Fix crash when QML engine warning handler feeds errors back into QML

When a QQmlEngine warning handler that's called during component
instantiation results in subsequent component instantiations, either via
the signal or via a Qt message handler like in the bug report, then we
might end up modifying the linked list of errored bindings before
returning from the QQmlEnginePrivate::warning() call. The easy fix is to
extract the QQmlError, unlink the delayed error from the linked list and
then deliver the error to the QQmlEngine.

Change-Id: I6b7be61b57b35636282595937046ff76091144a3
Task-number: QTBUG-53293
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 4 insertions, 8 deletions

diff --git a/src/qml/qml/qqmlincubator.cpp b/src/qml/qml/qqmlincubator.cpp
index 4546a4423f..df168960c6 100644
--- a/src/qml/qml/qqmlincubator.cpp
+++ b/src/qml/qml/qqmlincubator.cpp
@@ -367,10 +367,8 @@ finishIncubate:
         enginePriv->inProgressCreations--;
 
         if (0 == enginePriv->inProgressCreations) {
-            while (enginePriv->erroredBindings) {
-                enginePriv->warning(enginePriv->erroredBindings);
-                enginePriv->erroredBindings->removeError();
-            }
+            while (enginePriv->erroredBindings)
+                enginePriv->warning(enginePriv->erroredBindings->removeError());
         }
     } else if (!creator.isNull()) {
         vmeGuard.guard(creator.data());
@@ -575,10 +573,8 @@ void QQmlIncubator::clear()
 
         enginePriv->inProgressCreations--;
         if (0 == enginePriv->inProgressCreations) {
-            while (enginePriv->erroredBindings) {
-                enginePriv->warning(enginePriv->erroredBindings);
-                enginePriv->erroredBindings->removeError();
-            }
+            while (enginePriv->erroredBindings)
+                enginePriv->warning(enginePriv->erroredBindings->removeError());
         }
     }