fixup! feat(core.utils): collapse empty ptxas_options sequence to None

Author: cpcloud

cuda_core/cuda/core/utils/_program_cache.py

@@ -244,12 +244,15 @@ def _gate_identity(v):
 def _gate_ptxas_options(v):
     # ``_prepare_nvjitlink_options`` emits one ``-Xptxas=<s>`` per element, and
     # treats ``str`` as a single-element sequence. Canonicalize to a tuple so
-    # ``"-v"`` / ``["-v"]`` / ``("-v",)`` all hash the same.
+    # ``"-v"`` / ``["-v"]`` / ``("-v",)`` all hash the same. An empty sequence
+    # emits no flags, so collapse it to ``None`` too.
     if v is None:
         return None
     if isinstance(v, str):
         return ("-Xptxas=" + v,)
     if isinstance(v, collections.abc.Sequence):
+        if len(v) == 0:
+            return None
         return tuple(f"-Xptxas={s}" for s in v)
     return v
 

cuda_core/tests/test_program_cache.py

@@ -401,6 +401,10 @@ def test_make_program_cache_key_ptx_driver_ignored_fields_collapse(field, a, b,
         pytest.param("-v", ["-v"], id="str_vs_list"),
         pytest.param("-v", ("-v",), id="str_vs_tuple"),
         pytest.param(["-v"], ("-v",), id="list_vs_tuple"),
+        # Empty sequence emits no -Xptxas flags; must match None.
+        pytest.param(None, [], id="none_vs_empty_list"),
+        pytest.param(None, (), id="none_vs_empty_tuple"),
+        pytest.param([], (), id="empty_list_vs_empty_tuple"),
     ],
 )
 def test_make_program_cache_key_ptx_ptxas_options_canonicalized(a, b, monkeypatch):