_unused_ is used for 'self' wherever the function does not use self.
assert(!args) is added in the places where METH_NOARGS is used.
assert(self) is added in a few places where self _is_ used.

In C, a narrow type is automatically extended, so those verbose suffixes
are not needed for anything.

@behrmann behrmann left a comment

...stration
Drop specification of kwargs in the _reader.Journal.add_match registration. The
handling was never implemented, so any any kwargs would be summarilly ignored.
The handling of kwargs is done in the python wrapper, so no kwargs are passed
to the native C function (and would be ignored if they were). IIRC, the plan
was initially to do this in the C extension, but then we realized that this is
very much not a hot path and doing in the the wrapper is just fine.

Only whitespace changes.

[5/10] Compiling C object src/systemd/login.cpython-313-x86_64-linux-gnu.so.p/login.c.o
../src/systemd/login.c:321:1: warning: missing initializer for field ‘m_slots’ of ‘struct PyModuleDef’ [-Wmissing-field-initializers]
 321 | };
 | ^
In file included from /usr/include/python3.13/Python.h:95,
 from ../src/systemd/login.c:6:
/usr/include/python3.13/moduleobject.h:113:21: note: ‘m_slots’ declared here
 113 | PyModuleDef_Slot *m_slots;
 | ^~~~~~~

[6/18] Compiling C object src/systemd/_daemon.cpython-313-x86_64-linux-gnu.so.p/_daemon.c.o
../src/systemd/_daemon.c:415:37: warning: cast between incompatible function types from ‘PyObject * (*)(PyObject *, PyObject *, PyObject *)’ {aka ‘struct _object * (*)(struct _object *, struct _object *, struct _object *)’} to ‘PyObject * (*)(PyObject *, PyObject *)’ {aka ‘struct _object * (*)(struct _object *, struct _object *)’} [-Wcast-function-type]
 415 | { "notify", (PyCFunction) notify, METH_VARARGS | METH_KEYWORDS, notify__doc__ },
 | ^
../src/systemd/_daemon.c:416:37: warning: cast between incompatible function types from ‘PyObject * (*)(PyObject *, PyObject *, PyObject *)’ {aka ‘struct _object * (*)(struct _object *, struct _object *, struct _object *)’} to ‘PyObject * (*)(PyObject *, PyObject *)’ {aka ‘struct _object * (*)(struct _object *, struct _object *)’} [-Wcast-function-type]
 416 | { "_listen_fds", (PyCFunction) listen_fds, METH_VARARGS | METH_KEYWORDS, listen_fds__doc__ },
 | ^
../src/systemd/_daemon.c:417:37: warning: cast between incompatible function types from ‘PyObject * (*)(PyObject *, PyObject *, PyObject *)’ {aka ‘struct _object * (*)(struct _object *, struct _object *, struct _object *)’} to ‘PyObject * (*)(PyObject *, PyObject *)’ {aka ‘struct _object * (*)(struct _object *, struct _object *)’} [-Wcast-function-type]
 417 | { "_listen_fds_with_names", (PyCFunction) listen_fds_with_names,
 | ^
This is a problem in the Python C API... They should have used a union type.

One-letter name is fine for a local variable, but it seems iffy to name
a structure field like this.

Since Python 3.0 it is an alias for OSError.

They were a 1:1 mapping anyway.

We're not going to be compiling any other C code, so let's simplify
this.

systemd headers should be included using <>.
And use a single include of Python.h and define PY_SSIZE_T_CLEAN
before it, so that we're using a consistent API everywhere.