From 58aa5edb020e344484d0845eff456ff734143cec Mon Sep 17 00:00:00 2001
From: Gaetan Lepage <gaetan@glepage.com>
Date: Tue, 3 Mar 2026 23:37:41 +0000
Subject: [PATCH] python3Packages.pyamttings: fix cuda build

---
 .../python-modules/pymatting/default.nix          | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/pkgs/development/python-modules/pymatting/default.nix b/pkgs/development/python-modules/pymatting/default.nix
index f53b44996d1e..e74dbd1eb9fd 100644
--- a/pkgs/development/python-modules/pymatting/default.nix
+++ b/pkgs/development/python-modules/pymatting/default.nix
@@ -16,7 +16,9 @@
   pyopencl,
 
   # tests
+  pocl,
   pytestCheckHook,
+  writableTmpDirAsHomeHook,
 
   config,
   cudaSupport ? config.cudaSupport,
@@ -49,7 +51,16 @@ buildPythonPackage (finalAttrs: {
 
   pythonImportsCheck = [ "pymatting" ];
 
-  nativeCheckInputs = [ pytestCheckHook ];
+  nativeCheckInputs = [
+    pytestCheckHook
+  ]
+  ++ lib.optionals cudaSupport [
+    # Provides a CPU-based OpenCL ICD so that pyopencl's module-level
+    # cl.create_some_context() succeeds without GPU hardware.
+    pocl
+    # pocl needs a writable $HOME for its kernel cache directory.
+    writableTmpDirAsHomeHook
+  ];
 
   disabledTests = [
     # no access to input data set
@@ -61,7 +72,7 @@ buildPythonPackage (finalAttrs: {
   ];
 
   disabledTestPaths = lib.optionals cudaSupport [
-    # pyopencl._cl.LogicError: clGetPlatformIDs failed: PLATFORM_NOT_FOUND_KHR
+    # Requires a CUDA driver for cupy GPU operations
     "tests/test_foreground.py"
   ];