Fixes raise CustomError creationg with __init__ with arguments (#11125)

Fixes #11089

Author: sobolevn

mypy/checker.py

@@ -3424,6 +3424,10 @@ def type_check_raise(self, e: Expression, s: RaiseStmt,
             expected_type.items.append(TupleType([any_type, any_type, any_type], tuple_type))
         self.check_subtype(typ, expected_type, s, message_registry.INVALID_EXCEPTION)
 
+        if isinstance(typ, FunctionLike):
+            # https://github.com/python/mypy/issues/11089
+            self.expr_checker.check_call(typ, [], [], e)
+
     def visit_try_stmt(self, s: TryStmt) -> None:
         """Type check a try statement."""
         # Our enclosing frame will get the result if the try/except falls through.

test-data/unit/check-statements.test

@@ -406,8 +406,7 @@ class MyError(BaseException): pass
 [out]
 main:5: error: Exception must be derived from BaseException
 
-[case testRaiseClassobject]
-import typing
+[case testRaiseClassObject]
 class A: pass
 class MyError(BaseException): pass
 def f(): pass
@@ -418,6 +417,33 @@ raise object # E: Exception must be derived from BaseException
 raise f # E: Exception must be derived from BaseException
 [builtins fixtures/exception.pyi]
 
+[case testRaiseClassObjectCustomInit]
+class MyBaseError(BaseException):
+    def __init__(self, required) -> None:
+        ...
+class MyError(Exception):
+    def __init__(self, required1, required2) -> None:
+        ...
+class MyKwError(Exception):
+    def __init__(self, *, kwonly) -> None:
+        ...
+class MyErrorWithDefault(Exception):
+    def __init__(self, optional=1) -> None:
+        ...
+raise BaseException
+raise Exception
+raise BaseException(1)
+raise Exception(2)
+raise MyBaseError(4)
+raise MyError(5, 6)
+raise MyKwError(kwonly=7)
+raise MyErrorWithDefault(8)
+raise MyErrorWithDefault
+raise MyBaseError  # E: Too few arguments for "MyBaseError"
+raise MyError  # E: Too few arguments for "MyError"
+raise MyKwError  # E: Missing named argument "kwonly" for "MyKwError"
+[builtins fixtures/exception.pyi]
+
 [case testRaiseExceptionType]
 import typing
 x = None # type: typing.Type[BaseException]