bpo-40514: Drop EXPERIMENTAL_ISOLATED_SUBINTERPRETERS (gh-93185)

This was added for bpo-40514 (gh-84694) to test out a per-interpreter GIL. However, it has since proven unnecessary to keep the experiment in the repo. (It can be done as a branch in a fork like normal.) So here we are removing:

* the configure option
* the macro
* the code enabled by the macro

2 files changed, 3 insertions, 39 deletions

diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 37ac886..2566d21 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -54,11 +54,6 @@ typedef struct PySlot_Offset {
 } PySlot_Offset;
 
 
-/* bpo-40521: Interned strings are shared by all subinterpreters */
-#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-#  define INTERN_NAME_STRINGS
-#endif
-
 static PyObject *
 slot_tp_new(PyTypeObject *type, PyObject *args, PyObject *kwds);
 
@@ -4027,7 +4022,7 @@ type_setattro(PyTypeObject *type, PyObject *name, PyObject *value)
             if (name == NULL)
                 return -1;
         }
-#ifdef INTERN_NAME_STRINGS
+        /* bpo-40521: Interned strings are shared by all subinterpreters */
         if (!PyUnicode_CHECK_INTERNED(name)) {
             PyUnicode_InternInPlace(&name);
             if (!PyUnicode_CHECK_INTERNED(name)) {
@@ -4037,7 +4032,6 @@ type_setattro(PyTypeObject *type, PyObject *name, PyObject *value)
                 return -1;
             }
         }
-#endif
     }
     else {
         /* Will fail in _PyObject_GenericSetAttrWithDict. */
@@ -8474,17 +8468,11 @@ _PyTypes_InitSlotDefs(void)
     for (slotdef *p = slotdefs; p->name; p++) {
         /* Slots must be ordered by their offset in the PyHeapTypeObject. */
         assert(!p[1].name || p->offset <= p[1].offset);
-#ifdef INTERN_NAME_STRINGS
+        /* bpo-40521: Interned strings are shared by all subinterpreters */
         p->name_strobj = PyUnicode_InternFromString(p->name);
         if (!p->name_strobj || !PyUnicode_CHECK_INTERNED(p->name_strobj)) {
             return _PyStatus_NO_MEMORY();
         }
-#else
-        p->name_strobj = PyUnicode_FromString(p->name);
-        if (!p->name_strobj) {
-            return _PyStatus_NO_MEMORY();
-        }
-#endif
     }
     slotdefs_initialized = 1;
     return _PyStatus_OK();
@@ -8509,24 +8497,17 @@ update_slot(PyTypeObject *type, PyObject *name)
     int offset;
 
     assert(PyUnicode_CheckExact(name));
-#ifdef INTERN_NAME_STRINGS
     assert(PyUnicode_CHECK_INTERNED(name));
-#endif
 
     assert(slotdefs_initialized);
     pp = ptrs;
     for (p = slotdefs; p->name; p++) {
         assert(PyUnicode_CheckExact(p->name_strobj));
         assert(PyUnicode_CheckExact(name));
-#ifdef INTERN_NAME_STRINGS
+        /* bpo-40521: Using interned strings. */
         if (p->name_strobj == name) {
             *pp++ = p;
         }
-#else
-        if (p->name_strobj == name || _PyUnicode_EQ(p->name_strobj, name)) {
-            *pp++ = p;
-        }
-#endif
     }
     *pp = NULL;
     for (pp = ptrs; *pp; pp++) {
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index f712fbf..d0e4bcd 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -190,11 +190,6 @@ extern "C" {
 #  define OVERALLOCATE_FACTOR 4
 #endif
 
-/* bpo-40521: Interned strings are shared by all interpreters. */
-#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-#  define INTERNED_STRINGS
-#endif
-
 /* This dictionary holds all interned unicode strings.  Note that references
    to strings in this dictionary are *not* counted in the string's ob_refcnt.
    When the interned string reaches a refcnt of 0 the string deallocation
@@ -203,9 +198,7 @@ extern "C" {
    Another way to look at this is that to say that the actual reference
    count of a string is:  s->ob_refcnt + (s->state ? 2 : 0)
 */
-#ifdef INTERNED_STRINGS
 static PyObject *interned = NULL;
-#endif
 
 /* Forward declaration */
 static inline int
@@ -1530,7 +1523,6 @@ unicode_dealloc(PyObject *unicode)
     }
 #endif
 
-#ifdef INTERNED_STRINGS
     if (PyUnicode_CHECK_INTERNED(unicode)) {
         /* Revive the dead object temporarily. PyDict_DelItem() removes two
            references (key and value) which were ignored by
@@ -1546,7 +1538,6 @@ unicode_dealloc(PyObject *unicode)
         assert(Py_REFCNT(unicode) == 1);
         Py_SET_REFCNT(unicode, 0);
     }
-#endif
 
     if (_PyUnicode_HAS_UTF8_MEMORY(unicode)) {
         PyObject_Free(_PyUnicode_UTF8(unicode));
@@ -10568,13 +10559,11 @@ _PyUnicode_EqualToASCIIId(PyObject *left, _Py_Identifier *right)
     if (PyUnicode_CHECK_INTERNED(left))
         return 0;
 
-#ifdef INTERNED_STRINGS
     assert(_PyUnicode_HASH(right_uni) != -1);
     Py_hash_t hash = _PyUnicode_HASH(left);
     if (hash != -1 && hash != _PyUnicode_HASH(right_uni)) {
         return 0;
     }
-#endif
 
     return unicode_compare_eq(left, right_uni);
 }
@@ -14645,7 +14634,6 @@ PyUnicode_InternInPlace(PyObject **p)
         return;
     }
 
-#ifdef INTERNED_STRINGS
     if (interned == NULL) {
         interned = PyDict_New();
         if (interned == NULL) {
@@ -14671,11 +14659,6 @@ PyUnicode_InternInPlace(PyObject **p)
        this. */
     Py_SET_REFCNT(s, Py_REFCNT(s) - 2);
     _PyUnicode_STATE(s).interned = 1;
-#else
-    // PyDict expects that interned strings have their hash
-    // (PyASCIIObject.hash) already computed.
-    (void)unicode_hash(s);
-#endif
 }
 
 // Function kept for the stable ABI.