Update ASTMangler.cpp

Author: Azoy

lib/AST/ASTMangler.cpp

@@ -1619,11 +1619,13 @@ void ASTMangler::appendType(Type type, GenericSignature sig,
           appendSymbolicExtendedExistentialType(referent, EMT, sig, forDecl);
           return;
         }
+      }
 
+      if (EMT->getInstanceType()->isExistentialType() &&
+          EMT->getExistentialLayout().needsExtendedShape(AllowInverses))
         appendConstrainedExistential(EMT->getInstanceType(), sig, forDecl);
-      } else {
+      else
         appendType(EMT->getInstanceType(), sig, forDecl);
-      }
 
       if (EMT->hasRepresentation()) {
         appendOperator("Xm",