1 files changed, 4 insertions, 0 deletions
diff --git a/lib/Sema/SemaTemplateDeduction.cpp b/lib/Sema/SemaTemplateDeduction.cpp
index 762e51a32c..add8e10831 100644
--- a/lib/Sema/SemaTemplateDeduction.cpp
+++ b/lib/Sema/SemaTemplateDeduction.cpp
@@ -977,6 +977,10 @@ DeduceTemplateArguments(Sema &S,
   //     cv-list T
   if (const TemplateTypeParmType *TemplateTypeParm
         = Param->getAs<TemplateTypeParmType>()) {
+    // Just skip any attempts to deduce from a placeholder type.
+    if (Arg->isPlaceholderType())
+      return Sema::TDK_Success;
+    
     unsigned Index = TemplateTypeParm->getIndex();
     bool RecanonicalizeArg = false;