Merge pull request #25291 from xedin/refactor-open-generic

[ConstraintSystem] Refactor openGeneric/openFunctionType

lib/Sema/CSSimplify.cpp

@@ -4885,10 +4885,8 @@ ConstraintSystem::simplifyOpaqueUnderlyingTypeConstraint(Type type1, Type type2,
   // corresponding to the underlying type should be the constraints on the
   // underlying return type.
   OpenedTypeMap replacements;
-  openGeneric(nullptr, DC, opaque2->getBoundSignature(),
-              /*skip self*/ false,
-              locator, replacements);
-  
+  openGeneric(DC, opaque2->getBoundSignature(), locator, replacements);
+
   auto underlyingTyVar = openType(opaque2->getInterfaceType(),
                                   replacements);
   assert(underlyingTyVar);