[3.13] Revert "gh-115432: Add critical section variant that handles a NULL object (GH-115433)" (GH-118861) (#118872)

This reverts commit ad4f909.

The API ended up not being used.
(cherry picked from commit 46c8081)

Co-authored-by: Sam Gross <[email protected]>

Author: miss-islington

Include/internal/pycore_critical_section.h

@@ -99,15 +99,6 @@ extern "C" {
         _PyCriticalSection_End(&_cs);                                   \
     }
 
-# define Py_XBEGIN_CRITICAL_SECTION(op)                                 \
-    {                                                                   \
-        _PyCriticalSection _cs_opt = {0};                               \
-        _PyCriticalSection_XBegin(&_cs_opt, _PyObject_CAST(op))
-
-# define Py_XEND_CRITICAL_SECTION()                                     \
-        _PyCriticalSection_XEnd(&_cs_opt);                              \
-    }
-
 # define Py_BEGIN_CRITICAL_SECTION2(a, b)                               \
     {                                                                   \
         _PyCriticalSection2 _cs2;                                       \
@@ -144,8 +135,6 @@ extern "C" {
 # define Py_BEGIN_CRITICAL_SECTION_MUT(mut)
 # define Py_BEGIN_CRITICAL_SECTION(op)
 # define Py_END_CRITICAL_SECTION()
-# define Py_XBEGIN_CRITICAL_SECTION(op)
-# define Py_XEND_CRITICAL_SECTION()
 # define Py_BEGIN_CRITICAL_SECTION2(a, b)
 # define Py_END_CRITICAL_SECTION2()
 # define _Py_CRITICAL_SECTION_ASSERT_MUTEX_LOCKED(mutex)
@@ -202,16 +191,6 @@ _PyCriticalSection_Begin(_PyCriticalSection *c, PyMutex *m)
     }
 }
 
-static inline void
-_PyCriticalSection_XBegin(_PyCriticalSection *c, PyObject *op)
-{
-#ifdef Py_GIL_DISABLED
-    if (op != NULL) {
-        _PyCriticalSection_Begin(c, &_PyObject_CAST(op)->ob_mutex);
-    }
-#endif
-}
-
 // Removes the top-most critical section from the thread's stack of critical
 // sections. If the new top-most critical section is inactive, then it is
 // resumed.
@@ -234,14 +213,6 @@ _PyCriticalSection_End(_PyCriticalSection *c)
     _PyCriticalSection_Pop(c);
 }
 
-static inline void
-_PyCriticalSection_XEnd(_PyCriticalSection *c)
-{
-    if (c->mutex) {
-        _PyCriticalSection_End(c);
-    }
-}
-
 static inline void
 _PyCriticalSection2_Begin(_PyCriticalSection2 *c, PyMutex *m1, PyMutex *m2)
 {

Modules/_testinternalcapi/test_critical_sections.c

@@ -49,15 +49,6 @@ test_critical_sections(PyObject *self, PyObject *Py_UNUSED(args))
     Py_END_CRITICAL_SECTION2();
     assert_nogil(!PyMutex_IsLocked(&d2->ob_mutex));
 
-    // Optional variant behaves the same if the object is non-NULL
-    Py_XBEGIN_CRITICAL_SECTION(d1);
-    assert_nogil(PyMutex_IsLocked(&d1->ob_mutex));
-    Py_XEND_CRITICAL_SECTION();
-
-    // No-op
-    Py_XBEGIN_CRITICAL_SECTION(NULL);
-    Py_XEND_CRITICAL_SECTION();
-
     Py_DECREF(d2);
     Py_DECREF(d1);
     Py_RETURN_NONE;