Avoid warnings from Unified Runtime Level Zero adapter

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 * Removed stale `select_host_device` and `has_host_device` names from `dpctl.__all__`, which made `from dpctl import *` fail with `AttributeError` [gh-2410](https://github.com/IntelPython/dpctl/pull/2410)
+* `dpctl.SyclPlatform.get_devices` no longer prints Unified Runtime warnings for `device_type="custom"` on non-OpenCL platforms, where custom devices are not supported [gh-2306](https://github.com/IntelPython/dpctl/pull/2306)
 
 ### Maintenance
 

dpctl/_sycl_platform.pyx

@@ -387,8 +387,10 @@ cdef class SyclPlatform(_SyclPlatform):
             device_type (str, :class:`dpctl.device_type`, optional):
                 A :class:`dpctl.device_type` enum value or a string that
                 specifies a SYCL device type. Currently, accepted values are:
-                "gpu", "cpu", "accelerator", or "all", and their equivalent
-                ``dpctl.device_type`` enumerators.
+                "gpu", "cpu", "accelerator", "automatic", "custom", or "all",
+                and their equivalent ``dpctl.device_type`` enumerators.
+                Only OpenCL platforms support custom devices; for other
+                platforms, "custom" returns an empty tuple.
                 Default: ``dpctl.device_type.all``.
 
         Returns:

dpctl/tests/test_sycl_platform.py

@@ -260,6 +260,24 @@ def test_platform_get_devices_enum_device_type():
                     assert (d.device_type == dty for d in devices)
 
 
+@pytest.mark.parametrize("dty", ["custom", device_type.custom])
+def test_platform_get_devices_custom_non_opencl(dty, capfd):
+    platforms = [
+        p
+        for p in dpctl.get_platforms()
+        if p.backend != dpctl.backend_type.opencl
+    ]
+    if not platforms:
+        pytest.skip("No non-OpenCL platforms available")
+    capfd.readouterr()
+    for p in platforms:
+        assert len(p.get_devices(device_type=dty)) == 0
+    out, err = capfd.readouterr()
+    # e.g., the Level Zero adapter warns on device_type::custom
+    assert out == ""
+    assert err == ""
+
+
 def test_platform_get_composite_devices():
     platforms = dpctl.get_platforms()
     if platforms:

libsyclinterface/include/syclinterface/dpctl_sycl_platform_interface.h

@@ -183,6 +183,9 @@ size_t DPCTLPlatform_Hash(__dpctl_keep const DPCTLSyclPlatformRef PRef);
  * @brief Returns a vector of devices associated with sycl::platform referenced
  * by DPCTLSyclPlatformRef object.
  *
+ * Only OpenCL platforms support custom devices; for other platforms,
+ * DPCTL_CUSTOM returns an empty vector.
+ *
  * @param    PRef           The DPCTLSyclPlatformRef pointer.
  * @param    DTy            A DPCTLSyclDeviceType enum value.
  * @return   A DPCTLDeviceVectorRef with devices associated with given PRef.

libsyclinterface/source/dpctl_sycl_platform_interface.cpp

@@ -304,6 +304,15 @@ DPCTLPlatform_GetDevices(__dpctl_keep const DPCTLSyclPlatformRef PRef,
         return wrap<vecTy>(DevicesVectorPtr);
     }
 
+    // Only OpenCL supports custom devices; other backends may warn when asked
+    // for them (e.g., the Unified Runtime Level Zero adapter)
+    if (DTy == DPCTLSyclDeviceType::DPCTL_CUSTOM &&
+        DPCTL_SyclBackendToDPCTLBackendType(P->get_backend()) !=
+            DPCTLSyclBackendType::DPCTL_OPENCL)
+    {
+        return wrap<vecTy>(DevicesVectorPtr);
+    }
+
     try {
         auto SyclDTy = DPCTL_DPCTLDeviceTypeToSyclDeviceType(DTy);
         auto Devices = P->get_devices(SyclDTy);