V4: Don't call methods on nullptr

The root node of a sparse array can be null.

Pick-to: 6.7 6.5 6.2 5.15
Fixes: QTBUG-123596
Change-Id: I5ea7fd73aeec460082d0cf19c7fc8a01993ed1f9
Reviewed-by: Semih Yavuz <semih.yavuz@qt.io>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 26 insertions, 18 deletions

diff --git a/src/qml/jsruntime/qv4sparsearray_p.h b/src/qml/jsruntime/qv4sparsearray_p.h
index db23c0af75..7da42a4985 100644
--- a/src/qml/jsruntime/qv4sparsearray_p.h
+++ b/src/qml/jsruntime/qv4sparsearray_p.h
@@ -110,8 +110,8 @@ struct Q_QML_EXPORT SparseArray
 {
     SparseArray();
     ~SparseArray() {
-        if (root())
-            freeTree(header.left, alignof(SparseArrayNode));
+        if (SparseArrayNode *n = root())
+            freeTree(n, alignof(SparseArrayNode));
     }
 
     SparseArray(const SparseArray &other);
@@ -287,37 +287,45 @@ inline QList<int> SparseArray::keys() const
 
 inline const SparseArrayNode *SparseArray::lowerBound(uint akey) const
 {
-    const SparseArrayNode *lb = root()->lowerBound(akey);
-    if (!lb)
-        lb = end();
-    return lb;
+    if (SparseArrayNode *n = root()) {
+        if (const SparseArrayNode *lb = n->lowerBound(akey))
+            return lb;
+    }
+
+    return end();
 }
 
 
 inline SparseArrayNode *SparseArray::lowerBound(uint akey)
 {
-    SparseArrayNode *lb = root()->lowerBound(akey);
-    if (!lb)
-        lb = end();
-    return lb;
+    if (SparseArrayNode *n = root()) {
+        if (SparseArrayNode *lb = n->lowerBound(akey))
+            return lb;
+    }
+
+    return end();
 }
 
 
 inline const SparseArrayNode *SparseArray::upperBound(uint akey) const
 {
-    const SparseArrayNode *ub = root()->upperBound(akey);
-    if (!ub)
-        ub = end();
-    return ub;
+    if (SparseArrayNode *n = root()) {
+        if (const SparseArrayNode *ub = n->upperBound(akey))
+            return ub;
+    }
+
+    return end();
 }
 
 
 inline SparseArrayNode *SparseArray::upperBound(uint akey)
 {
-    SparseArrayNode *ub = root()->upperBound(akey);
-    if (!ub)
-        ub = end();
-    return ub;
+    if (SparseArrayNode *n = root()) {
+        if (SparseArrayNode *ub = n->upperBound(akey))
+            return ub;
+    }
+
+    return end();
 }
 
 }