Fix: 3.11 beta support (#3923)

* Placeholder commit for 3.11 testing

* Does this fix it?

* Try suggestion

* Placeholder commit for 3.11 testing

* Does this fix it?

* Try suggestion

* fix: try using modern init for embedded interp

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* fix: error message changed in 3.11

* fix: apply logic in Python manually

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* fix autodetect dynamic attrs in 3.11

* fix: include error message if possible in error

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* ci: enable standard Python 3.11 testing

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* Make dynamic attrs condtiion exclusive to ver.

Co-authored-by: Henry Schreiner <henryschreineriii@gmail.com>

.github/workflows/ci.yml

@@ -30,6 +30,7 @@ jobs:
         - '3.6'
         - '3.9'
         - '3.10'
+        - '3.11-dev'
         - 'pypy-3.7'
         - 'pypy-3.8'
         - 'pypy-3.9'
@@ -185,8 +186,8 @@ jobs:
         - python-version: "3.9"
           python-debug: true
           valgrind: true
-      # - python-version: "3.11-dev"
-      #   python-debug: false
+        - python-version: "3.11-dev"
+          python-debug: false
 
     name: "🐍 ${{ matrix.python-version }}${{ matrix.python-debug && '-dbg' || '' }} (deadsnakes)${{ matrix.valgrind && ' • Valgrind' || '' }} • x64"
     runs-on: ubuntu-latest

.github/workflows/upstream.yml

@@ -14,7 +14,7 @@ env:
 
 jobs:
   standard:
-    name: "🐍 3.11 dev • ubuntu-latest • x64"
+    name: "🐍 3.11 latest internals • ubuntu-latest • x64"
     runs-on: ubuntu-latest
     if: "contains(github.event.pull_request.labels.*.name, 'python dev')"
 

include/pybind11/attr.h

@@ -345,9 +345,11 @@ struct type_record {
 
         bases.append((PyObject *) base_info->type);
 
-        if (base_info->type->tp_dictoffset != 0) {
-            dynamic_attr = true;
-        }
+#if PY_VERSION_HEX < 0x030B0000
+        dynamic_attr |= base_info->type->tp_dictoffset != 0;
+#else
+        dynamic_attr |= (base_info->type->tp_flags & Py_TPFLAGS_MANAGED_DICT) != 0;
+#endif
 
         if (caster) {
             base_info->implicit_casts.emplace_back(type, caster);

include/pybind11/detail/class.h

@@ -545,8 +545,12 @@ extern "C" inline int pybind11_clear(PyObject *self) {
 inline void enable_dynamic_attributes(PyHeapTypeObject *heap_type) {
     auto *type = &heap_type->ht_type;
     type->tp_flags |= Py_TPFLAGS_HAVE_GC;
+#if PY_VERSION_HEX < 0x030B0000
     type->tp_dictoffset = type->tp_basicsize;           // place dict at the end
     type->tp_basicsize += (ssize_t) sizeof(PyObject *); // and allocate enough space for it
+#else
+    type->tp_flags |= Py_TPFLAGS_MANAGED_DICT;
+#endif
     type->tp_traverse = pybind11_traverse;
     type->tp_clear = pybind11_clear;
 

include/pybind11/embed.h

@@ -86,37 +86,6 @@ inline wchar_t *widen_chars(const char *safe_arg) {
     return widened_arg;
 }
 
-/// Python 2.x/3.x-compatible version of `PySys_SetArgv`
-inline void set_interpreter_argv(int argc, const char *const *argv, bool add_program_dir_to_path) {
-    // Before it was special-cased in python 3.8, passing an empty or null argv
-    // caused a segfault, so we have to reimplement the special case ourselves.
-    bool special_case = (argv == nullptr || argc <= 0);
-
-    const char *const empty_argv[]{"\0"};
-    const char *const *safe_argv = special_case ? empty_argv : argv;
-    if (special_case) {
-        argc = 1;
-    }
-
-    auto argv_size = static_cast<size_t>(argc);
-    // SetArgv* on python 3 takes wchar_t, so we have to convert.
-    std::unique_ptr<wchar_t *[]> widened_argv(new wchar_t *[argv_size]);
-    std::vector<std::unique_ptr<wchar_t[], wide_char_arg_deleter>> widened_argv_entries;
-    widened_argv_entries.reserve(argv_size);
-    for (size_t ii = 0; ii < argv_size; ++ii) {
-        widened_argv_entries.emplace_back(widen_chars(safe_argv[ii]));
-        if (!widened_argv_entries.back()) {
-            // A null here indicates a character-encoding failure or the python
-            // interpreter out of memory. Give up.
-            return;
-        }
-        widened_argv[ii] = widened_argv_entries.back().get();
-    }
-
-    auto *pysys_argv = widened_argv.get();
-    PySys_SetArgvEx(argc, pysys_argv, static_cast<int>(add_program_dir_to_path));
-}
-
 PYBIND11_NAMESPACE_END(detail)
 
 /** \rst
@@ -146,9 +115,64 @@ inline void initialize_interpreter(bool init_signal_handlers = true,
         pybind11_fail("The interpreter is already running");
     }
 
+#if PY_VERSION_HEX < 0x030B0000
+
     Py_InitializeEx(init_signal_handlers ? 1 : 0);
 
-    detail::set_interpreter_argv(argc, argv, add_program_dir_to_path);
+    // Before it was special-cased in python 3.8, passing an empty or null argv
+    // caused a segfault, so we have to reimplement the special case ourselves.
+    bool special_case = (argv == nullptr || argc <= 0);
+
+    const char *const empty_argv[]{"\0"};
+    const char *const *safe_argv = special_case ? empty_argv : argv;
+    if (special_case) {
+        argc = 1;
+    }
+
+    auto argv_size = static_cast<size_t>(argc);
+    // SetArgv* on python 3 takes wchar_t, so we have to convert.
+    std::unique_ptr<wchar_t *[]> widened_argv(new wchar_t *[argv_size]);
+    std::vector<std::unique_ptr<wchar_t[], detail::wide_char_arg_deleter>> widened_argv_entries;
+    widened_argv_entries.reserve(argv_size);
+    for (size_t ii = 0; ii < argv_size; ++ii) {
+        widened_argv_entries.emplace_back(detail::widen_chars(safe_argv[ii]));
+        if (!widened_argv_entries.back()) {
+            // A null here indicates a character-encoding failure or the python
+            // interpreter out of memory. Give up.
+            return;
+        }
+        widened_argv[ii] = widened_argv_entries.back().get();
+    }
+
+    auto *pysys_argv = widened_argv.get();
+
+    PySys_SetArgvEx(argc, pysys_argv, static_cast<int>(add_program_dir_to_path));
+#else
+    PyConfig config;
+    PyConfig_InitIsolatedConfig(&config);
+    config.install_signal_handlers = init_signal_handlers ? 1 : 0;
+
+    PyStatus status = PyConfig_SetBytesArgv(&config, argc, const_cast<char *const *>(argv));
+    if (PyStatus_Exception(status)) {
+        // A failure here indicates a character-encoding failure or the python
+        // interpreter out of memory. Give up.
+        PyConfig_Clear(&config);
+        throw std::runtime_error(PyStatus_IsError(status) ? status.err_msg
+                                                          : "Failed to prepare CPython");
+    }
+    status = Py_InitializeFromConfig(&config);
+    PyConfig_Clear(&config);
+    if (PyStatus_Exception(status)) {
+        throw std::runtime_error(PyStatus_IsError(status) ? status.err_msg
+                                                          : "Failed to init CPython");
+    }
+    if (add_program_dir_to_path) {
+        PyRun_SimpleString("import sys, os.path; "
+                           "sys.path.insert(0, "
+                           "os.path.abspath(os.path.dirname(sys.argv[0])) "
+                           "if sys.argv and os.path.exists(sys.argv[0]) else '')");
+    }
+#endif
 }
 
 /** \rst

setup.cfg

@@ -19,6 +19,7 @@ classifiers =
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
     Programming Language :: Python :: 3.10
+    Programming Language :: Python :: 3.11
     License :: OSI Approved :: BSD License
     Programming Language :: Python :: Implementation :: PyPy
     Programming Language :: Python :: Implementation :: CPython

tests/requirements.txt

@@ -1,4 +1,4 @@
-build==0.7.0
+build==0.8.0
 numpy==1.21.5; platform_python_implementation=="PyPy" and sys_platform=="linux" and python_version=="3.7"
 numpy==1.19.3; platform_python_implementation!="PyPy" and python_version=="3.6"
 numpy==1.21.5; platform_python_implementation!="PyPy" and python_version>="3.7" and python_version<"3.10"

tests/test_methods_and_attributes.py

@@ -1,9 +1,21 @@
+import sys
+
 import pytest
 
 import env  # noqa: F401
 from pybind11_tests import ConstructorStats
 from pybind11_tests import methods_and_attributes as m
 
+NO_GETTER_MSG = (
+    "unreadable attribute" if sys.version_info < (3, 11) else "object has no getter"
+)
+NO_SETTER_MSG = (
+    "can't set attribute" if sys.version_info < (3, 11) else "object has no setter"
+)
+NO_DELETER_MSG = (
+    "can't delete attribute" if sys.version_info < (3, 11) else "object has no deleter"
+)
+
 
 def test_methods_and_attributes():
     instance1 = m.ExampleMandA()
@@ -102,32 +114,32 @@ def test_properties():
 
     with pytest.raises(AttributeError) as excinfo:
         dummy = instance.def_property_writeonly  # unused var
-    assert "unreadable attribute" in str(excinfo.value)
+    assert NO_GETTER_MSG in str(excinfo.value)
 
     instance.def_property_writeonly = 4
     assert instance.def_property_readonly == 4
 
     with pytest.raises(AttributeError) as excinfo:
         dummy = instance.def_property_impossible  # noqa: F841 unused var
-    assert "unreadable attribute" in str(excinfo.value)
+    assert NO_GETTER_MSG in str(excinfo.value)
 
     with pytest.raises(AttributeError) as excinfo:
         instance.def_property_impossible = 5
-    assert "can't set attribute" in str(excinfo.value)
+    assert NO_SETTER_MSG in str(excinfo.value)
 
 
 def test_static_properties():
     assert m.TestProperties.def_readonly_static == 1
     with pytest.raises(AttributeError) as excinfo:
         m.TestProperties.def_readonly_static = 2
-    assert "can't set attribute" in str(excinfo.value)
+    assert NO_SETTER_MSG in str(excinfo.value)
 
     m.TestProperties.def_readwrite_static = 2
     assert m.TestProperties.def_readwrite_static == 2
 
     with pytest.raises(AttributeError) as excinfo:
         dummy = m.TestProperties.def_writeonly_static  # unused var
-    assert "unreadable attribute" in str(excinfo.value)
+    assert NO_GETTER_MSG in str(excinfo.value)
 
     m.TestProperties.def_writeonly_static = 3
     assert m.TestProperties.def_readonly_static == 3
@@ -135,14 +147,14 @@ def test_static_properties():
     assert m.TestProperties.def_property_readonly_static == 3
     with pytest.raises(AttributeError) as excinfo:
         m.TestProperties.def_property_readonly_static = 99
-    assert "can't set attribute" in str(excinfo.value)
+    assert NO_SETTER_MSG in str(excinfo.value)
 
     m.TestProperties.def_property_static = 4
     assert m.TestProperties.def_property_static == 4
 
     with pytest.raises(AttributeError) as excinfo:
         dummy = m.TestProperties.def_property_writeonly_static
-    assert "unreadable attribute" in str(excinfo.value)
+    assert NO_GETTER_MSG in str(excinfo.value)
 
     m.TestProperties.def_property_writeonly_static = 5
     assert m.TestProperties.def_property_static == 5
@@ -160,7 +172,7 @@ def test_static_properties():
 
     with pytest.raises(AttributeError) as excinfo:
         dummy = instance.def_property_writeonly_static  # noqa: F841 unused var
-    assert "unreadable attribute" in str(excinfo.value)
+    assert NO_GETTER_MSG in str(excinfo.value)
 
     instance.def_property_writeonly_static = 4
     assert instance.def_property_static == 4
@@ -180,7 +192,7 @@ def test_static_properties():
     properties_override = m.TestPropertiesOverride()
     with pytest.raises(AttributeError) as excinfo:
         del properties_override.def_readonly
-    assert "can't delete attribute" in str(excinfo.value)
+    assert NO_DELETER_MSG in str(excinfo.value)
 
 
 def test_static_cls():