # flags: --strict-override-decorator --python-version 3.12
 from typing import override

test-data/unit/fixtures/typing-override.pyi

@@ -8,6 +8,7 @@ Optional = 0
 Self = 0
 Tuple = 0
 ClassVar = 0
+Callable = 0
 
 T = TypeVar('T')
 T_co = TypeVar('T_co', covariant=True)