Deprecate unused dpnp.config settings

CHANGELOG.md

@@ -64,6 +64,7 @@ This release is compatible with NumPy 2.5.
 ### Deprecated
 
 * Deprecated setting the shape via the `shape` attribute of `dpnp.ndarray` and `dpnp.tensor.usm_ndarray`. Use `dpnp.reshape`/`dpnp.tensor.reshape` (or the `reshape` method) instead [#2967](https://github.com/IntelPython/dpnp/pull/2967)
+* Deprecated `dpnp.config.__DPNP_QUEUE_GPU__`, `dpnp.config.__DPNP_OUTPUT_NUMPY__` and `dpnp.config.__DPNP_OUTPUT_DPCTL_DEFAULT_SHARED__`, which have no effect; reading or setting them now emits a `DeprecationWarning` [#3107](https://github.com/IntelPython/dpnp/pull/3107)
 
 ### Removed
 

dpnp/config.py

@@ -28,32 +28,62 @@
 
 
 import os
+import sys
+import types
+import warnings
 
 __DPNP_ORIGIN__ = int(os.getenv("DPNP_ORIGIN", 0))
 """
 Explicitly use original host Python NumPy
 """
 
-__DPNP_QUEUE_GPU__ = int(os.getenv("DPNP_QUEUE_GPU", 0))
-"""
-Explicitly use GPU for SYCL queue
-"""
-
-__DPNP_OUTPUT_NUMPY__ = int(os.getenv("DPNP_OUTPUT_NUMPY", 0))
-"""
-Explicitly use NumPy.ndarray as return type for creation functions
-"""
-
-__DPNP_OUTPUT_DPCTL_DEFAULT_SHARED__ = int(
-    os.getenv("DPNP_OUTPUT_DPCTL_DEFAULT_SHARED", 0)
-)
-"""
-Explicitly use SYCL shared memory parameter in DPCtl array constructor for creation functions
-"""
-
 __DPNP_RAISE_EXCEPION_ON_NUMPY_FALLBACK__ = int(
     os.getenv("DPNP_RAISE_EXCEPION_ON_NUMPY_FALLBACK", 1)
 )
 """
 Trigger non-implemented exception when DPNP fallbacks on NumPy implementation
 """
+
+# settings that no longer have any effect: attribute name -> env var name
+_DEPRECATED_SETTINGS = {
+    "__DPNP_QUEUE_GPU__": "DPNP_QUEUE_GPU",
+    "__DPNP_OUTPUT_NUMPY__": "DPNP_OUTPUT_NUMPY",
+    "__DPNP_OUTPUT_DPCTL_DEFAULT_SHARED__": "DPNP_OUTPUT_DPCTL_DEFAULT_SHARED",
+}
+
+# values assigned to deprecated settings after import
+_deprecated_values = {}
+
+
+def _warn_deprecated(name):
+    warnings.warn(
+        f"`dpnp.config.{name}` is deprecated, and will be removed in a "
+        "future release. It has no effect.",
+        DeprecationWarning,
+        stacklevel=3,
+    )
+
+
+def __getattr__(name):
+    if name in _DEPRECATED_SETTINGS:
+        _warn_deprecated(name)
+        if name in _deprecated_values:
+            return _deprecated_values[name]
+        # parse lazily, so a bad env value can't break `import dpnp`
+        return int(os.getenv(_DEPRECATED_SETTINGS[name], 0))
+    raise AttributeError(f"module {__name__!r} has no attribute {name!r}")
+
+
+class _ConfigModule(types.ModuleType):
+    """Warn also on assignment to a deprecated setting."""
+
+    def __setattr__(self, name, value):
+        if name in _DEPRECATED_SETTINGS:
+            _warn_deprecated(name)
+            # keep it out of the module dict, so reads still warn
+            _deprecated_values[name] = value
+        else:
+            super().__setattr__(name, value)
+
+
+sys.modules[__name__].__class__ = _ConfigModule

dpnp/tests/test_config.py

@@ -0,0 +1,62 @@
+import re
+import warnings
+
+import pytest
+
+import dpnp
+
+
+@pytest.fixture(autouse=True)
+def reset_deprecated_values(monkeypatch):
+    # drop values assigned by other tests
+    monkeypatch.setattr(dpnp.config, "_deprecated_values", {})
+
+
+class TestDeprecatedSettings:
+    @pytest.mark.parametrize(
+        "name, env",
+        [
+            ("__DPNP_QUEUE_GPU__", "DPNP_QUEUE_GPU"),
+            ("__DPNP_OUTPUT_NUMPY__", "DPNP_OUTPUT_NUMPY"),
+            (
+                "__DPNP_OUTPUT_DPCTL_DEFAULT_SHARED__",
+                "DPNP_OUTPUT_DPCTL_DEFAULT_SHARED",
+            ),
+        ],
+    )
+    def test_read_warns(self, monkeypatch, name, env):
+        monkeypatch.delenv(env, raising=False)
+        with pytest.warns(DeprecationWarning, match=re.escape(name)):
+            value = getattr(dpnp.config, name)
+        assert value == 0
+
+    @pytest.mark.parametrize(
+        "name",
+        [
+            "__DPNP_QUEUE_GPU__",
+            "__DPNP_OUTPUT_NUMPY__",
+            "__DPNP_OUTPUT_DPCTL_DEFAULT_SHARED__",
+        ],
+    )
+    def test_write_warns(self, name):
+        with pytest.warns(DeprecationWarning, match=re.escape(name)):
+            setattr(dpnp.config, name, 1)
+
+        # a later read must still warn
+        with pytest.warns(DeprecationWarning, match=re.escape(name)):
+            value = getattr(dpnp.config, name)
+        assert value == 1
+
+    @pytest.mark.parametrize(
+        "name",
+        ["__DPNP_ORIGIN__", "__DPNP_RAISE_EXCEPION_ON_NUMPY_FALLBACK__"],
+    )
+    def test_no_warning(self, monkeypatch, name):
+        with warnings.catch_warnings():
+            warnings.simplefilter("error")
+            value = getattr(dpnp.config, name)
+            monkeypatch.setattr(dpnp.config, name, value)
+
+    def test_unknown_name(self):
+        with pytest.raises(AttributeError, match="has no attribute"):
+            getattr(dpnp.config, "__DPNP_UNKNOWN__")