From 2ca07f26094c2b5b1b6a0a8f139b6fae15a2ab86 Mon Sep 17 00:00:00 2001
From: Max Buckley <maxwbuckley@gmail.com>
Date: Thu, 23 Jul 2026 10:46:57 +0200
Subject: [PATCH] fix(build): use rmm's device_uvector declaration, not a
 hand-rolled forward decl

As of rmm 26.10, rmm::device_uvector is defined inside the ABI inline namespace
rmm::RMM_ABI_NAMESPACE (rmm/detail/export.hpp). cuOpt's manual
  namespace rmm { template <typename T> class device_uvector; }
forward declaration in problem_checking.cuh injects a *second*, distinct
rmm::device_uvector into the plain rmm namespace, so every use becomes ambiguous
('rmm::device_uvector is ambiguous'), which fails the build against rmm 26.10.

Replace the hand-rolled forward declaration with #include <rmm/device_uvector.hpp>
so the correctly ABI-namespaced declaration is used. (cuOpt already disables the
analogous thrust/cub ABI namespaces via -DTHRUST_DISABLE_ABI_NAMESPACE /
-DCUB_DISABLE_NAMESPACE_MAGIC; rmm's ABI namespace is newer and has no such opt-out.)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Max Buckley <maxwbuckley@gmail.com>
---
 cpp/src/pdlp/utilities/problem_checking.cuh | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/cpp/src/pdlp/utilities/problem_checking.cuh b/cpp/src/pdlp/utilities/problem_checking.cuh
index 217080356c..5dc74808a2 100644
--- a/cpp/src/pdlp/utilities/problem_checking.cuh
+++ b/cpp/src/pdlp/utilities/problem_checking.cuh
@@ -10,10 +10,7 @@
 #include <cuopt/mathematical_optimization/optimization_problem.hpp>
 #include <cuopt/mathematical_optimization/pdlp/solver_settings.hpp>
 
-namespace rmm {
-template <typename T>
-class device_uvector;
-}  // namespace rmm
+#include <rmm/device_uvector.hpp>
 
 namespace cuopt::mathematical_optimization {