Change the AST representation of operations on Objective-C

property references to use a new PseudoObjectExpr
expression which pairs a syntactic form of the expression
with a set of semantic expressions implementing it.
This should significantly reduce the complexity required
elsewhere in the compiler to deal with these kinds of
expressions (e.g. IR generation's special l-value kind,
the static analyzer's Message abstraction), at the lower
cost of specifically dealing with the odd AST structure
of these expressions.  It should also greatly simplify
efforts to implement similar language features in the
future, most notably Managed C++'s properties and indexed
properties.

Most of the effort here is in dealing with the various
clients of the AST.  I've gone ahead and simplified the
ObjC rewriter's use of properties;  other clients, like
IR-gen and the static analyzer, have all the old
complexity *and* all the new complexity, at least
temporarily.  Many thanks to Ted for writing and advising
on the necessary changes to the static analyzer.

I've xfailed a small diagnostics regression in the static
analyzer at Ted's request.

llvm-svn: 143867

1 files changed, 16 insertions, 0 deletions

diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 5596a9a6caa..f55e2a706bb 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -6103,6 +6103,22 @@ TreeTransform<Derived>::TransformOpaqueValueExpr(OpaqueValueExpr *E) {
 
 template<typename Derived>
 ExprResult
+TreeTransform<Derived>::TransformPseudoObjectExpr(PseudoObjectExpr *E) {
+  // Rebuild the syntactic form.
+  ExprResult result = getDerived().TransformExpr(E->getSyntacticForm());
+  if (result.isInvalid()) return ExprError();
+
+  // If that gives us a pseudo-object result back, the pseudo-object
+  // expression must have been an lvalue-to-rvalue conversion which we
+  // should reapply.
+  if (result.get()->hasPlaceholderType(BuiltinType::PseudoObject))
+    result = SemaRef.checkPseudoObjectRValue(result.take());
+
+  return result;
+}
+
+template<typename Derived>
+ExprResult
 TreeTransform<Derived>::TransformUnaryExprOrTypeTraitExpr(
                                                 UnaryExprOrTypeTraitExpr *E) {
   if (E->isArgumentType()) {