From 6c71eb23eb5b70f6b513f3d8820feb22ba900096 Mon Sep 17 00:00:00 2001
From: jiqing-feng <jiqing.feng@intel.com>
Date: Wed, 16 Sep 2026 14:35:07 +0800
Subject: [PATCH] Fix `egg_info.writers` entry point module path (#829)
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With `kernels` installed, any setuptools source build in the same
environment fails, including builds of unrelated packages:

```
File "setuptools/command/egg_info.py", line 304, in run
    writer = ep.load()
ModuleNotFoundError: No module named 'kernels.lockfile'
```

Reproducer:

```bash
pip install kernels==0.17.0
printf 'from setuptools import setup\nsetup(name="smoke", version="0.1")\n' > setup.py
python setup.py egg_info
```

`kernels/pyproject.toml` registers a setuptools entry point pointing at
a module that is not shipped:

```toml
[project.entry-points."egg_info.writers"]
"kernels.lock" = "kernels.lockfile:write_egg_lockfile"
```

`write_egg_lockfile` lives in `kernels/locking.py`; there is no
`kernels/lockfile.py` in the wheel. The entry point was not updated when
`lockfile.py` was renamed to `locking.py`.

setuptools loads **all** registered `egg_info.writers` on every
`egg_info` run, so a broken writer from any installed distribution takes
down unrelated builds. PEP 517 isolated builds are unaffected;
`--no-build-isolation` builds reuse the ambient setuptools and always
hit it.

Present in 0.17.0 and on `main`; 0.16.2 is the last good release.

Point the entry point at `kernels.locking`, and add a regression test
that loads it the way setuptools does — nothing covered this path, which
is why the rename regressed silently.

Built a wheel from this branch and installed it:

- `ep.load()` resolves to the real function.
- The reproducer above succeeds.
- The new test passes, and fails when reverted to `kernels.lockfile`.
---
 kernels/pyproject.toml             |  2 +-
 kernels/tests/test_entry_points.py | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 kernels/tests/test_entry_points.py

diff --git a/kernels/pyproject.toml b/kernels/pyproject.toml
index fc946bc4..739c31ac 100644
--- a/kernels/pyproject.toml
+++ b/kernels/pyproject.toml
@@ -63,7 +63,7 @@ docs = [
 kernels = "kernels.cli:main"
 
 [project.entry-points."egg_info.writers"]
-"kernels.lock" = "kernels.lockfile:write_egg_lockfile"
+"kernels.lock" = "kernels.locking:write_egg_lockfile"
 
 [tool.maturin]
 module-name = "kernels._rust"
diff --git a/kernels/tests/test_entry_points.py b/kernels/tests/test_entry_points.py
new file mode 100644
index 00000000..553d4c37
--- /dev/null
+++ b/kernels/tests/test_entry_points.py
@@ -0,0 +1,19 @@
+from importlib.metadata import distribution
+
+import pytest
+
+
+def test_egg_info_writer_entry_point_is_importable():
+    """The `egg_info.writers` entry point is loaded by setuptools during *any*
+    `egg_info` run in an environment where `kernels` is installed, including
+    builds of unrelated packages. If it points at a module that is not shipped,
+    every such build fails with `ModuleNotFoundError`."""
+    entry_points = [ep for ep in distribution("kernels").entry_points if ep.group == "egg_info.writers"]
+    assert entry_points, "no egg_info.writers entry point registered"
+
+    for ep in entry_points:
+        try:
+            writer = ep.load()
+        except ModuleNotFoundError as e:
+            pytest.fail(f"entry point {ep.name} = {ep.value!r} is not importable: {e}")
+        assert callable(writer)