2 files changed, 13 insertions, 2 deletions
diff --git a/src/qml/compiler/qv4bytecodegenerator_p.h b/src/qml/compiler/qv4bytecodegenerator_p.h
index 1895a34a68..5244c443c4 100644
--- a/src/qml/compiler/qv4bytecodegenerator_p.h
+++ b/src/qml/compiler/qv4bytecodegenerator_p.h
@@ -186,13 +186,13 @@ QT_WARNING_POP
 
     Q_REQUIRED_RESULT Jump jumpNotUndefined()
     {
-        Instruction::JumpNotUndefined data;
+        Instruction::JumpNotUndefined data{};
         return addJumpInstruction(data);
     }
 
     Q_REQUIRED_RESULT Jump jumpNoException()
     {
-        Instruction::JumpNoException data;
+        Instruction::JumpNoException data{};
         return addJumpInstruction(data);
     }
 
diff --git a/src/qml/compiler/qv4codegen.cpp b/src/qml/compiler/qv4codegen.cpp
index 4588690307..5a0dc11fbf 100644
--- a/src/qml/compiler/qv4codegen.cpp
+++ b/src/qml/compiler/qv4codegen.cpp
@@ -2927,6 +2927,17 @@ bool Codegen::visit(YieldExpression *ast)
         return false;
     }
 
+    auto innerMostCurentFunctionContext = _context;
+    while (innerMostCurentFunctionContext && innerMostCurentFunctionContext->contextType != ContextType::Function)
+        innerMostCurentFunctionContext = innerMostCurentFunctionContext->parent;
+
+    Q_ASSERT(innerMostCurentFunctionContext); // yield outside function would have been rejected by parser
+
+    if (!innerMostCurentFunctionContext->isGenerator) {
+        throwSyntaxError(ast->firstSourceLocation(), QLatin1String("Yield is only valid in generator functions"));
+        return false;
+    }
+
     RegisterScope scope(this);
     TailCallBlocker blockTailCalls(this);
     Reference expr = ast->expression ? expression(ast->expression) : Reference::fromConst(this, Encode::undefined());