[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, 4 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index eddf90178bc..f65e97ed0b7 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -14557,6 +14557,10 @@ void Sema::DiscardCleanupsInEvaluationContext() {
 }
 
 ExprResult Sema::HandleExprEvaluationContextForTypeof(Expr *E) {
+  ExprResult Result = CheckPlaceholderExpr(E);
+  if (Result.isInvalid())
+    return ExprError();
+  E = Result.get();
   if (!E->getType()->isVariablyModifiedType())
     return E;
   return TransformToPotentiallyEvaluated(E);