Here, have some code

Author: root

mypy/checker.py

@@ -3023,10 +3023,14 @@ def visit_decorator(self, e: Decorator) -> None:
                                                    callable_name=fullname)
         self.check_untyped_after_decorator(sig, e.func)
         sig = set_callable_name(sig, e.func)
-        e.var.type = sig
-        e.var.is_ready = True
         if e.func.is_property:
+            assert isinstance(sig, CallableType)
+            sig = sig.ret_type
             self.check_incompatible_property_override(e)
+        e.var.type = sig
+        e.var.is_ready = True
+        if isinstance(sig, CallableType):
+            e.is_callable = True
         if e.func.info and not e.func.is_dynamic():
             self.check_method_override(e)
 

mypy/checkmember.py

@@ -557,8 +557,7 @@ def analyze_class_attribute_access(itype: Instance,
             return chk.handle_partial_var_type(t, is_lvalue, symnode, context)
         if not is_method and (isinstance(t, TypeVarType) or get_type_vars(t)):
             msg.fail(messages.GENERIC_INSTANCE_VAR_CLASS_ACCESS, context)
-        is_classmethod = ((is_decorated and cast(Decorator, node.node).func.is_class)
-                          or (isinstance(node.node, FuncBase) and node.node.is_class))
+        is_classmethod = isinstance(node.node, FuncBase) and node.node.is_class
         result = add_class_tvars(t, itype, is_classmethod, builtin_type, original_type)
         if not is_lvalue:
             result = analyze_descriptor_access(original_type, result, builtin_type,

mypy/errors.py

@@ -594,6 +594,8 @@ def report_internal_error(err: Exception, file: Optional[str], line: int,
         pdb.post_mortem(sys.exc_info()[2])
 
     # If requested, print traceback, else print note explaining how to get one.
+    if options.raise_exceptions:
+        raise err
     if not options.show_traceback:
         if not options.pdb:
             print('{}: note: please use --show-traceback to print a traceback '

mypy/fastparse.py

@@ -871,7 +871,8 @@ def is_star2arg(k: ast3.keyword) -> bool:
             [k.value for k in n.keywords])
         arg_kinds = ([ARG_STAR if isinstance(a, ast3.Starred) else ARG_POS for a in n.args] +
                      [ARG_STAR2 if is_star2arg(k) else ARG_NAMED for k in n.keywords])
-        return CallExpr(self.visit(n.func),
+        expr = self.visit(n.func)
+        return CallExpr(expr,
                         arg_types,
                         arg_kinds,
                         cast(List[Optional[str]], [None] * len(n.args)) +

mypy/main.py

@@ -618,6 +618,9 @@ def add_invertible_flag(flag: str,
     internals_group.add_argument(
         '--show-traceback', '--tb', action='store_true',
         help="Show traceback on fatal error")
+    internals_group.add_argument(
+        '--raise-exceptions', action='store_true', help="Raise exception on fatal error"
+    )
     internals_group.add_argument(
         '--custom-typing', metavar='MODULE', dest='custom_typing_module',
         help="Use a custom typing module")

mypy/nodes.py

@@ -383,7 +383,18 @@ def __str__(self) -> str:
 ]  # type: Final
 
 
-class FuncBase(Node):
+class FuncBaseMeta(type):
+    def __instancecheck__(self, instance):
+        if isinstance(instance, Decorator):
+            if instance.is_overload:
+                return issubclass(OverloadedFuncDef, self) and instance.is_callable
+            else:
+                return issubclass(FuncBase, self) and instance.is_callable
+        else:
+            return super().__instancecheck__(instance)
+
+
+class FuncBase(Node, metaclass=FuncBaseMeta):
     """Abstract base class for function-like nodes"""
 
     __slots__ = ('type',
@@ -657,6 +668,7 @@ class Decorator(SymbolNode, Statement):
     # TODO: This is mostly used for the type; consider replacing with a 'type' attribute
     var = None  # type: Var                     # Represents the decorated function obj
     is_overload = False
+    is_callable = False
 
     def __init__(self, func: FuncDef, decorators: List[Expression],
                  var: 'Var') -> None:
@@ -672,6 +684,18 @@ def name(self) -> str:
     def fullname(self) -> Bogus[str]:
         return self.func.fullname()
 
+    @property
+    def items(self):
+        return self.func.items
+
+    @property
+    def is_property(self) -> bool:
+        return self.func.is_property
+
+    @property
+    def is_class(self) -> bool:
+        return self.func.is_class
+
     @property
     def is_final(self) -> bool:
         return self.func.is_final
@@ -2299,7 +2323,7 @@ def __repr__(self) -> str:
     def has_readable_member(self, name: str) -> bool:
         return self.get(name) is not None
 
-    def get_method(self, name: str) -> Optional[FuncBase]:
+    def get_method(self, name: str) -> Union[FuncBase, Decorator, None]:
         for cls in self.mro:
             if name in cls.names:
                 node = cls.names[name].node

mypy/options.py

@@ -196,6 +196,7 @@ def __init__(self) -> None:
         self.verbosity = 0  # More verbose messages (for troubleshooting)
         self.pdb = False
         self.show_traceback = False
+        self.raise_exceptions = False
         self.dump_type_stats = False
         self.dump_inference_stats = False
 

mypy/semanal.py

@@ -2514,6 +2514,7 @@ def visit_decorator(self, dec: Decorator) -> None:
                 self.check_decorated_function_is_method('classmethod', dec)
             elif (refers_to_fullname(d, 'builtins.property') or
                   refers_to_fullname(d, 'abc.abstractproperty')):
+                # TODO: Stop treating properties as special cases and treat as generalized descriptors
                 removed.append(i)
                 dec.func.is_property = True
                 dec.var.is_property = True

mypy_self_check.ini

@@ -8,7 +8,7 @@ disallow_any_generics = True
 disallow_any_unimported = True
 warn_redundant_casts = True
 warn_unused_configs = True
-show_traceback = True
+raise_exceptions = True
 
 # needs py2 compatibility
 [mypy-mypy.test.testextensions]