Address review

Author: sobolevn

Doc/library/sys.rst

@@ -1189,9 +1189,10 @@ always available. Unless explicitly noted otherwise, all variables are read-only
    this implementation supports multiple isolated interpreters.
    It is ``True`` for CPython on most platforms.  Platforms with
    this support implement the low-level :mod:`!_interpreters` module.
-   
-   .. seealso:
-       :pep:`684`, :pep:`734`, and :mod:`concurrent.interpreters`.
+
+   .. seealso::
+
+      :pep:`684`, :pep:`734`, and :mod:`concurrent.interpreters`.
 
    :data:`sys.implementation` may contain additional attributes specific to
    the Python implementation.  These non-standard attributes must start with

Lib/test/test_sys.py

@@ -1089,9 +1089,17 @@ def test_implementation(self):
                          sys.implementation.name.lower())
 
         # https://peps.python.org/pep-0734
-        self.assertIsInstance(sys.implementation.supports_isolated_interpreters, bool)
+        sii = sys.implementation.supports_isolated_interpreters
+        self.assertIsInstance(sii, bool)
         if test.support.check_impl_detail(cpython=True):
-            self.assertIs(sys.implementation.supports_isolated_interpreters, True)
+            if (
+                test.support.is_apple_mobile
+                or test.support.is_emscripten
+                or test.support.is_wasi
+            ):
+                self.assertFalse(sii)
+            else:
+                self.assertTrue(sii)
 
     @test.support.cpython_only
     def test_debugmallocstats(self):

Python/sysmodule.c

@@ -3602,8 +3602,17 @@ make_impl_info(PyObject *version_info)
         goto error;
 #endif
 
-    res = PyDict_SetItemString(impl_info, "supports_isolated_interpreters",
-                               Py_NewRef(Py_True));  // PEP-734
+    // PEP-734
+#if defined(__wasi__) || defined(__EMSCRIPTEN__)
+    // It is not enabled on WASM builds just yet
+    value = Py_NewRef(Py_False);
+#elif defined(__APPLE__) && defined(TARGET_OS_IPHONE)
+    // It is not enabled on iOS just yet
+    value = Py_NewRef(Py_False);
+#else
+    value = Py_NewRef(Py_True);
+#endif
+    res = PyDict_SetItemString(impl_info, "supports_isolated_interpreters", value);
     if (res < 0) {
         goto error;
     }