[Python] Only use Python Limited C API in ROOT Pythonizations library

This follows up on 4e0c7bf, swapping out the remaining use of
CPython API functions that were not inside the limited API.

In the cases where we're sill using private headers from cppyy, the
parts of these headers that don't compile with the limited API are
excluded via the `Py_LIMITED_API` preprocessor macro.

Author: guitargeek

bindings/pyroot/cppyy/CPyCppyy/src/CPPInstance.h

@@ -10,7 +10,9 @@
 //////////////////////////////////////////////////////////////////////////////
 
 // Bindings
+#ifndef Py_LIMITED_API
 #include "CPPScope.h"
+#endif
 #include "Cppyy.h"
 #include "CallContext.h"     // for Parameter
 
@@ -116,12 +118,14 @@ inline void* CPPInstance::GetObject()
 }
 
 //----------------------------------------------------------------------------
+#ifndef Py_LIMITED_API
 inline Cppyy::TCppType_t CPPInstance::ObjectIsA(bool check_smart) const
 {
 // Retrieve the C++ type identifier (or raw type if smart).
     if (check_smart || !IsSmart()) return ((CPPClass*)Py_TYPE(this))->fCppType;
     return GetSmartIsA();
 }
+#endif
 
 
 //- object proxy type and type verification ----------------------------------
@@ -132,6 +136,7 @@ extern __declspec(dllimport) PyTypeObject CPPInstance_Type;
 extern PyTypeObject CPPInstance_Type;
 #endif
 
+#ifndef Py_LIMITED_API
 template<typename T>
 inline bool CPPInstance_Check(T* object)
 {
@@ -141,6 +146,7 @@ inline bool CPPInstance_Check(T* object)
         (Py_TYPE(object)->tp_new == CPPInstance_Type.tp_new || \
          PyObject_TypeCheck(object, &CPPInstance_Type));
 }
+#endif
 
 template<typename T>
 inline bool CPPInstance_CheckExact(T* object)

bindings/pyroot/cppyy/CPyCppyy/src/CPyCppyyModule.cxx

@@ -35,6 +35,12 @@ PyObject* Instance_FromVoidPtr(
 #include <utility>
 #include <vector>
 
+#if PY_VERSION_HEX < 0x030b0000
+namespace CPyCppyy {
+extern dict_lookup_func gDictLookupOrg;
+dict_lookup_func gDictLookupOrg = nullptr;
+} // namespace CPyCppyy
+#endif
 
 // Note: as of py3.11, dictionary objects no longer carry a function pointer for
 // the lookup, so it can no longer be shimmed and "from cppyy.interactive import *"

bindings/pyroot/cppyy/CPyCppyy/src/Dimensions.h

@@ -1,6 +1,9 @@
 #ifndef CPYCPPYY_DIMENSIONS_H
 #define CPYCPPYY_DIMENSIONS_H
 
+// Bindings
+#include "CPyCppyy/CommonDefs.h"
+
 // Standard
 #include <algorithm>
 #include <initializer_list>

bindings/pyroot/cppyy/CPyCppyy/src/Utility.cxx

@@ -24,7 +24,6 @@
 
 //- data _____________________________________________________________________
 #if PY_VERSION_HEX < 0x030b0000
-dict_lookup_func CPyCppyy::gDictLookupOrg = 0;
 bool CPyCppyy::gDictLookupActive = false;
 #endif
 

bindings/pyroot/cppyy/CPyCppyy/src/Utility.h

@@ -13,7 +13,6 @@ namespace CPyCppyy {
 class PyCallable;
 
 #if PY_VERSION_HEX < 0x030b0000
-extern dict_lookup_func gDictLookupOrg;
 extern bool gDictLookupActive;
 #endif
 
@@ -46,7 +45,11 @@ inline PyObject* CT2CppName(PyObject* pytc, const char* cpd, bool allow_voidp)
     const std::string& name = CT2CppNameS(pytc, allow_voidp);
     if (!name.empty()) {
         if (name == "const char*") cpd = "";
-        return CPyCppyy_PyText_FromString((std::string{name}+cpd).c_str());
+#if PY_VERSION_HEX < 0x03000000
+        return PyString_FromString((std::string{name}+cpd).c_str());
+#else
+        return PyUnicode_FromString((std::string{name}+cpd).c_str());
+#endif
     }
     return nullptr;
 }

bindings/pyroot/pythonizations/CMakeLists.txt

@@ -31,6 +31,17 @@ set(libname ROOTPythonizations)
 
 add_library(${libname} SHARED ${cpp_sources})
 
+# Use what is in the limited API since Python 3.11, if we build with a lower
+# Python version, we don't bother using the limited API.
+if (Python3_VERSION VERSION_GREATER_EQUAL "3.11")
+  # On Windows we can't use the stable ABI yet: it requires linking against a
+  # different libpython, so as long as we don't build all translation units in
+  # the ROOT Pythonization library with the stable ABI we should not use it.
+  if(NOT MSVC)
+    target_compile_options(${libname} PRIVATE -DPy_LIMITED_API=0x030B0000)
+  endif()
+endif()
+
 # Set the suffix to '.so' and the prefix to 'lib'
 set_target_properties(${libname} PROPERTIES ${ROOT_LIBRARY_PROPERTIES_NO_VERSION})
 target_link_libraries(${libname} PUBLIC Core Tree CPyCppyy)

bindings/pyroot/pythonizations/src/CPPInstancePyz.cxx

@@ -9,7 +9,7 @@
  * For the list of contributors see $ROOTSYS/README/CREDITS.             *
  *************************************************************************/
 
-#include "PythonLimitedAPI.h"
+#include <Python.h>
 
 // Bindings
 #include "CPyCppyy/API.h"

bindings/pyroot/pythonizations/src/GenericPyz.cxx

@@ -13,7 +13,7 @@
 
 #include "CPyCppyy/API.h"
 
-#include "../../cppyy/CPyCppyy/src/CPyCppyy.h"
+#include "../../cppyy/CPyCppyy/src/Cppyy.h"
 #include "../../cppyy/CPyCppyy/src/Utility.h"
 
 #include "PyROOTPythonize.h"

bindings/pyroot/pythonizations/src/IOHandler.cxx

@@ -8,7 +8,7 @@
  * For the list of contributors see $ROOTSYS/README/CREDITS.             *
  *************************************************************************/
 
-#include "PythonLimitedAPI.h"
+#include <Python.h>
 
 #include <fcntl.h>
 #ifdef _MSC_VER // Visual Studio

bindings/pyroot/pythonizations/src/PyROOTPythonize.h

@@ -12,7 +12,7 @@
 #ifndef PYROOT_PYTHONIZE_H
 #define PYROOT_PYTHONIZE_H
 
-#include "PythonLimitedAPI.h"
+#include <Python.h>
 
 namespace PyROOT {