Improving Flask stubs (#3003)

* Fix flask render_template and render_template_string stubs

* Add types for flask view function

* Import TracebackType from the right location

* Switch to bound typevar in route decorator stub

* Change render_template and render_template_string parameters to Text

third_party/2and3/flask/app.pyi

@@ -13,13 +13,51 @@ from .signals import appcontext_tearing_down, got_request_exception, request_fin
 from .templating import DispatchingJinjaLoader, Environment
 from .wrappers import Request, Response
 from .testing import FlaskClient
-from typing import Any, Callable, ContextManager, Dict, List, Optional, Type, TypeVar, Union, Text
+from types import TracebackType
+from typing import (
+    Any,
+    Callable,
+    ContextManager,
+    Dict,
+    List,
+    Optional,
+    Type,
+    TypeVar,
+    Union,
+    Text,
+    Tuple,
+    NoReturn,
+    Iterable,
+    ByteString
+)
 from datetime import timedelta
 
 def setupmethod(f: Any): ...
 
 _T = TypeVar('_T')
 
+
+_ExcInfo = Tuple[Optional[Type[BaseException]], Optional[BaseException], Optional[TracebackType]]
+_StartResponse = Callable[[str, List[Tuple[str, str]], Optional[_ExcInfo]], Callable[[bytes], Any]]
+_WSGICallable = Callable[[Dict[Text, Any], _StartResponse], Iterable[bytes]]
+
+_Status = Union[str, int]
+_Headers = Union[Dict[Any, Any], List[Tuple[Any, Any]]]
+_Body = Union[Text, ByteString, Response, _WSGICallable]
+
+_ViewFunc = Union[
+    Callable[..., Text],
+    Callable[..., ByteString],
+    Callable[..., NoReturn],
+    Callable[..., Response],
+    Callable[..., _WSGICallable],
+    Callable[..., Tuple[_Body, _Status, _Headers]],
+    Callable[..., Tuple[_Body, _Status]],
+    Callable[..., Tuple[_Body, _Headers]]
+]
+_VT = TypeVar('_VT', bound=_ViewFunc)
+
+
 class Flask(_PackageBoundObject):
     request_class: type = ...
     response_class: type = ...
@@ -96,8 +134,8 @@ class Flask(_PackageBoundObject):
     def make_null_session(self): ...
     def register_blueprint(self, blueprint: Blueprint, **options: Any) -> None: ...
     def iter_blueprints(self): ...
-    def add_url_rule(self, rule: str, endpoint: Optional[str] = ..., view_func: Callable[..., Any] = ..., provide_automatic_options: Optional[bool] = ..., **options: Any) -> None: ...
-    def route(self, rule: str, **options: Any) -> Callable[[Callable[..., _T]], Callable[..., _T]]: ...
+    def add_url_rule(self, rule: str, endpoint: Optional[str] = ..., view_func: _ViewFunc = ..., provide_automatic_options: Optional[bool] = ..., **options: Any) -> None: ...
+    def route(self, rule: str, **options: Any) -> Callable[[_VT], _VT]: ...
     def endpoint(self, endpoint: str) -> Callable[[Callable[..., _T]], Callable[..., _T]]: ...
     def errorhandler(self, code_or_exception: Union[int, Type[Exception]]) -> Callable[[Callable[..., _T]], Callable[..., _T]]: ...
     def register_error_handler(self, code_or_exception: Union[int, Type[Exception]], f: Callable[..., Any]) -> None: ...

third_party/2and3/flask/blueprints.pyi

@@ -3,9 +3,11 @@
 # NOTE: This dynamically typed stub was automatically generated by stubgen.
 
 from .helpers import _PackageBoundObject
+from .app import _ViewFunc
 from typing import Any, Callable, Optional, Type, TypeVar, Union
 
 _T = TypeVar('_T')
+_VT = TypeVar('_VT', bound=_ViewFunc)
 
 class BlueprintSetupState:
     app: Any = ...
@@ -16,7 +18,7 @@ class BlueprintSetupState:
     url_prefix: Any = ...
     url_defaults: Any = ...
     def __init__(self, blueprint: Any, app: Any, options: Any, first_registration: Any) -> None: ...
-    def add_url_rule(self, rule: str, endpoint: Optional[str] = ..., view_func: Callable[..., Any] = ..., **options: Any) -> None: ...
+    def add_url_rule(self, rule: str, endpoint: Optional[str] = ..., view_func: _ViewFunc = ..., **options: Any) -> None: ...
 
 class Blueprint(_PackageBoundObject):
     warn_on_modifications: bool = ...
@@ -37,8 +39,8 @@ class Blueprint(_PackageBoundObject):
     def record_once(self, func: Any): ...
     def make_setup_state(self, app: Any, options: Any, first_registration: bool = ...): ...
     def register(self, app: Any, options: Any, first_registration: bool = ...) -> None: ...
-    def route(self, rule: str, **options: Any) -> Callable[[Callable[..., Any]], Callable[..., Any]]: ...
-    def add_url_rule(self, rule: str, endpoint: Optional[str] = ..., view_func: Callable[..., Any] = ..., **options: Any) -> None: ...
+    def route(self, rule: str, **options: Any) -> Callable[[_VT], _VT]: ...
+    def add_url_rule(self, rule: str, endpoint: Optional[str] = ..., view_func: _ViewFunc = ..., **options: Any) -> None: ...
     def endpoint(self, endpoint: str) -> Callable[[Callable[..., _T]], Callable[..., _T]]: ...
     def app_template_filter(self, name: Optional[Any] = ...): ...
     def add_app_template_filter(self, f: Any, name: Optional[Any] = ...) -> None: ...

third_party/2and3/flask/templating.pyi

@@ -5,7 +5,7 @@
 from .globals import _app_ctx_stack, _request_ctx_stack
 from .signals import before_render_template, template_rendered
 from jinja2 import BaseLoader, Environment as BaseEnvironment
-from typing import Any
+from typing import Any, Text, Iterable, Union
 
 class Environment(BaseEnvironment):
     app: Any = ...
@@ -17,5 +17,8 @@ class DispatchingJinjaLoader(BaseLoader):
     def get_source(self, environment: Any, template: Any): ...
     def list_templates(self): ...
 
-def render_template(template_name_or_list: Any, **context: Any): ...
-def render_template_string(source: Any, **context: Any): ...
+def render_template(
+    template_name_or_list: Union[Text, Iterable[Text]],
+    **context: Any
+) -> Text: ...
+def render_template_string(source: Text, **context: Any) -> Text: ...