Change the representation of builtin functions in the AST
(__builtin_* etc.) so that it isn't possible to take their address.
Specifically, introduce a new type to represent a reference to a builtin
function, and a new cast kind to convert it to a function pointer in the
operand of a call.  Fixes PR13195.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@162962 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 8760c5e..137f3e1 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -1232,14 +1232,14 @@
       NewBuiltinDecl,
       /*enclosing*/ false,
       DRE->getLocation(),
-      NewBuiltinDecl->getType(),
+      Context.BuiltinFnTy,
       DRE->getValueKind());
 
   // Set the callee in the CallExpr.
-  // FIXME: This leaks the original parens and implicit casts.
-  ExprResult PromotedCall = UsualUnaryConversions(NewDRE);
-  if (PromotedCall.isInvalid())
-    return ExprError();
+  // FIXME: This loses syntactic information.
+  QualType CalleePtrTy = Context.getPointerType(NewBuiltinDecl->getType());
+  ExprResult PromotedCall = ImpCastExprToType(NewDRE, CalleePtrTy,
+                                              CK_BuiltinFnToFnPtr);
   TheCall->setCallee(PromotedCall.take());
 
   // Change the result type of the call to match the original value type. This