[Sema] Call CheckPlaceholderExpr to resolve typeof or decltype

placeholder expressions while an unevaluated context is still on the
expression evaluation context stack.

This prevents recordUseOfWeek from being called when a weak variable is
used as an operand of a decltype or a typeof expression and fixes
spurious -Warc-repeated-use-of-weak warnings.

rdar://problem/45742525

Differential Revision: https://reviews.llvm.org/D55662

llvm-svn: 350887

1 files changed, 1 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaExprObjC.cpp b/clang/lib/Sema/SemaExprObjC.cpp
index ce80db7ca6e..ed780efd4cf 100644
--- a/clang/lib/Sema/SemaExprObjC.cpp
+++ b/clang/lib/Sema/SemaExprObjC.cpp
@@ -3161,7 +3161,7 @@ ExprResult Sema::BuildInstanceMessage(Expr *Receiver,
           Prop->getPropertyAttributes() & ObjCPropertyDecl::OBJC_PR_weak;
         if (!IsWeak && Sel.isUnarySelector())
           IsWeak = ReturnType.getObjCLifetime() & Qualifiers::OCL_Weak;
-        if (IsWeak &&
+        if (IsWeak && !isUnevaluatedContext() &&
             !Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, LBracLoc))
           getCurFunction()->recordUseOfWeak(Result, Prop);
       }