[Sema] Resolve placeholder types before type deduction to silence

spurious `-Warc-repeated-use-of-weak` warnings

The spurious -Warc-repeated-use-of-weak warnings are issued when an
initializer expression uses a weak ObjC pointer.

My first attempt to silence the warnings (r350917) caused clang to
reject code that is legal in C++17. The patch is based on the feedback I
received from Richard when the patch was reverted.

http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20190422/268945.html
http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20190422/268943.html

Differential Revision: https://reviews.llvm.org/D62645

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@365382 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 466d9fdb9b..f44235491d 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -6678,6 +6678,14 @@ Sema::MaybeConvertParenListExprToParenExpr(Scope *S, Expr *OrigExpr) {
 ExprResult Sema::ActOnParenListExpr(SourceLocation L,
                                     SourceLocation R,
                                     MultiExprArg Val) {
+  for (size_t I = 0, E = Val.size(); I != E; ++I)
+    if (Val[I]->hasNonOverloadPlaceholderType()) {
+      ExprResult Result = CheckPlaceholderExpr(Val[I]);
+      if (!Result.isUsable())
+        return ExprError();
+      Val[I] = Result.get();
+    }
+
   return ParenListExpr::Create(Context, L, Val, R);
 }