From bdc0fed2fc41f448437a78269fdb6c7999739c68 Mon Sep 17 00:00:00 2001
From: Christopher Maes <cmaes@nvidia.com>
Date: Mon, 12 May 2025 09:35:54 -0700
Subject: [PATCH] Fix issue with not halting on integer infeasible problems

This PR fixes an issues where cuOpt does not correctly stop, on a
problem that has been proven integer infeasible (but had a feasible
root relaxation).
---
 cpp/src/dual_simplex/branch_and_bound.cpp | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/cpp/src/dual_simplex/branch_and_bound.cpp b/cpp/src/dual_simplex/branch_and_bound.cpp
index 721b8ecda9..1b8a307d22 100644
--- a/cpp/src/dual_simplex/branch_and_bound.cpp
+++ b/cpp/src/dual_simplex/branch_and_bound.cpp
@@ -818,6 +818,14 @@ mip_status_t branch_and_bound_t<i_t, f_t>::solve(mip_solution_t<i_t, f_t>& solut
     }
   }
 
+  if (heap.size() == 0 && get_upper_bound<f_t>() == inf) {
+    settings.log.printf("Integer infeasible.\n");
+    status = mip_status_t::INFEASIBLE;
+    if (settings.heuristic_preemption_callback != nullptr) {
+      settings.heuristic_preemption_callback();
+    }
+  }
+
   uncrush_primal_solution(original_problem, original_lp, incumbent.x, solution.x);
   solution.objective          = incumbent.objective;
   solution.lower_bound        = lower_bound;