From 432771c690b5064cd834ddfb99b13edb282bf32d Mon Sep 17 00:00:00 2001
From: Phillip Cloud <417981+cpcloud@users.noreply.github.com>
Date: Tue, 21 Apr 2026 11:14:56 -0400
Subject: [PATCH 1/3] feat(core): convert Linker.backend from property to
 classmethod
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Allows querying the linking backend without constructing a Linker
instance — useful for dispatching on input format (PTX vs. LTOIR)
before linking.

Updates existing call sites (Program init, test_linker) to use the
new invocation form Linker.backend().
---
 cuda_core/cuda/core/_linker.pyx  | 20 ++++++++++++++++----
 cuda_core/cuda/core/_program.pyx |  2 +-
 cuda_core/tests/test_linker.py   |  2 +-
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/cuda_core/cuda/core/_linker.pyx b/cuda_core/cuda/core/_linker.pyx
index 09aa9863cd7..2a4bda413c2 100644
--- a/cuda_core/cuda/core/_linker.pyx
+++ b/cuda_core/cuda/core/_linker.pyx
@@ -167,10 +167,22 @@ cdef class Linker:
         else:
             return as_py(self._culink_handle)
 
-    @property
-    def backend(self) -> str:
-        """Return this Linker instance's underlying backend."""
-        return "nvJitLink" if self._use_nvjitlink else "driver"
+    @classmethod
+    def backend(cls) -> str:
+        """Return which linking backend will be used.
+
+        Returns ``"nvJitLink"`` when the nvJitLink library is available
+        and meets the minimum version requirement, otherwise ``"driver"``.
+
+        .. note::
+
+            Prefer letting :class:`Linker` decide. Query ``backend()``
+            only when you need to dispatch based on input format (for
+            example: choose PTX vs. LTOIR before constructing a
+            ``Linker``). The returned string names an implementation
+            detail whose support matrix may shift across CTK releases.
+        """
+        return "driver" if _decide_nvjitlink_or_driver() else "nvJitLink"
 
 
 # =============================================================================
diff --git a/cuda_core/cuda/core/_program.pyx b/cuda_core/cuda/core/_program.pyx
index 194ef6da53f..bcbd8ca3758 100644
--- a/cuda_core/cuda/core/_program.pyx
+++ b/cuda_core/cuda/core/_program.pyx
@@ -649,7 +649,7 @@ cdef inline int Program_init(Program self, object code, str code_type, object op
         self._linker = Linker(
             ObjectCode._init(code.encode(), code_type), options=_translate_program_options(options)
         )
-        self._backend = self._linker.backend
+        self._backend = self._linker.backend()
 
     elif code_type == "nvvm":
         _get_nvvm_module()  # Validate NVVM availability
diff --git a/cuda_core/tests/test_linker.py b/cuda_core/tests/test_linker.py
index 0d4ff91dcd9..863a55af713 100644
--- a/cuda_core/tests/test_linker.py
+++ b/cuda_core/tests/test_linker.py
@@ -92,7 +92,7 @@ def test_linker_init(compile_ptx_functions, options):
     linker = Linker(*compile_ptx_functions, options=options)
     object_code = linker.link("cubin")
     assert isinstance(object_code, ObjectCode)
-    assert linker.backend == ("driver" if is_culink_backend else "nvJitLink")
+    assert linker.backend() == ("driver" if is_culink_backend else "nvJitLink")
 
 
 def test_linker_init_invalid_arch(compile_ptx_functions):

From 6327b220dad9a1aa97b272ae2566df70c6692ef0 Mon Sep 17 00:00:00 2001
From: Phillip Cloud <417981+cpcloud@users.noreply.github.com>
Date: Tue, 21 Apr 2026 11:15:22 -0400
Subject: [PATCH 2/3] test(core): add tests for Linker.backend classmethod

Covers classmethod invocation (Linker.backend() without an instance),
memoisation flag handling, probe-on-first-use, and non-property
attribute semantics.
---
 cuda_core/tests/test_linker.py | 39 ++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/cuda_core/tests/test_linker.py b/cuda_core/tests/test_linker.py
index 863a55af713..9b3d33e891f 100644
--- a/cuda_core/tests/test_linker.py
+++ b/cuda_core/tests/test_linker.py
@@ -2,6 +2,8 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
+import inspect
+
 import pytest
 
 from cuda.core import Device, Linker, LinkerOptions, Program, ProgramOptions, _linker
@@ -242,3 +244,40 @@ def test_linker_options_nvjitlink_options_as_str():
     assert f"-arch={ARCH}" in options
     assert "-g" in options
     assert "-lineinfo" in options
+
+
+class TestBackendClassmethod:
+    def test_backend_returns_nvjitlink(self, monkeypatch):
+        monkeypatch.setattr(_linker, "_use_nvjitlink_backend", True)
+        assert Linker.backend() == "nvJitLink"
+
+    def test_backend_returns_driver(self, monkeypatch):
+        monkeypatch.setattr(_linker, "_use_nvjitlink_backend", False)
+        assert Linker.backend() == "driver"
+
+    def test_backend_invokes_probe_when_not_memoised(self, monkeypatch):
+        monkeypatch.setattr(_linker, "_use_nvjitlink_backend", None)
+        called = []
+
+        def fake_decide():
+            called.append(True)
+            return False  # False = not falling back to driver = nvJitLink
+
+        monkeypatch.setattr(_linker, "_decide_nvjitlink_or_driver", fake_decide)
+        result = Linker.backend()
+        assert result == "nvJitLink"
+        assert called, "_decide_nvjitlink_or_driver was not called"
+
+    def test_backend_is_classmethod(self):
+        attr = inspect.getattr_static(Linker, "backend")
+        assert isinstance(attr, classmethod)
+
+    def test_backend_is_not_property(self):
+        """backend is a classmethod, not a property.
+
+        This is an intentional breaking change from the prior property API.
+        Attribute-style access (``linker.backend``) now returns a bound method,
+        not a string. All call sites must use parens: ``Linker.backend()``.
+        """
+        attr = inspect.getattr_static(Linker, "backend")
+        assert not isinstance(attr, property)

From 12d291b1693a3db25bb6662f60c628364b3ca8e9 Mon Sep 17 00:00:00 2001
From: Phillip Cloud <417981+cpcloud@users.noreply.github.com>
Date: Tue, 21 Apr 2026 11:15:23 -0400
Subject: [PATCH 3/3] docs(core): add 1.0.0 release notes for Linker.backend
 change

Breaking change: Linker.backend is now a classmethod, so call sites
must use parens: Linker.backend().
---
 cuda_core/docs/source/release/1.0.0-notes.rst | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 cuda_core/docs/source/release/1.0.0-notes.rst

diff --git a/cuda_core/docs/source/release/1.0.0-notes.rst b/cuda_core/docs/source/release/1.0.0-notes.rst
new file mode 100644
index 00000000000..d289500deff
--- /dev/null
+++ b/cuda_core/docs/source/release/1.0.0-notes.rst
@@ -0,0 +1,17 @@
+.. SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+.. SPDX-License-Identifier: Apache-2.0
+
+.. currentmodule:: cuda.core
+
+``cuda.core`` 1.0.0 Release Notes
+=================================
+
+
+Breaking Changes
+----------------
+
+- :meth:`Linker.backend` is now a classmethod instead of an instance property.
+  Call sites must use ``Linker.backend()`` (with parentheses) instead of
+  ``linker.backend``. This allows querying the linking backend without
+  constructing a ``Linker`` instance — for example, to choose between PTX and
+  LTOIR input before linking.