diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 45ce118..c826b83 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -8294,6 +8294,8 @@
         QualType Adjusted = Function->getType();
         if (!hasExplicitCallingConv(Adjusted))
           Adjusted = adjustCCAndNoReturn(Adjusted, Method->getType());
+        // This doesn't handle deduced return types, but both function
+        // declarations should be undeduced at this point.
         if (Context.hasSameType(Adjusted, Method->getType())) {
           FoundInstantiation = *I;
           Instantiation = Method;