Revert "abi compatibility"

This reverts commit 9e9ba85.

vyper/semantics/types/function.py

@@ -496,16 +496,11 @@ def implements(self, other: "ContractFunctionT") -> bool:
         if len(arguments) != len(other_arguments):
             return False
         for atyp, btyp in zip(arguments, other_arguments):
-            labi = atyp.abi_type
-            rabi = btyp.abi_type
-            if labi.selector_name() != rabi.selector_name():
+            if not atyp.compare_type(btyp):
                 return False
 
-        if return_type is not None:
-            if other_return_type is None:
-                return False
-            if return_type.abi_type.selector_name() != other_return_type.abi_type.selector_name():
-                return False
+        if return_type and not return_type.compare_type(other_return_type):  # type: ignore
+            return False
 
         return self.mutability == other.mutability