Merge branch '2.0.x'

src/flask/ctx.py

@@ -130,7 +130,15 @@ def after_this_request(f: AfterRequestCallable) -> AfterRequestCallable:
 
     .. versionadded:: 0.9
     """
-    _request_ctx_stack.top._after_request_functions.append(f)
+    top = _request_ctx_stack.top
+
+    if top is None:
+        raise RuntimeError(
+            "This decorator can only be used when a request context is"
+            " active, such as within a view function."
+        )
+
+    top._after_request_functions.append(f)
     return f
 
 
@@ -159,12 +167,13 @@ def copy_current_request_context(f: t.Callable) -> t.Callable:
     .. versionadded:: 0.10
     """
     top = _request_ctx_stack.top
+
     if top is None:
         raise RuntimeError(
-            "This decorator can only be used at local scopes "
-            "when a request context is on the stack.  For instance within "
-            "view functions."
+            "This decorator can only be used when a request context is"
+            " active, such as within a view function."
         )
+
     reqctx = top.copy()
 
     def wrapper(*args, **kwargs):

src/flask/json/__init__.py

@@ -74,6 +74,11 @@ def _dump_arg_defaults(
         if bp is not None and bp.json_encoder is not None:
             cls = bp.json_encoder
 
+        # Only set a custom encoder if it has custom behavior. This is
+        # faster on PyPy.
+        if cls is not _json.JSONEncoder:
+            kwargs.setdefault("cls", cls)
+
         kwargs.setdefault("cls", cls)
         kwargs.setdefault("ensure_ascii", app.config["JSON_AS_ASCII"])
         kwargs.setdefault("sort_keys", app.config["JSON_SORT_KEYS"])
@@ -95,9 +100,10 @@ def _load_arg_defaults(
         if bp is not None and bp.json_decoder is not None:
             cls = bp.json_decoder
 
-        kwargs.setdefault("cls", cls)
-    else:
-        kwargs.setdefault("cls", JSONDecoder)
+        # Only set a custom decoder if it has custom behavior. This is
+        # faster on PyPy.
+        if cls not in {JSONDecoder, _json.JSONDecoder}:
+            kwargs.setdefault("cls", cls)
 
 
 def dumps(obj: t.Any, app: t.Optional["Flask"] = None, **kwargs: t.Any) -> str: