Sema: Don't construct TupleType with InOutType inside

Author: slavapestov

lib/Sema/CSSimplify.cpp

@@ -7308,8 +7308,11 @@ ConstraintSystem::matchTypes(Type type1, Type type2, ConstraintKind kind,
   // would be handled by existental promotion in cases where it's allowed.
   if (isTupleWithUnresolvedPackExpansion(origType1) ||
       isTupleWithUnresolvedPackExpansion(origType2)) {
-    if (desugar1->is<TupleType>() != desugar2->is<TupleType>() &&
-        (!desugar1->isAny() && !desugar2->isAny())) {
+    if (isa<TupleType>(desugar1) != isa<TupleType>(desugar2) &&
+        !isa<InOutType>(desugar1) &&
+        !isa<InOutType>(desugar2) &&
+        !desugar1->isAny() &&
+        !desugar2->isAny()) {
       return matchTypes(
           desugar1->is<TupleType>() ? type1
                                     : TupleType::get({type1}, getASTContext()),