[Kaleidoscope] Remove RTTI use from chapters 7 and 8.

llvm-svn: 235541
diff --git a/llvm/examples/Kaleidoscope/Chapter7/toy.cpp b/llvm/examples/Kaleidoscope/Chapter7/toy.cpp
index 53ea51c..acf21f89 100644
--- a/llvm/examples/Kaleidoscope/Chapter7/toy.cpp
+++ b/llvm/examples/Kaleidoscope/Chapter7/toy.cpp
@@ -713,7 +713,10 @@
   // Special case '=' because we don't want to emit the LHS as an expression.
   if (Op == '=') {
     // Assignment requires the LHS to be an identifier.
-    VariableExprAST *LHSE = dynamic_cast<VariableExprAST *>(LHS);
+    // This assume we're building without RTTI because LLVM builds that way by
+    // default.  If you build LLVM with RTTI this can be changed to a
+    // dynamic_cast for automatic error checking.
+    VariableExprAST *LHSE = reinterpret_cast<VariableExprAST *>(LHS);
     if (!LHSE)
       return ErrorV("destination of '=' must be a variable");
     // Codegen the RHS.