fix(cuda.core): reject double-dashed NVVM options at the source

Add a guard at the single exit point of _prepare_nvvm_options_impl that
raises if any option is double-dashed. libNVVM accepts only single-dashed
options, and every option on this path is generated from typed fields, so
a double dash can only mean a bug in cuda.core rather than bad user input.
Raising here names the offending option instead of leaving the user with
libNVVM's opaque NVVM_ERROR_INVALID_OPTION.

The guard is a separate cpdef helper so a test can exercise it directly;
an inline check would be unreachable and therefore unverifiable. A second
test sets every NVVM-supported field of ProgramOptions and asserts no
emitted option is double-dashed, so the invariant covers options added
later.

Verified by mutation: restoring --numba-debug turns three tests red, and
the compile test then fails with this guard's error rather than libNVVM's.

The NVRTC path keeps --numba-debug, which it accepts; the guard is scoped
to the NVVM emitter.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: rparolin

cuda_core/cuda/core/_program.pyi

@@ -429,6 +429,17 @@ _nvvm_import_attempted = False
 def _can_load_generated_ptx() -> bool:
     """Check if the driver can load PTX generated by the current NVRTC version."""
 
+def _assert_single_dashed_nvvm_options(options: list[str]) -> None:
+    """Guard against emitting a double-dashed option to libNVVM.
+
+    libNVVM's parser accepts only single-dashed options and rejects the
+    double-dashed spelling of every option with NVVM_ERROR_INVALID_OPTION
+    (see #2570). Every option on this path is generated from typed fields, so
+    a double dash can only mean a bug in ``cuda.core`` rather than bad user
+    input. Fail here, naming the option, instead of leaving the user with
+    libNVVM's opaque error.
+    """
+
 def _program_compile_uncached(program, target_type, name_expressions, logs):
     """Run ``Program_compile`` without the cache wrapper.
 

cuda_core/cuda/core/_program.pyx

@@ -1225,6 +1225,24 @@ cdef inline list _prepare_nvrtc_options_impl(object opts):
     return [o.encode() for o in options]
 
 
+cpdef void _assert_single_dashed_nvvm_options(options: list[str]) except *:
+    """Guard against emitting a double-dashed option to libNVVM.
+
+    libNVVM's parser accepts only single-dashed options and rejects the
+    double-dashed spelling of every option with NVVM_ERROR_INVALID_OPTION
+    (see #2570). Every option on this path is generated from typed fields, so
+    a double dash can only mean a bug in ``cuda.core`` rather than bad user
+    input. Fail here, naming the option, instead of leaving the user with
+    libNVVM's opaque error.
+    """
+    for option in options:
+        if option.startswith("--"):
+            raise RuntimeError(
+                f"Internal error: NVVM option {option!r} is double-dashed. libNVVM accepts "
+                f"only single-dashed options; emit {option[1:]!r} instead."
+            )
+
+
 cdef inline object _prepare_nvvm_options_impl(object opts, bint as_bytes):
     """Build NVVM-specific compiler options."""
     options = []
@@ -1320,6 +1338,8 @@ cdef inline object _prepare_nvvm_options_impl(object opts, bint as_bytes):
     if unsupported:
         raise CUDAError(f"The following options are not supported by NVVM backend: {', '.join(unsupported)}")
 
+    _assert_single_dashed_nvvm_options(options)
+
     if as_bytes:
         return [o.encode() for o in options]
     else:

cuda_core/tests/test_program.py

@@ -775,6 +775,40 @@ def test_nvvm_program_options_as_bytes_numba_debug():
     assert b"-g" in nvvm_bytes
 
 
+@pytest.mark.agent_authored(model="claude-opus-5[1m]")
+def test_nvvm_options_reject_double_dash():
+    """The guard must name a double-dashed option rather than let libNVVM
+    reject it with an opaque error (see #2570)."""
+    from cuda.core._program import _assert_single_dashed_nvvm_options
+
+    _assert_single_dashed_nvvm_options(["-arch=compute_80", "-g", "-numba-debug"])
+
+    with pytest.raises(RuntimeError, match=r"--numba-debug.*double-dashed"):
+        _assert_single_dashed_nvvm_options(["-arch=compute_80", "--numba-debug"])
+
+
+@nvvm_available
+@pytest.mark.agent_authored(model="claude-opus-5[1m]")
+def test_nvvm_program_options_as_bytes_all_single_dashed():
+    """Every option cuda.core emits to libNVVM must be single-dashed, because
+    libNVVM rejects the double-dashed spelling of all of them (see #2570).
+    This covers every NVVM-supported field of ProgramOptions."""
+    options = ProgramOptions(
+        arch="sm_80",
+        debug=True,
+        numba_debug=True,
+        device_code_optimize=True,
+        ftz=True,
+        prec_sqrt=True,
+        prec_div=True,
+        fma=True,
+    )
+    nvvm_bytes = options.as_bytes("nvvm")
+    assert nvvm_bytes, "expected at least one emitted option"
+    offenders = [o for o in nvvm_bytes if o.startswith(b"--")]
+    assert not offenders, f"double-dashed options are rejected by libNVVM: {offenders}"
+
+
 @nvvm_available
 @pytest.mark.skipif(
     not _check_nvvm_supports_numba_debug(),