JS: Limit expression and statement nesting level

This is to prevent extremely deeply nested expressions and statements
make the code-generator run out of (native) stack space.

Task-number: QTBUG-71087
Change-Id: I8e1a20a361bff3e49101e535754546475a63ca18
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 24 insertions, 0 deletions

diff --git a/tests/auto/qml/v4misc/tst_v4misc.cpp b/tests/auto/qml/v4misc/tst_v4misc.cpp
index ecc3a4100c..71f0a42907 100644
--- a/tests/auto/qml/v4misc/tst_v4misc.cpp
+++ b/tests/auto/qml/v4misc/tst_v4misc.cpp
@@ -43,6 +43,8 @@ private slots:
 
     void subClassing_data();
     void subClassing();
+
+    void nestingDepth();
 };
 
 void tst_v4misc::tdzOptimizations_data()
@@ -173,6 +175,28 @@ void tst_v4misc::subClassing()
     QVERIFY(!result.isError());
 }
 
+void tst_v4misc::nestingDepth()
+{
+    { // left recursive
+        QString s(40000, '`');
+
+        QJSEngine engine;
+        QJSValue result = engine.evaluate(s);
+        QVERIFY(result.isError());
+        QCOMPARE(result.toString(), "SyntaxError: Maximum statement or expression depth exceeded");
+    }
+
+    { // right recursive
+        QString s(200000, '-');
+        s += "\nd";
+
+        QJSEngine engine;
+        QJSValue result = engine.evaluate(s);
+        QVERIFY(result.isError());
+        QCOMPARE(result.toString(), "SyntaxError: Maximum statement or expression depth exceeded");
+    }
+}
+
 QTEST_MAIN(tst_v4misc);
 
 #include "tst_v4misc.moc"