python3Packages.rembg: fix cuda build

Author: GaetanLepage

pkgs/development/python-modules/rembg/default.nix

@@ -33,8 +33,12 @@
 
   # tests
   versionCheckHook,
+  pocl,
 
   withCli ? false,
+  config,
+  cudaSupport ? config.cudaSupport,
+  writableTmpDirAsHomeHook,
 }:
 
 let
@@ -100,9 +104,17 @@ buildPythonPackage (finalAttrs: {
   postInstall = lib.optionalString (!withCli) "rm -r $out/bin";
 
   # not running python tests, as they require network access
-  nativeCheckInputs = lib.optionals withCli [
-    versionCheckHook
-  ];
+  nativeCheckInputs =
+    lib.optionals withCli [
+      versionCheckHook
+    ]
+    ++ 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
+    ];
   versionCheckKeepEnvironment = [
     # Otherwise, fail with:
     # RuntimeError: cannot cache function '_make_tree': no locator available for file