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juenglinjuenglin
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build(bindings): force rebuild on toolchain change via .build-toolchain stamp
cuda.bindings had no build-ext stamp at all and never forced rebuilds. Add a minimal toolchain-only stamp mirroring cuda.core's CUDA-major stamp pattern: _check_build_toolchain() sets force_build_ext when the toolchain changed since the last successful build; record_build_toolchain() writes the stamp after build_ext succeeds. setup.py reads force_build_ext in build_extensions and calls record_build_toolchain after a successful build. The cythonize build_dir is left flat (build/cython) -- the .pyx->.cpp step is toolchain-independent, so keying it would only force regenerating identical sources. Only the compiled .so is at risk, and force_build_ext fixes that. Addresses rwgk's P1 #1 (toolchain changes silently reuse binaries from the previous toolchain) for cuda.bindings: a gnu build followed by llvm in the same checkout now recompiles.
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‎cuda_bindings/build_hooks.py‎

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@@ -207,6 +207,54 @@ def _resolve_toolchain(debug=False, compile_for_coverage=False):
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return name, cc, cxx, extra_compile_args, extra_link_args
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# -----------------------------------------------------------------------
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# Toolchain stamp
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_BUILD_DIR = Path(__file__).parent / "build"
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# Records the toolchain of the last completed build, so setup.py can force
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# build_ext when it changes. Written by record_build_toolchain().
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_BUILD_TOOLCHAIN_STAMP = _BUILD_DIR / ".build-toolchain"
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force_build_ext = False
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# Set by _check_build_toolchain; read by record_build_toolchain.
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_last_toolchain = None
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def _check_build_toolchain(toolchain):
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"""Set force_build_ext when the toolchain changed since the last build.
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Setuptools' freshness check does not include the extension flags, so a
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stale .so compiled by a previous toolchain would otherwise be packaged.
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"""
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global force_build_ext, _last_toolchain
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_last_toolchain = toolchain
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try:
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previous = _BUILD_TOOLCHAIN_STAMP.read_text(encoding="utf-8").strip()
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except FileNotFoundError:
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previous = None
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# A missing stamp means the last build's toolchain is unknown, so force too.
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# On a first build that costs nothing: there are no artifacts to reuse.
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if previous != toolchain:
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print(f"Toolchain of last build: {previous} (building {toolchain}); forcing a full rebuild")
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force_build_ext = True
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def record_build_toolchain() -> None:
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"""Stamp the toolchain of the build that just completed.
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setup.py calls this after build_ext succeeds, so that a build which failed
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partway through does not claim outputs it never produced.
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"""
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global _last_toolchain
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if _last_toolchain is None:
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return # build never reached _check_build_toolchain (e.g. metadata-only)
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_BUILD_TOOLCHAIN_STAMP.parent.mkdir(parents=True, exist_ok=True)
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_BUILD_TOOLCHAIN_STAMP.write_text(_last_toolchain + "\n", encoding="utf-8")
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# -----------------------------------------------------------------------
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# Extension preparation helpers
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@@ -349,6 +397,10 @@ def get_static_libraries(f):
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if compile_for_coverage:
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cython_directives["linetrace"] = True
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# Force a full rebuild when the toolchain changed since the last successful
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# build, so a stale .so from a previous toolchain is never packaged.
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_check_build_toolchain(toolchain)
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_extensions = cythonize(
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extensions,
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nthreads=nthreads,

‎cuda_bindings/setup.py‎

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@@ -27,7 +27,12 @@ class build_ext(_build_ext):
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def build_extensions(self):
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if nthreads > 0:
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self.parallel = nthreads
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# A stale .so from a previous toolchain looks perfectly fresh;
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# see build_hooks._check_build_toolchain().
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if build_hooks.force_build_ext:
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self.force = True
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super().build_extensions()
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build_hooks.record_build_toolchain()
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class build_py(_build_py):

‎cuda_bindings/tests/test_build_hooks.py‎

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@@ -135,3 +135,52 @@ def fake_which(name):
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def test_llvm_present_passes(self, monkeypatch):
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monkeypatch.setattr(build_hooks.shutil, "which", lambda name: "/bin/" + name)
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build_hooks._check_toolchain_available("llvm")
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@pytest.fixture
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def stamp(tmp_path, monkeypatch):
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"""Redirect the toolchain stamp to a scratch path."""
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scratch = tmp_path / "build" / ".build-toolchain"
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monkeypatch.setattr(build_hooks, "_BUILD_TOOLCHAIN_STAMP", scratch)
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monkeypatch.setattr(build_hooks, "force_build_ext", False)
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monkeypatch.setattr(build_hooks, "_last_toolchain", None)
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monkeypatch.delenv("CUDA_PYTHON_TOOLCHAIN", raising=False)
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return scratch
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def _write_stamp(stamp, toolchain):
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stamp.parent.mkdir(parents=True, exist_ok=True)
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stamp.write_text(toolchain + "\n")
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class TestBuildToolchainStamp:
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"""Tests for _check_build_toolchain() and record_build_toolchain()."""
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@pytest.mark.agent_authored(model="glm-5.2")
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def test_missing_stamp_forces_rebuild(self, stamp):
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assert build_hooks._check_build_toolchain("gnu") is None
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assert build_hooks.force_build_ext is True
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@pytest.mark.agent_authored(model="glm-5.2")
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def test_same_toolchain_does_not_force(self, stamp):
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_write_stamp(stamp, "gnu")
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build_hooks._check_build_toolchain("gnu")
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assert build_hooks.force_build_ext is False
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@pytest.mark.agent_authored(model="glm-5.2")
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def test_changed_toolchain_forces_rebuild(self, stamp):
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_write_stamp(stamp, "gnu")
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build_hooks._check_build_toolchain("llvm")
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assert build_hooks.force_build_ext is True
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@pytest.mark.agent_authored(model="glm-5.2")
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def test_record_writes_stamp(self, stamp):
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build_hooks._check_build_toolchain("gnu")
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build_hooks.record_build_toolchain()
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assert stamp.read_text().strip() == "gnu"
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@pytest.mark.agent_authored(model="glm-5.2")
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def test_record_without_check_is_noop(self, stamp, monkeypatch):
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monkeypatch.setattr(build_hooks, "_last_toolchain", None)
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build_hooks.record_build_toolchain()
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assert not stamp.exists()

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