[AST] Add a method to get a call type from an ObjCMessageExpr

Due to references, expression type does not always correspond to an
expected method return type (e.g. for a method returning int & the
expression type of the call would still be int).
We have a helper method for getting the expected type on CallExpr, but
not on ObjCMessageExpr.

Differential Revision: https://reviews.llvm.org/D57204

llvm-svn: 352147

1 files changed, 25 insertions, 0 deletions

diff --git a/clang/lib/AST/ExprObjC.cpp b/clang/lib/AST/ExprObjC.cpp
index c31b5de2a5b..584aa8c1fbe 100644
--- a/clang/lib/AST/ExprObjC.cpp
+++ b/clang/lib/AST/ExprObjC.cpp
@@ -292,6 +292,31 @@ void ObjCMessageExpr::getSelectorLocs(
     SelLocs.push_back(getSelectorLoc(i));
 }
 
+
+QualType ObjCMessageExpr::getCallReturnType(ASTContext &Ctx) const {
+  if (const ObjCMethodDecl *MD = getMethodDecl()) {
+    QualType QT = MD->getReturnType();
+    if (QT == Ctx.getObjCInstanceType()) {
+      // instancetype corresponds to expression types.
+      return getType();
+    }
+    return QT;
+  }
+
+  // Expression type might be different from an expected call return type,
+  // as expression type would never be a reference even if call returns a
+  // reference. Reconstruct the original expression type.
+  QualType QT = getType();
+  switch (getValueKind()) {
+  case VK_LValue:
+    return Ctx.getLValueReferenceType(QT);
+  case VK_XValue:
+    return Ctx.getRValueReferenceType(QT);
+  case VK_RValue:
+    return QT;
+  }
+}
+
 SourceRange ObjCMessageExpr::getReceiverRange() const {
   switch (getReceiverKind()) {
   case Instance: