gh-116417: Add _testlimitedcapi C extension (#116419)

Add a new C extension "_testlimitedcapi" which is only built with the
limited C API.

Move heaptype_relative.c and vectorcall_limited.c from
Modules/_testcapi/ to Modules/_testlimitedcapi/.

* configure: add _testlimitedcapi test extension.
* Update generate_stdlib_module_names.py.
* Update make check-c-globals.

Co-authored-by: Erlend E. Aasland <erlend.aasland@protonmail.com>

Lib/test/support/__init__.py

@@ -1153,8 +1153,9 @@ def refcount_test(test):
 def requires_limited_api(test):
     try:
         import _testcapi
+        import _testlimitedcapi
     except ImportError:
-        return unittest.skip('needs _testcapi module')(test)
+        return unittest.skip('needs _testcapi and _testlimitedcapi modules')(test)
     return test
 
 def requires_specialization(test):

Lib/test/test_call.py

@@ -5,6 +5,10 @@
     import _testcapi
 except ImportError:
     _testcapi = None
+try:
+    import _testlimitedcapi
+except ImportError:
+    _testlimitedcapi = None
 import struct
 import collections
 import itertools
@@ -837,12 +841,12 @@ def get_a(x):
     @requires_limited_api
     def test_vectorcall_limited_incoming(self):
         from _testcapi import pyobject_vectorcall
-        obj = _testcapi.LimitedVectorCallClass()
+        obj = _testlimitedcapi.LimitedVectorCallClass()
         self.assertEqual(pyobject_vectorcall(obj, (), ()), "vectorcall called")
 
     @requires_limited_api
     def test_vectorcall_limited_outgoing(self):
-        from _testcapi import call_vectorcall
+        from _testlimitedcapi import call_vectorcall
 
         args_captured = []
         kwargs_captured = []
@@ -858,7 +862,7 @@ def f(*args, **kwargs):
 
     @requires_limited_api
     def test_vectorcall_limited_outgoing_method(self):
-        from _testcapi import call_vectorcall_method
+        from _testlimitedcapi import call_vectorcall_method
 
         args_captured = []
         kwargs_captured = []

Lib/test/test_capi/test_misc.py

@@ -47,6 +47,7 @@
 # Skip this test if the _testcapi module isn't available.
 _testcapi = import_helper.import_module('_testcapi')
 
+import _testlimitedcapi
 import _testinternalcapi
 
 
@@ -1124,7 +1125,7 @@ def test_heaptype_relative_sizes(self):
         # Test subclassing using "relative" basicsize, see PEP 697
         def check(extra_base_size, extra_size):
             Base, Sub, instance, data_ptr, data_offset, data_size = (
-                _testcapi.make_sized_heaptypes(
+                _testlimitedcapi.make_sized_heaptypes(
                     extra_base_size, -extra_size))
 
             # no alignment shenanigans when inheriting directly
@@ -1152,11 +1153,11 @@ def check(extra_base_size, extra_size):
 
                 # we don't reserve (requested + alignment) or more data
                 self.assertLess(data_size - extra_size,
-                                _testcapi.ALIGNOF_MAX_ALIGN_T)
+                                _testlimitedcapi.ALIGNOF_MAX_ALIGN_T)
 
             # The offsets/sizes we calculated should be aligned.
-            self.assertEqual(data_offset % _testcapi.ALIGNOF_MAX_ALIGN_T, 0)
-            self.assertEqual(data_size % _testcapi.ALIGNOF_MAX_ALIGN_T, 0)
+            self.assertEqual(data_offset % _testlimitedcapi.ALIGNOF_MAX_ALIGN_T, 0)
+            self.assertEqual(data_size % _testlimitedcapi.ALIGNOF_MAX_ALIGN_T, 0)
 
         sizes = sorted({0, 1, 2, 3, 4, 7, 8, 123,
                         object.__basicsize__,
@@ -1182,7 +1183,7 @@ def test_heaptype_inherit_itemsize(self):
                         object.__basicsize__+1})
         for extra_size in sizes:
             with self.subTest(extra_size=extra_size):
-                Sub = _testcapi.subclass_var_heaptype(
+                Sub = _testlimitedcapi.subclass_var_heaptype(
                     _testcapi.HeapCCollection, -extra_size, 0, 0)
                 collection = Sub(1, 2, 3)
                 collection.set_data_to_3s()
@@ -1196,7 +1197,7 @@ def test_heaptype_invalid_inheritance(self):
         with self.assertRaises(SystemError,
                                msg="Cannot extend variable-size class without "
                                + "Py_TPFLAGS_ITEMS_AT_END"):
-            _testcapi.subclass_heaptype(int, -8, 0)
+            _testlimitedcapi.subclass_heaptype(int, -8, 0)
 
     def test_heaptype_relative_members(self):
         """Test HeapCCollection subclasses work properly"""
@@ -1209,7 +1210,7 @@ def test_heaptype_relative_members(self):
                 for offset in sizes:
                     with self.subTest(extra_base_size=extra_base_size, extra_size=extra_size, offset=offset):
                         if offset < extra_size:
-                            Sub = _testcapi.make_heaptype_with_member(
+                            Sub = _testlimitedcapi.make_heaptype_with_member(
                                 extra_base_size, -extra_size, offset, True)
                             Base = Sub.mro()[1]
                             instance = Sub()
@@ -1228,29 +1229,29 @@ def test_heaptype_relative_members(self):
                                 instance.set_memb_relative(0)
                         else:
                             with self.assertRaises(SystemError):
-                                Sub = _testcapi.make_heaptype_with_member(
+                                Sub = _testlimitedcapi.make_heaptype_with_member(
                                     extra_base_size, -extra_size, offset, True)
                         with self.assertRaises(SystemError):
-                            Sub = _testcapi.make_heaptype_with_member(
+                            Sub = _testlimitedcapi.make_heaptype_with_member(
                                 extra_base_size, extra_size, offset, True)
                 with self.subTest(extra_base_size=extra_base_size, extra_size=extra_size):
                     with self.assertRaises(SystemError):
-                        Sub = _testcapi.make_heaptype_with_member(
+                        Sub = _testlimitedcapi.make_heaptype_with_member(
                             extra_base_size, -extra_size, -1, True)
 
     def test_heaptype_relative_members_errors(self):
         with self.assertRaisesRegex(
                 SystemError,
                 r"With Py_RELATIVE_OFFSET, basicsize must be negative"):
-            _testcapi.make_heaptype_with_member(0, 1234, 0, True)
+            _testlimitedcapi.make_heaptype_with_member(0, 1234, 0, True)
         with self.assertRaisesRegex(
                 SystemError, r"Member offset out of range \(0\.\.-basicsize\)"):
-            _testcapi.make_heaptype_with_member(0, -8, 1234, True)
+            _testlimitedcapi.make_heaptype_with_member(0, -8, 1234, True)
         with self.assertRaisesRegex(
                 SystemError, r"Member offset out of range \(0\.\.-basicsize\)"):
-            _testcapi.make_heaptype_with_member(0, -8, -1, True)
+            _testlimitedcapi.make_heaptype_with_member(0, -8, -1, True)
 
-        Sub = _testcapi.make_heaptype_with_member(0, -8, 0, True)
+        Sub = _testlimitedcapi.make_heaptype_with_member(0, -8, 0, True)
         instance = Sub()
         with self.assertRaisesRegex(
                 SystemError, r"PyMember_GetOne used with Py_RELATIVE_OFFSET"):
@@ -2264,10 +2265,19 @@ def test_gilstate_matches_current(self):
         _testcapi.test_current_tstate_matches()
 
 
+def get_test_funcs(mod, exclude_prefix=None):
+    funcs = {}
+    for name in dir(mod):
+        if not name.startswith('test_'):
+            continue
+        if exclude_prefix is not None and name.startswith(exclude_prefix):
+            continue
+        funcs[name] = getattr(mod, name)
+    return funcs
+
+
 class Test_testcapi(unittest.TestCase):
-    locals().update((name, getattr(_testcapi, name))
-                    for name in dir(_testcapi)
-                    if name.startswith('test_'))
+    locals().update(get_test_funcs(_testcapi))
 
     # Suppress warning from PyUnicode_FromUnicode().
     @warnings_helper.ignore_warnings(category=DeprecationWarning)
@@ -2278,11 +2288,13 @@ def test_version_api_data(self):
         self.assertEqual(_testcapi.Py_Version, sys.hexversion)
 
 
+class Test_testlimitedcapi(unittest.TestCase):
+    locals().update(get_test_funcs(_testlimitedcapi))
+
+
 class Test_testinternalcapi(unittest.TestCase):
-    locals().update((name, getattr(_testinternalcapi, name))
-                    for name in dir(_testinternalcapi)
-                    if name.startswith('test_')
-                    and not name.startswith('test_lock_'))
+    locals().update(get_test_funcs(_testinternalcapi,
+                                   exclude_prefix='test_lock_'))
 
 
 @threading_helper.requires_working_threading()

Modules/Setup.stdlib.in

@@ -162,7 +162,8 @@
 @MODULE__XXTESTFUZZ_TRUE@_xxtestfuzz _xxtestfuzz/_xxtestfuzz.c _xxtestfuzz/fuzzer.c
 @MODULE__TESTBUFFER_TRUE@_testbuffer _testbuffer.c
 @MODULE__TESTINTERNALCAPI_TRUE@_testinternalcapi _testinternalcapi.c _testinternalcapi/test_lock.c _testinternalcapi/pytime.c _testinternalcapi/set.c _testinternalcapi/test_critical_sections.c
-@MODULE__TESTCAPI_TRUE@_testcapi _testcapimodule.c _testcapi/vectorcall.c _testcapi/vectorcall_limited.c _testcapi/heaptype.c _testcapi/abstract.c _testcapi/bytearray.c _testcapi/bytes.c _testcapi/unicode.c _testcapi/dict.c _testcapi/set.c _testcapi/list.c _testcapi/tuple.c _testcapi/getargs.c _testcapi/datetime.c _testcapi/docstring.c _testcapi/mem.c _testcapi/watchers.c _testcapi/long.c _testcapi/float.c _testcapi/complex.c _testcapi/numbers.c _testcapi/structmember.c _testcapi/exceptions.c _testcapi/code.c _testcapi/buffer.c _testcapi/pyatomic.c _testcapi/pyos.c _testcapi/file.c _testcapi/codec.c _testcapi/immortal.c _testcapi/heaptype_relative.c _testcapi/gc.c _testcapi/sys.c _testcapi/hash.c _testcapi/time.c
+@MODULE__TESTCAPI_TRUE@_testcapi _testcapimodule.c _testcapi/vectorcall.c _testcapi/heaptype.c _testcapi/abstract.c _testcapi/bytearray.c _testcapi/bytes.c _testcapi/unicode.c _testcapi/dict.c _testcapi/set.c _testcapi/list.c _testcapi/tuple.c _testcapi/getargs.c _testcapi/datetime.c _testcapi/docstring.c _testcapi/mem.c _testcapi/watchers.c _testcapi/long.c _testcapi/float.c _testcapi/complex.c _testcapi/numbers.c _testcapi/structmember.c _testcapi/exceptions.c _testcapi/code.c _testcapi/buffer.c _testcapi/pyatomic.c _testcapi/pyos.c _testcapi/file.c _testcapi/codec.c _testcapi/immortal.c _testcapi/gc.c _testcapi/sys.c _testcapi/hash.c _testcapi/time.c
+@MODULE__TESTLIMITEDCAPI_TRUE@_testlimitedcapi _testlimitedcapi.c _testlimitedcapi/vectorcall_limited.c _testlimitedcapi/heaptype_relative.c
 @MODULE__TESTCLINIC_TRUE@_testclinic _testclinic.c
 @MODULE__TESTCLINIC_LIMITED_TRUE@_testclinic_limited _testclinic_limited.c
 

Modules/_testcapi/parts.h

@@ -61,7 +61,4 @@ int _PyTestCapi_Init_Sys(PyObject *module);
 int _PyTestCapi_Init_Hash(PyObject *module);
 int _PyTestCapi_Init_Time(PyObject *module);
 
-int _PyTestCapi_Init_VectorcallLimited(PyObject *module);
-int _PyTestCapi_Init_HeaptypeRelative(PyObject *module);
-
 #endif // Py_TESTCAPI_PARTS_H

Modules/_testcapimodule.c

@@ -4098,12 +4098,6 @@ PyInit__testcapi(void)
     if (_PyTestCapi_Init_PyAtomic(m) < 0) {
         return NULL;
     }
-    if (_PyTestCapi_Init_VectorcallLimited(m) < 0) {
-        return NULL;
-    }
-    if (_PyTestCapi_Init_HeaptypeRelative(m) < 0) {
-        return NULL;
-    }
     if (_PyTestCapi_Init_Hash(m) < 0) {
         return NULL;
     }

Modules/_testlimitedcapi.c

@@ -0,0 +1,36 @@
+/*
+ * Test the limited C API.
+ *
+ * The 'test_*' functions exported by this module are run as part of the
+ * standard Python regression test, via Lib/test/test_capi.py.
+ */
+
+#include "_testlimitedcapi/parts.h"
+
+static PyMethodDef TestMethods[] = {
+    {NULL, NULL} /* sentinel */
+};
+
+static struct PyModuleDef _testlimitedcapimodule = {
+    PyModuleDef_HEAD_INIT,
+    .m_name = "_testlimitedcapi",
+    .m_size = 0,
+    .m_methods = TestMethods,
+};
+
+PyMODINIT_FUNC
+PyInit__testlimitedcapi(void)
+{
+    PyObject *mod = PyModule_Create(&_testlimitedcapimodule);
+    if (mod == NULL) {
+        return NULL;
+    }
+
+    if (_PyTestCapi_Init_VectorcallLimited(mod) < 0) {
+        return NULL;
+    }
+    if (_PyTestCapi_Init_HeaptypeRelative(mod) < 0) {
+        return NULL;
+    }
+    return mod;
+}

Modules/_testcapi/heaptype_relative.c → Modules/_testlimitedcapi/heaptype_relative.c

@@ -1,9 +1,3 @@
-#include "pyconfig.h"   // Py_GIL_DISABLED
-
-#ifndef Py_GIL_DISABLED
-#define Py_LIMITED_API 0x030c0000 // 3.12
-#endif
-
 #include "parts.h"
 #include <stddef.h>               // max_align_t
 #include <string.h>               // memset

Modules/_testlimitedcapi/parts.h

@@ -0,0 +1,27 @@
+#ifndef Py_TESTLIMITEDCAPI_PARTS_H
+#define Py_TESTLIMITEDCAPI_PARTS_H
+
+// Always enable assertions
+#undef NDEBUG
+
+#include "pyconfig.h"   // Py_GIL_DISABLED
+
+// Use the limited C API
+#ifndef Py_GIL_DISABLED
+#  define Py_LIMITED_API 0x030c0000  // 3.12
+#endif
+
+// Make sure that the internal C API cannot be used.
+#undef Py_BUILD_CORE_MODULE
+#undef Py_BUILD_CORE_BUILTIN
+
+#include "Python.h"
+
+#ifdef Py_BUILD_CORE
+#  error "Py_BUILD_CORE macro must not be defined"
+#endif
+
+int _PyTestCapi_Init_VectorcallLimited(PyObject *module);
+int _PyTestCapi_Init_HeaptypeRelative(PyObject *module);
+
+#endif // Py_TESTLIMITEDCAPI_PARTS_H