1 files changed, 4 insertions, 1 deletions
diff --git a/examples/Kaleidoscope/Chapter4/toy.cpp b/examples/Kaleidoscope/Chapter4/toy.cpp
index 0e41cc1..4d56c0f 100644
--- a/examples/Kaleidoscope/Chapter4/toy.cpp
+++ b/examples/Kaleidoscope/Chapter4/toy.cpp
@@ -91,10 +91,13 @@ static int gettok() {
 /// ExprAST - Base class for all expression nodes.
 class ExprAST {
 public:
-  virtual ~ExprAST() {}
+  virtual ~ExprAST();
   virtual Value *Codegen() = 0;
 };
 
+// Provide out-of-line definition to prevent weak vtable.
+ExprAST::~ExprAST() {}
+
 /// NumberExprAST - Expression class for numeric literals like "1.0".
 class NumberExprAST : public ExprAST {
   double Val;