Fix primer error, minor polish.

mypy/checkmember.py

@@ -319,11 +319,7 @@ def analyze_instance_member_access(
             mx.msg.cant_assign_to_method(mx.context)
         signature = function_type(method, mx.named_type("builtins.function"))
         signature = freshen_all_functions_type_vars(signature)
-        if name == "__new__" or method.is_static:
-            # __new__ is special and behaves like a static method -- don't strip
-            # the first argument.
-            pass
-        else:
+        if not method.is_static:
             if name != "__call__":
                 # TODO: use proper treatment of special methods on unions instead
                 #       of this hack here and below (i.e. mx.self_type).

mypy/nodes.py

@@ -510,7 +510,7 @@ class FuncBase(Node):
         "info",
         "is_property",
         "is_class",  # Uses "@classmethod" (explicit or implicit)
-        "is_static",  # Uses "@staticmethod"
+        "is_static",  # Uses "@staticmethod" (explicit or implicit)
         "is_final",  # Uses "@final"
         "is_explicit_override",  # Uses "@override"
         "_fullname",

mypy/semanal.py

@@ -1383,7 +1383,7 @@ def analyze_function_body(self, defn: FuncItem) -> None:
                 # The first argument of a non-static, non-class method is like 'self'
                 # (though the name could be different), having the enclosing class's
                 # instance type.
-                if is_method and not defn.is_static and defn.arguments:
+                if is_method and (not defn.is_static or defn.name == "__new__") and defn.arguments:
                     if not defn.is_class:
                         defn.arguments[0].variable.is_self = True
                     else: