Qt SCXML: Fix HistoryState crash

Use the initial state of the parent state as the transition of a
history state, if the parent state of the history state was not
entered before.

Task-number: QTBUG-89845
Fixes: QTBUG-76091
Change-Id: I4c8a5898406bdf2931424b3cf012e42e422431ae
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
(cherry picked from commit e868c6fa904a2b31b253c07739564fc9e7f1b76c)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

4 files changed, 84 insertions, 2 deletions

diff --git a/src/scxml/qscxmlstatemachine.cpp b/src/scxml/qscxmlstatemachine.cpp
index a875a53..d90caa7 100644
--- a/src/scxml/qscxmlstatemachine.cpp
+++ b/src/scxml/qscxmlstatemachine.cpp
@@ -1247,7 +1247,15 @@ void QScxmlStateMachinePrivate::addDescendantStatesToEnter(
                 addAncestorStatesToEnter(s, state.parent, statesToEnter, statesForDefaultEntry,
                                          defaultHistoryContent);
         } else {
-            const auto transitionIdx = m_stateTable->array(state.transitions)[0];
+            int transitionIdx = StateTable::InvalidIndex;
+            if (state.transitions == StateTable::InvalidIndex) {
+                int parentInitialTransition = m_stateTable->state(state.parent).initialTransition;
+                if (parentInitialTransition == StateTable::InvalidIndex)
+                    return;
+                transitionIdx = parentInitialTransition;
+            } else {
+                transitionIdx = m_stateTable->array(state.transitions)[0];
+            }
             const auto &defaultHistoryTransition = m_stateTable->transition(transitionIdx);
             defaultHistoryContent->operator[](state.parent) =
                     defaultHistoryTransition.transitionInstructions;
@@ -1457,7 +1465,7 @@ void QScxmlStateMachinePrivate::getEffectiveTargetStates(OrderedSet *targets,
                 for (int historyState : historyValueIter.value()) {
                     targets->add(historyState);
                 }
-            } else {
+            } else if (state.transitions != StateTable::InvalidIndex) {
                 getEffectiveTargetStates(targets, m_stateTable->array(state.transitions)[0]);
             }
         } else {
diff --git a/tests/auto/compiled/CMakeLists.txt b/tests/auto/compiled/CMakeLists.txt
index 39ceb72..1a22044 100644
--- a/tests/auto/compiled/CMakeLists.txt
+++ b/tests/auto/compiled/CMakeLists.txt
@@ -39,6 +39,7 @@ qt6_add_statecharts(tst_compiled
     initialhistory.scxml
     connection.scxml
     topmachine.scxml
+    historyState.scxml
 )
 
 #### Keys ignored in scope 1:.:.:compiled.pro:<TRUE>:
diff --git a/tests/auto/compiled/historyState.scxml b/tests/auto/compiled/historyState.scxml
new file mode 100644
index 0000000..c1f58ad
--- /dev/null
+++ b/tests/auto/compiled/historyState.scxml
@@ -0,0 +1,57 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<scxml xmlns="http://www.w3.org/2005/07/scxml" version="1.0" binding="early" xmlns:qt="http://www.qt.io/2015/02/scxml-ext" name="HistoryState" qt:editorversion="4.9.0">
+    <state id="Off">
+        <transition type="external" event="toOn" target="On">
+        </transition>
+        <transition type="external" event="toHistory" target="History_1">
+        </transition>
+        <onentry>
+            <log label="Off" expr="onentry"/>
+        </onentry>
+        <onexit>
+            <log label="Off" expr="onexit"/>
+        </onexit>
+    </state>
+    <state id="On" initial="Beta">
+        <state id="Alpha">
+            <transition type="external" event="toBeta" target="Beta">
+            </transition>
+            <onentry>
+                <log label="Alpha" expr="onentry"/>
+            </onentry>
+            <onexit>
+                <log label="Alpha" expr="onexit"/>
+            </onexit>
+        </state>
+        <state id="Beta">
+            <transition type="external" event="toDelta" target="Delta">
+            </transition>
+            <onentry>
+                <log label="Beta" expr="onentry"/>
+            </onentry>
+            <onexit>
+                <log label="Beta" expr="onexit"/>
+            </onexit>
+        </state>
+        <history type="shallow" id="History_1">
+        </history>
+        <state id="Delta">
+            <transition type="external" event="toAlpha" target="Alpha">
+            </transition>
+            <onentry>
+                <log label="Delta" expr="onentry"/>
+            </onentry>
+            <onexit>
+                <log label="Delta" expr="onexit"/>
+            </onexit>
+        </state>
+        <transition type="external" event="toOff" target="Off">
+        </transition>
+        <onentry>
+            <log label="On" expr="onentry"/>
+        </onentry>
+        <onexit>
+            <log label="On" expr="onexit"/>
+        </onexit>
+    </state>
+</scxml>
diff --git a/tests/auto/compiled/tst_compiled.cpp b/tests/auto/compiled/tst_compiled.cpp
index 3d6c071..a99688b 100644
--- a/tests/auto/compiled/tst_compiled.cpp
+++ b/tests/auto/compiled/tst_compiled.cpp
@@ -39,6 +39,7 @@
 #include "eventnames1.h"
 #include "connection.h"
 #include "topmachine.h"
+#include "historyState.h"
 
 enum { SpyWaitTime = 8000 };
 
@@ -56,6 +57,7 @@ private Q_SLOTS:
     void topMachine();
     void topMachineDynamic();
     void publicSignals();
+    void historyState();
 };
 
 void tst_Compiled::stateNames()
@@ -306,6 +308,20 @@ void tst_Compiled::publicSignals()
     QCOMPARE(aChanged.access(), QMetaMethod::Public);
 }
 
+void tst_Compiled::historyState()
+{
+    HistoryState historyStateSM;
+    QSignalSpy stableStateSpy(&historyStateSM, SIGNAL(reachedStableState()));
+    historyStateSM.start();
+
+    stableStateSpy.wait(5000);
+    QCOMPARE(historyStateSM.activeStateNames(), QStringList(QLatin1String("Off")));
+
+    historyStateSM.submitEvent("toHistory");
+    stableStateSpy.wait(5000);
+    QCOMPARE(historyStateSM.activeStateNames(), QStringList(QLatin1String("Beta")));
+}
+
 QTEST_MAIN(tst_Compiled)
 
 #include "tst_compiled.moc"