Support specifying object to lock in Argument Clinic's `@critical_section` directive

[colesbury]

Feature or enhancement

#111903 added support for the @critical_section directive to Argument Clinic. It currently assumes that the first argument is the one that should be locked. This is a good default, but there are at least a few cases where we want to lock a different argument.

For example, in the _weakref module, we generally want to lock the object argument, not the _weakref module itself.

Let's add support for specifying the argument to lock. For example,

/*[clinic input]
@critical_section object
_weakref.getweakrefs
    object: object
    /

Return a list of all weak reference objects pointing to 'object'.
[clinic start generated code]*/

static PyObject *
_weakref_getweakrefs(PyObject *module, PyObject *object)
/*[clinic end generated code: output=25c7731d8e011824 input=00c6d0e5d3206693]*/

Linked PRs

• gh-112213: Add @critical_section target directive to Argument Clinic #112232
• gh-112213: Update _weakref module to use new AC feature #112250
• gh-112213: Add missing declaration of target_critical_section #112374

[colesbury]

cc @corona10 (motivated by #112189) and @erlend-aasland