From 518a13cb41a064ae0bec34d7ae6b347db991369c Mon Sep 17 00:00:00 2001
From: Doug Torrance <dtorrance@piedmont.edu>
Date: Wed, 25 Sep 2024 11:19:45 -0400
Subject: [PATCH] Check that list is nonempty before calling factory function

Otherwise we get a segfault
---
 M2/Macaulay2/e/interface/factory.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/M2/Macaulay2/e/interface/factory.cpp b/M2/Macaulay2/e/interface/factory.cpp
index 957b2e59c03..7a827a7ee0a 100644
--- a/M2/Macaulay2/e/interface/factory.cpp
+++ b/M2/Macaulay2/e/interface/factory.cpp
@@ -785,6 +785,11 @@ M2_arrayintOrNull rawIdealReorder(const Matrix *M)
             }
         }
 
+      if (I.length() == 0) {
+        ERROR("expected at least one generator");
+        return nullptr;
+      }
+
       List<int> t = neworderint(I);
 
       int n = t.length();