PyEnum: Increase compatibility by allowing defaults etc., refinement

The change has been tested with Python 3.6 to 3.11.0b4 .

The enum_310.py warning triggers now only when on 3.11.0 final.

The enumFlagInfo empty check was simplified by removing empty
structures.

The code introspection was optimized version-specific for
Python 3.9 and Python 3.11 where optimizations were introduced.

Task-number: PYSIDE-1735
Change-Id: Ic5e25fd4edae0ab92aad291a8067c9dcccd5acb8
Reviewed-by: Shyamnath Premnadh <Shyamnath.Premnadh@qt.io>
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>
(cherry picked from commit 615d6a820137b31f03295e884f58cd46aadf5032)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

3 files changed, 38 insertions, 20 deletions

diff --git a/sources/shiboken6/generator/shiboken/cppgenerator.cpp b/sources/shiboken6/generator/shiboken/cppgenerator.cpp
index 6d88957f5..25d16615a 100644
--- a/sources/shiboken6/generator/shiboken/cppgenerator.cpp
+++ b/sources/shiboken6/generator/shiboken/cppgenerator.cpp
@@ -696,11 +696,13 @@ void CppGenerator::generateClass(TextStream &s, const GeneratorContext &classCon
     for (const auto &entry : qAsConst(classEnums))
         sorter.append(BuildEnumFlagInfo(entry.typeEntry()));
     sorter.sort();
-    s << "static const char *" << className << "_EnumFlagInfo[] = {\n" << indent;
-    for (const auto &entry : qAsConst(sorter))
-        s << entry << ",\n";
-    s << NULL_PTR << " // Sentinel\n"
-        << outdent << "};\n\n";
+    if (!sorter.empty()) {
+        s << "static const char *" << className << "_EnumFlagInfo[] = {\n" << indent;
+        for (const auto &entry : qAsConst(sorter))
+            s << entry << ",\n";
+        s << NULL_PTR << " // Sentinel\n"
+            << outdent << "};\n\n";
+    }
 
     // Write methods definition
     writePyMethodDefs(s, className, methodsDefinitions, typeEntry->isValue());
@@ -5964,7 +5966,7 @@ void CppGenerator::writeClassRegister(TextStream &s,
     metaClass->getEnumsFromInvisibleNamespacesToBeGenerated(&classEnums);
 
     writeEnumsInitialization(s, classEnums, ErrorReturn::Void);
-    if (!classContext.forSmartPointer())
+    if (!classContext.forSmartPointer() && !classEnums.isEmpty())
         s << "SbkObjectType_SetEnumFlagInfo(pyType, " << chopType(pyTypeName)
             << "_EnumFlagInfo);\n";
 
diff --git a/sources/shiboken6/libshiboken/sbkfeature_base.cpp b/sources/shiboken6/libshiboken/sbkfeature_base.cpp
index e8e19ac72..770735e5c 100644
--- a/sources/shiboken6/libshiboken/sbkfeature_base.cpp
+++ b/sources/shiboken6/libshiboken/sbkfeature_base.cpp
@@ -137,7 +137,7 @@ SelectableFeatureHook initSelectableFeature(SelectableFeatureHook func)
     PyErr_Restore(error_type, error_value, error_traceback);
 }
 
-// PYTHON 3.11
+// Python 3.11
 static int const PRECALL = 166;
 // we have "big instructins" with gaps after them
 static int const LOAD_ATTR_GAP = 4 * 2;
@@ -149,30 +149,45 @@ static int const CALL_METHOD = 161;
 static int const CALL_FUNCTION = 131;
 static int const LOAD_ATTR = 106;
 
+static int _getVersion()
+{
+    static PyObject *const sysmodule = PyImport_AddModule("sys");
+    static PyObject *const version = PyObject_GetAttrString(sysmodule, "version_info");
+    static PyObject *const major = PyTuple_GetItem(version, 0);
+    static PyObject *const minor = PyTuple_GetItem(version, 1);
+    static auto number = PyLong_AsLong(major) * 1000 + PyLong_AsLong(minor);
+    return number;
+}
+
 static bool currentOpcode_Is_CallMethNoArgs()
 {
     // We look into the currently active operation if we are going to call
     // a method with zero arguments.
+    auto *frame = PyEval_GetFrame();
+#if PY_VERSION_HEX >= 0x03090000 && !Py_LIMITED_API
+    auto *f_code = PyFrame_GetCode(frame);
+#else
     static PyObject *const _f_code = Shiboken::String::createStaticString("f_code");
+    AutoDecRef dec_f_code(PyObject_GetAttr(reinterpret_cast<PyObject *>(frame), _f_code));
+    auto *f_code = dec_f_code.object();
+#endif
+#if PY_VERSION_HEX >= 0x030B0000 && !Py_LIMITED_API
+    AutoDecRef dec_co_code(PyCode_GetCode(f_code));
+    Py_ssize_t f_lasti = PyFrame_GetLasti(frame);
+#else
     static PyObject *const _f_lasti = Shiboken::String::createStaticString("f_lasti");
     static PyObject *const _co_code = Shiboken::String::createStaticString("co_code");
-    auto *frame = reinterpret_cast<PyObject *>(PyEval_GetFrame());
-    // We use the limited API for frame and code objects.
-    AutoDecRef f_code(PyObject_GetAttr(frame, _f_code));
-    AutoDecRef dec_f_lasti(PyObject_GetAttr(frame, _f_lasti));
+    AutoDecRef dec_co_code(PyObject_GetAttr(reinterpret_cast<PyObject *>(f_code), _co_code));
+    AutoDecRef dec_f_lasti(PyObject_GetAttr(reinterpret_cast<PyObject *>(frame), _f_lasti));
     Py_ssize_t f_lasti = PyLong_AsSsize_t(dec_f_lasti);
-    AutoDecRef dec_co_code(PyObject_GetAttr(f_code, _co_code));
+#endif
     Py_ssize_t code_len;
     char *co_code{};
     PyBytes_AsStringAndSize(dec_co_code, &co_code, &code_len);
     uint8_t opcode1 = co_code[f_lasti];
     uint8_t opcode2 = co_code[f_lasti + 2];
     uint8_t oparg2 = co_code[f_lasti + 3];
-    static PyObject *sysmodule = PyImport_AddModule("sys");
-    static PyObject *version = PyObject_GetAttrString(sysmodule, "version_info");
-    static PyObject *major = PyTuple_GetItem(version, 0);
-    static PyObject *minor = PyTuple_GetItem(version, 1);
-    auto number = PyLong_AsLong(major) * 1000 + PyLong_AsLong(minor);
+    static auto number = _getVersion();
     if (number < 3007)
         return opcode1 == LOAD_ATTR && opcode2 == CALL_FUNCTION && oparg2 == 0;
     if (number < 3011)
@@ -270,7 +285,7 @@ PyObject *mangled_type_getattro(PyTypeObject *type, PyObject *name)
             auto sotp = PepType_SOTP(type_base);
             // The EnumFlagInfo structure tells us if there are Enums at all.
             const char **enumFlagInfo = sotp->enumFlagInfo;
-            if (!(enumFlagInfo && enumFlagInfo[0]))
+            if (!(enumFlagInfo))
                 continue;
             if (!sotp->flagsDict)
                 _initFlagsDict(sotp);
diff --git a/sources/shiboken6/shibokenmodule/files.dir/shibokensupport/signature/parser.py b/sources/shiboken6/shibokenmodule/files.dir/shibokensupport/signature/parser.py
index 8f098ec13..7c2237fc3 100644
--- a/sources/shiboken6/shibokenmodule/files.dir/shibokensupport/signature/parser.py
+++ b/sources/shiboken6/shibokenmodule/files.dir/shibokensupport/signature/parser.py
@@ -104,8 +104,9 @@ def _get_flag_enum_option():
                       f"The file pep384_issue33738.cpp should be removed ASAP! ***")
     # PYSIDE-1735: Emit a warning when we may update enum_310.py
     if pymaxver and pymaxver > (3, 10):
-        warnings.warn(f"\n    *** Python is at version {'.'.join(map(str, pymaxver))} now. "
-                      f"Please check if enum_310.py should be updated! ***")
+        if sys.version_info >= (3, 11, 0) and sys.version_info.releaselevel == "final":
+            warnings.warn(f"\n    *** Python is at version {'.'.join(map(str, pymaxver))} now. "
+                          f"Please check if enum_310.py should be updated! ***")
     # PYSIDE-1735: Emit a warning when we may update enum_310.py
     if ver[:2] >= (7, 0):
         warnings.warn(f"\n    *** PySide is at version {'.'.join(map(str, ver[:2]))} now. "