From d21b147fe0a0f23f4a7196a46417bf425e4e7935 Mon Sep 17 00:00:00 2001
From: Trevor McKay <tmgithub1@gmail.com>
Date: Thu, 26 Feb 2026 12:17:02 -0500
Subject: [PATCH] fix lifetime bug with presolve result

---
 .../optimization_problem.hpp                  |  2 ++
 cpp/src/pdlp/solve.cu                         | 20 +++++++++++--------
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/cpp/include/cuopt/linear_programming/optimization_problem.hpp b/cpp/include/cuopt/linear_programming/optimization_problem.hpp
index d0731f3aa9..92ca17216e 100644
--- a/cpp/include/cuopt/linear_programming/optimization_problem.hpp
+++ b/cpp/include/cuopt/linear_programming/optimization_problem.hpp
@@ -104,6 +104,8 @@ class optimization_problem_t {
 
   optimization_problem_t(raft::handle_t const* handle_ptr);
   optimization_problem_t(const optimization_problem_t<i_t, f_t>& other);
+  optimization_problem_t(optimization_problem_t<i_t, f_t>&&)            = default;
+  optimization_problem_t& operator=(optimization_problem_t<i_t, f_t>&&) = default;
 
   /**
    * @brief Check if this optimization problem is equivalent to another.
diff --git a/cpp/src/pdlp/solve.cu b/cpp/src/pdlp/solve.cu
index 9d4ab483fb..460ddc3921 100644
--- a/cpp/src/pdlp/solve.cu
+++ b/cpp/src/pdlp/solve.cu
@@ -1201,6 +1201,10 @@ optimization_problem_solution_t<i_t, f_t> solve_lp(
       CUOPT_LOG_INFO("Third-party presolve is disabled, skipping");
     }
 
+    // Declare result at outer scope so that result->reduced_problem (which may be
+    // referenced by problem.original_problem_ptr) remains alive through the solve.
+    std::optional<detail::third_party_presolve_result_t<i_t, f_t>> result;
+
     if (run_presolve) {
       detail::sort_csr(op_problem);
       // allocate no more than 10% of the time limit to presolve.
@@ -1208,14 +1212,14 @@ optimization_problem_solution_t<i_t, f_t> solve_lp(
       // But no less than 1 second, to avoid early timeout triggering known crashes
       const double presolve_time_limit =
         std::max(1.0, std::min(0.1 * lp_timer.remaining_time(), 60.0));
-      presolver   = std::make_unique<detail::third_party_presolve_t<i_t, f_t>>();
-      auto result = presolver->apply(op_problem,
-                                     cuopt::linear_programming::problem_category_t::LP,
-                                     settings.presolver,
-                                     settings.dual_postsolve,
-                                     settings.tolerances.absolute_primal_tolerance,
-                                     settings.tolerances.relative_primal_tolerance,
-                                     presolve_time_limit);
+      presolver = std::make_unique<detail::third_party_presolve_t<i_t, f_t>>();
+      result    = presolver->apply(op_problem,
+                                cuopt::linear_programming::problem_category_t::LP,
+                                settings.presolver,
+                                settings.dual_postsolve,
+                                settings.tolerances.absolute_primal_tolerance,
+                                settings.tolerances.relative_primal_tolerance,
+                                presolve_time_limit);
       if (!result.has_value()) {
         return optimization_problem_solution_t<i_t, f_t>(
           pdlp_termination_status_t::PrimalInfeasible, op_problem.get_handle_ptr()->get_stream());