Converters.cxx

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// Bindings
#include "cpyrt.h"
 
using namespace cppjit;
#include "CPPExcInstance.h"
#include "CPPInstance.h"
#include "CPPOverload.h"
#include "CallContext.h"
#include "CustomPyTypes.h"
#include "DeclareConverters.h"
#include "LowLevelViews.h"
#include "MemoryRegulator.h"
#include "ProxyWrappers.h"
#include "PyStrings.h"
#include "TemplateProxy.h"
#include "TupleOfInstances.h"
#include "TypeManip.h"
#include "Utility.h"
#include "cppjit_interop.h"
 
// Standard
#include <algorithm>
#include <array>
#include <cassert>
#include <complex>
#include <cstddef>
#include <limits.h>
#include <locale> // for wstring_convert
#include <regex>
#include <sstream>
#include <stddef.h> // for ptrdiff_t
#include <string.h>
#include <string_view>
#include <utility>
#include <vector>
#if __cplusplus >= 202002L
#include <span>
#endif
 
//- data _____________________________________________________________________
namespace cppjit::cpyrt {
 
// factories
typedef std::unordered_map<std::string, cf_t> ConvFactories_t;
static ConvFactories_t gConvFactories;
 
// special objects
extern PyObject* gNullPtrObject;
extern PyObject* gDefaultObject;
} // namespace cppjit::cpyrt
 
// Define our own PyUnstable_Object_IsUniqueReferencedTemporary function if the
// Python version is lower than 3.14, the version where that function got
// introduced.
#if PY_VERSION_HEX < 0x030e0000
const Py_ssize_t MOVE_REFCOUNT_CUTOFF = 1;
inline bool PyUnstable_Object_IsUniqueReferencedTemporary(PyObject* pyobject) {
  return Py_REFCNT(pyobject) <= MOVE_REFCOUNT_CUTOFF;
}
#endif
 
//- pretend-ctypes helpers ---------------------------------------------------
struct cpyrt_tagCDataObject { // non-public (but stable)
  PyObject_HEAD char* b_ptr;
  int b_needsfree;
};
 
struct cpyrt_tagPyCArgObject { // not public (but stable; note that older
  PyObject_HEAD                // Pythons protect 'D' with HAVE_LONG_LONG)
      void* pffi_type;
  char tag;
  union { // for convenience, kept only relevant vals
    char c;
    char b;
    short h;
    int i;
    long l;
    long long q;
    long double g;
    void* p;
#if PY_VERSION_HEX >= 0x030e0000
    double D[2];
    float F[2];
    long double G[2];
#endif
  } value;
  PyObject* obj;
#if PY_VERSION_HEX >= 0x030e0000
  Py_ssize_t size;
#endif
};
 
// indices of ctypes types into the array caches (note that c_complex and
// c_fcomplex do not exist as types in ctypes)
#define ct_c_bool 0
#define ct_c_char 1
#define ct_c_shar 1
#define ct_c_wchar 2
#define ct_c_byte 3
#define ct_c_int8 3
#define ct_c_ubyte 4
#define ct_c_uchar 4
#define ct_c_uint8 4
#define ct_c_short 5
#define ct_c_ushort 6
#define ct_c_uint16 7
#define ct_c_int 8
#define ct_c_uint 9
#define ct_c_uint32 10
#define ct_c_long 11
#define ct_c_ulong 12
#define ct_c_longlong 13
#define ct_c_ulonglong 14
#define ct_c_float 15
#define ct_c_double 16
#define ct_c_longdouble 17
#define ct_c_char_p 18
#define ct_c_wchar_p 19
#define ct_c_void_p 20
#define ct_c_fcomplex 21
#define ct_c_complex 22
#define ct_c_pointer 23
#define ct_c_funcptr 24
#define ct_c_int16 25
#define ct_c_int32 26
#define NTYPES 27
 
static std::array<const char*, NTYPES> gCTypesNames = {
    "c_bool",   "c_char",     "c_wchar",      "c_byte",     "c_ubyte",
    "c_short",  "c_ushort",   "c_uint16",     "c_int",      "c_uint",
    "c_uint32", "c_long",     "c_ulong",      "c_longlong", "c_ulonglong",
    "c_float",  "c_double",   "c_longdouble", "c_char_p",   "c_wchar_p",
    "c_void_p", "c_fcomplex", "c_complex",    "_Pointer",   "_CFuncPtr",
    "c_int16",  "c_int32"};
static std::array<PyTypeObject*, NTYPES> gCTypesTypes;
static std::array<PyTypeObject*, NTYPES> gCTypesPtrTypes;
 
// Both GetCTypesType and GetCTypesPtrType, rely on the ctypes module itself
// caching the types (thus also making them unique), so no ref-count is needed.
// Further, by keeping a ref-count on the module, it won't be off-loaded until
// the 2nd cleanup cycle.
static PyTypeObject* GetCTypesType(int nidx) {
  static PyObject* ctmod = PyImport_ImportModule("ctypes"); // ref-count kept
  if (!ctmod) {
    PyErr_Clear();
    return nullptr;
  }
  PyTypeObject* ct_t = gCTypesTypes[nidx];
  if (!ct_t) {
    ct_t = (PyTypeObject*)PyObject_GetAttrString(ctmod, gCTypesNames[nidx]);
    if (!ct_t)
      PyErr_Clear();
    else {
      gCTypesTypes[nidx] = ct_t;
      Py_DECREF(ct_t);
    }
  }
  return ct_t;
}
 
static PyTypeObject* GetCTypesPtrType(int nidx) {
  static PyObject* ctmod = PyImport_ImportModule("ctypes"); // ref-count kept
  if (!ctmod) {
    PyErr_Clear();
    return nullptr;
  }
  PyTypeObject* cpt_t = gCTypesPtrTypes[nidx];
  if (!cpt_t) {
    if (strcmp(gCTypesNames[nidx], "c_char") == 0) {
      cpt_t = (PyTypeObject*)PyObject_GetAttrString(ctmod, "c_char_p");
    } else {
      PyObject* ct_t = (PyObject*)GetCTypesType(nidx);
      if (ct_t) {
        PyObject* ptrcreat = PyObject_GetAttrString(ctmod, "POINTER");
        cpt_t =
            (PyTypeObject*)PyObject_CallFunctionObjArgs(ptrcreat, ct_t, NULL);
        Py_DECREF(ptrcreat);
      }
    }
    if (cpt_t) {
      gCTypesPtrTypes[nidx] = cpt_t;
      Py_DECREF(cpt_t);
    }
  }
  return cpt_t;
}
 
static bool IsPyCArgObject(PyObject* pyobject) {
  static PyTypeObject* pycarg_type = nullptr;
  if (!pycarg_type) {
    PyObject* ctmod = PyImport_ImportModule("ctypes");
    if (!ctmod)
      PyErr_Clear();
    else {
      PyTypeObject* ct_t =
          (PyTypeObject*)PyObject_GetAttrString(ctmod, "c_int");
      PyObject* cobj = ct_t->tp_new(ct_t, nullptr, nullptr);
      PyObject* byref = PyObject_GetAttrString(ctmod, "byref");
      PyObject* pyptr = PyObject_CallFunctionObjArgs(byref, cobj, NULL);
      Py_DECREF(byref);
      Py_DECREF(cobj);
      Py_DECREF(ct_t);
      pycarg_type = Py_TYPE(pyptr); // static, no ref-count needed
      Py_DECREF(pyptr);
      Py_DECREF(ctmod);
    }
  }
  return Py_TYPE(pyobject) == pycarg_type;
}
 
#if PY_VERSION_HEX < 0x30d0000
static bool IsCTypesArrayOrPointer(PyObject* pyobject) {
  static PyTypeObject* cstgdict_type = nullptr;
  if (!cstgdict_type) {
    // get any pointer type to initialize the extended dictionary type
    PyTypeObject* ct_int = GetCTypesType(ct_c_int);
    if (ct_int && ct_int->tp_dict) {
      cstgdict_type = Py_TYPE(ct_int->tp_dict);
    }
  }
 
  PyTypeObject* pytype = Py_TYPE(pyobject);
  if (pytype->tp_dict && Py_TYPE(pytype->tp_dict) == cstgdict_type)
    return true;
  return false;
}
#else
// the internals of ctypes have been redone, requiring a more complex checking
namespace {
 
typedef struct {
  PyTypeObject* DictRemover_Type;
  PyTypeObject* PyCArg_Type;
  PyTypeObject* PyCField_Type;
  PyTypeObject* PyCThunk_Type;
  PyTypeObject* StructParam_Type;
  PyTypeObject* PyCType_Type;
  PyTypeObject* PyCStructType_Type;
  PyTypeObject* UnionType_Type;
  PyTypeObject* PyCPointerType_Type;
  // ... unused fields omitted ...
} _cppjit_ctypes_state;
 
} // unnamed namespace
 
static bool IsCTypesArrayOrPointer(PyObject* pyobject) {
  static _cppjit_ctypes_state* state = nullptr;
  if (!state) {
    PyObject* ctmod = PyImport_AddModule(
        "_ctypes"); // the extension module, not the Python one
    if (ctmod)
      state = (_cppjit_ctypes_state*)PyModule_GetState(ctmod);
  }
 
  // verify for object types that have a C payload
  if (state && (PyObject_IsInstance((PyObject*)Py_TYPE(pyobject),
                                    (PyObject*)state->PyCType_Type) ||
                PyObject_IsInstance((PyObject*)Py_TYPE(pyobject),
                                    (PyObject*)state->PyCPointerType_Type))) {
    return true;
  }
 
  return false;
}
#endif
 
//- helper to establish life lines -------------------------------------------
static inline bool SetLifeLine(PyObject* holder, PyObject* target,
                               intptr_t ref) {
  // set a lifeline from on the holder to the target, using the ref as label
  if (!holder)
    return false;
 
  // 'ref' is expected to be the converter address or data memory location, so
  // that the combination of holder and ref is unique, but also identifiable for
  // reuse when the C++ side is being overwritten
  std::ostringstream attr_name;
  attr_name << "__" << ref;
  auto res =
      PyObject_SetAttrString(holder, (char*)attr_name.str().c_str(), target);
  return res != -1;
}
 
static bool HasLifeLine(PyObject* holder, intptr_t ref) {
  // determine if a lifeline was previously set for the ref on the holder
  if (!holder)
    return false;
 
  std::ostringstream attr_name;
  attr_name << "__" << ref;
  PyObject* res =
      PyObject_GetAttrString(holder, (char*)attr_name.str().c_str());
 
  if (res) {
    Py_DECREF(res);
    return true;
  }
 
  PyErr_Clear();
  return false;
}
 
//- helper to work with both CPPInstance and CPPExcInstance ------------------
static inline cpyrt::CPPInstance*
GetCppInstance(PyObject* pyobject,
               interop::TCppScope_t klass = interop::TCppScope_t{},
               bool accept_rvalue = false) {
  using namespace cppjit::cpyrt;
  if (CPPInstance_Check(pyobject))
    return (CPPInstance*)pyobject;
  if (CPPExcInstance_Check(pyobject))
    return (CPPInstance*)((CPPExcInstance*)pyobject)->fCppInstance;
 
  // this is not a C++ proxy; allow custom cast to C++
  PyObject* castobj = PyObject_CallMethodNoArgs(pyobject, PyStrings::gCastCpp);
  if (castobj) {
    if (CPPInstance_Check(castobj))
      return (CPPInstance*)castobj;
    else if (klass && PyTuple_CheckExact(castobj)) {
      // allow implicit conversion from a tuple of arguments
      PyObject* pyclass = GetScopeProxy(klass);
      if (pyclass) {
        CPPInstance* pytmp =
            (CPPInstance*)PyObject_Call(pyclass, castobj, NULL);
        Py_DECREF(pyclass);
        if (CPPInstance_Check(pytmp)) {
          if (accept_rvalue)
            pytmp->fFlags |= CPPInstance::kIsRValue;
          Py_DECREF(castobj);
          return pytmp;
        }
        Py_XDECREF(pytmp);
      }
    }
 
    Py_DECREF(castobj);
    return nullptr;
  }
 
  PyErr_Clear();
  return nullptr;
}
 
//- custom helpers to check ranges -------------------------------------------
static inline bool IsCPPEnumInstance(PyObject* pyobject) {
  // cppjit enums are int subclasses created with __underlying on the class
  if (!PyLong_Check(pyobject) || PyLong_CheckExact(pyobject) ||
      PyBool_Check(pyobject))
    return false;
  return PyObject_HasAttr((PyObject*)Py_TYPE(pyobject),
                          cppjit::cpyrt::PyStrings::gUnderlying);
}
 
// bools and enum instances match integer parameters in the implicit round
// only; a nested call under kNoImplicit is that round (an implicit
// construction from the argument), so enum instances pass there
static inline bool ImplicitBool(PyObject* pyobject, cpyrt::CallContext* ctxt) {
  using namespace cppjit::cpyrt;
  if (!AllowImplicit(ctxt) &&
      (PyBool_Check(pyobject) ||
       (IsCPPEnumInstance(pyobject) && !NoImplicit(ctxt)))) {
    if (!NoImplicit(ctxt))
      ctxt->fFlags |= CallContext::kHaveImplicit;
    return false;
  }
  return true;
}
 
static inline bool StrictBool(PyObject* pyobject, cpyrt::CallContext* ctxt) {
  using namespace cppjit::cpyrt;
  if (!AllowImplicit(ctxt) && !PyBool_Check(pyobject)) {
    if (!NoImplicit(ctxt))
      ctxt->fFlags |= CallContext::kHaveImplicit;
    return false;
  }
  return true;
}
 
static inline bool cpyrt_PyLong_AsBool(PyObject* pyobject) {
  // range-checking python integer to C++ bool conversion
  long l = PyLong_AsLong(pyobject);
  // fail to pass float -> bool; the problem is rounding (0.1 -> 0 -> False)
  if (!(l == 0 || l == 1) || PyFloat_Check(pyobject)) {
    PyErr_SetString(PyExc_ValueError,
                    "boolean value should be bool, or integer 1 or 0");
    return (bool)-1;
  }
  return (bool)l;
}
 
// range-checking python integer to C++ integer conversion (prevents p2.7 silent
// conversions)
#define CPPJIT_PYLONG_AS_TYPE(name, type, limit_low, limit_high)               \
  static inline type cpyrt_PyLong_As##name(PyObject* pyobject) {               \
    if (!PyLong_Check(pyobject)) {                                             \
      if (pyobject == cpyrt::gDefaultObject)                                   \
        return (type)0;                                                        \
      PyErr_SetString(PyExc_TypeError,                                         \
                      #type " conversion expects an integer object");          \
      return (type) - 1;                                                       \
    }                                                                          \
    long l = PyLong_AsLong(pyobject);                                          \
    if (l < limit_low || limit_high < l) {                                     \
      PyErr_Format(PyExc_ValueError, "integer %ld out of range for " #type,    \
                   l);                                                         \
      return (type) - 1;                                                       \
    }                                                                          \
    return (type)l;                                                            \
  }
 
CPPJIT_PYLONG_AS_TYPE(UInt8, uint8_t, 0, UCHAR_MAX)
CPPJIT_PYLONG_AS_TYPE(Int8, int8_t, SCHAR_MIN, SCHAR_MAX)
CPPJIT_PYLONG_AS_TYPE(UInt16, uint16_t, 0, UINT16_MAX)
CPPJIT_PYLONG_AS_TYPE(Int16, int16_t, INT16_MIN, INT16_MAX)
CPPJIT_PYLONG_AS_TYPE(UInt32, uint32_t, 0, UINT32_MAX)
CPPJIT_PYLONG_AS_TYPE(Int32, int32_t, INT32_MIN, INT32_MAX)
CPPJIT_PYLONG_AS_TYPE(UShort, unsigned short, 0, USHRT_MAX)
CPPJIT_PYLONG_AS_TYPE(Short, short, SHRT_MIN, SHRT_MAX)
CPPJIT_PYLONG_AS_TYPE(StrictInt, int, INT_MIN, INT_MAX)
 
static inline long cpyrt_PyLong_AsStrictLong(PyObject* pyobject) {
  // strict python integer to C++ long integer conversion
 
  // prevent float -> long (see cpyrt_PyLong_AsStrictInt)
  if (!PyLong_Check(pyobject)) {
    if (pyobject == cpyrt::gDefaultObject)
      return (long)0;
    PyErr_SetString(PyExc_TypeError,
                    "int/long conversion expects an integer object");
    return (long)-1;
  }
 
  return (long)PyLong_AsLong(pyobject); // already does long range check
}
 
static inline PY_LONG_LONG cpyrt_PyLong_AsStrictLongLong(PyObject* pyobject) {
  // strict python integer to C++ long long integer conversion
 
  // prevent float -> long (see cpyrt_PyLong_AsStrictInt)
  if (!PyLong_Check(pyobject)) {
    if (pyobject == cpyrt::gDefaultObject)
      return (PY_LONG_LONG)0;
    PyErr_SetString(PyExc_TypeError,
                    "int/long conversion expects an integer object");
    return (PY_LONG_LONG)-1;
  }
 
  return PyLong_AsLongLong(pyobject); // already does long range check
}
 
//- helper for pointer/array/reference conversions ---------------------------
static inline bool CArraySetArg(PyObject* pyobject, cpyrt::Parameter& para,
                                char tc, int size, bool check = true) {
  // Case of LowLevelView. In general, they also implement the buffer protocol,
  // but for views around nullptr or C-style arrays without size info the buffer
  // protocol implementation is incomplete and PyObject_GetBuffer will fail.
  if (cpyrt::LowLevelView_Check(pyobject)) {
    auto llview = ((cpyrt::LowLevelView*)pyobject);
    if (llview->fBufInfo.itemsize != size ||
        !strchr(llview->fBufInfo.format, tc)) {
      PyErr_Format(PyExc_TypeError,
                   "could not convert argument to buffer or nullptr");
      return false;
    }
 
    para.fValue.fVoidp = llview->get_buf();
  }
  // general case of loading a C array pointer (void* + type code) as function
  // argument
  else if (pyobject == cpyrt::gNullPtrObject ||
           pyobject == cpyrt::gDefaultObject)
    para.fValue.fVoidp = nullptr;
  else {
    Py_ssize_t buflen = cpyrt::Utility::GetBuffer(pyobject, tc, size,
                                                  para.fValue.fVoidp, check);
    if (!buflen) {
      // stuck here as it's the least common
      if (cpyrt_PyLong_AsStrictInt(pyobject) == 0)
        para.fValue.fVoidp = nullptr;
      else {
        PyErr_Format(PyExc_TypeError, // ValueError?
                     "could not convert argument to buffer or nullptr");
        return false;
      }
    }
  }
  para.fTypeCode = 'p';
  return true;
}
 
//- helper for implicit conversions ------------------------------------------
static inline cpyrt::CPPInstance* ConvertImplicit(interop::TCppScope_t klass,
                                                  PyObject* pyobject,
                                                  cpyrt::Parameter& para,
                                                  cpyrt::CallContext* ctxt,
                                                  bool manage = true) {
  using namespace cppjit::cpyrt;
 
  // filter out copy and move constructors
  if (IsConstructor(ctxt->fFlags) && klass == ctxt->fCurScope &&
      ctxt->GetSize() == 1)
    return nullptr;
 
  // never attempt implicit conversion to standard library implementation
  // details (leading underscore, e.g. MSVC's std::_Swc_base, the base of its
  // random engines, which has an unconstrained generator constructor that
  // accepts anything): no user-facing API expects them, and every failed
  // attempt JIT-compiles a constructor wrapper, which is prohibitively slow
  // when it happens per call in overload resolution (seen as pyunittests
  // timeouts on the Windows CI). The one legitimate case is a conversion
  // between instantiations of the _same_ implementation-detail template,
  // e.g. libc++'s iterator to const_iterator (std::__wrap_iter<char*> to
  // std::__wrap_iter<const char*>), which uses a converting constructor.
  {
    const std::string& clName = interop::GetScopedFinalName(klass);
    if (clName.compare(0, 6, "std::_") == 0 ||
        (!clName.empty() && clName[0] == '_')) {
      bool sameTemplate = false;
      if (CPPInstance_Check(pyobject)) {
        interop::TCppScope_t src = ((CPPInstance*)pyobject)->ObjectIsA();
        if (src && src != klass) {
          const std::string& srcName = interop::GetScopedFinalName(src);
          std::string::size_type lt = clName.find('<');
          sameTemplate = lt != std::string::npos && srcName.size() > lt &&
                         srcName[lt] == '<' &&
                         srcName.compare(0, lt, clName, 0, lt) == 0;
        }
      }
      if (!sameTemplate)
        return nullptr;
    }
  }
 
  // only proceed if implicit conversions are allowed (in "round 2") or if the
  // argument is exactly a tuple or list, as these are the equivalent of
  // initializer lists and thus "syntax" not a conversion
  if (!AllowImplicit(ctxt)) {
    PyTypeObject* pytype = (PyTypeObject*)Py_TYPE(pyobject);
    if (!(pytype == &PyList_Type ||
          pytype == &PyTuple_Type)) { // || !CPPInstance_Check(pyobject))) {
      if (!NoImplicit(ctxt))
        ctxt->fFlags |= CallContext::kHaveImplicit;
      return nullptr;
    }
  }
 
  // exercise implicit conversion
  PyObject* pyscope = CreateScopeProxy(klass);
  if (!CPPScope_Check(pyscope)) {
    Py_XDECREF(pyscope);
    return nullptr;
  }
 
  // call constructor of argument type to attempt implicit conversion (disallow
  // any implicit conversions by the scope's constructor itself)
  PyObject* args = PyTuple_New(1);
  Py_INCREF(pyobject);
  PyTuple_SET_ITEM(args, 0, pyobject);
 
  ((CPPScope*)pyscope)->fFlags |= CPPScope::kActiveImplicitCall;
  CPPInstance* pytmp = (CPPInstance*)PyObject_Call(pyscope, args, NULL);
  if (!pytmp && PyTuple_CheckExact(pyobject)) {
    // special case: allow implicit conversion from given set of arguments in
    // tuple
    PyErr_Clear();
    pytmp = (CPPInstance*)PyObject_Call(pyscope, pyobject, NULL);
  }
  ((CPPScope*)pyscope)->fFlags &= ~CPPScope::kActiveImplicitCall;
 
  Py_DECREF(args);
  Py_DECREF(pyscope);
 
  if (pytmp) {
    // implicit conversion succeeded!
    if (manage)
      ctxt->AddTemporary((PyObject*)pytmp);
    para.fValue.fVoidp = pytmp->GetObjectRaw();
    para.fTypeCode = 'V';
    return pytmp;
  }
 
  PyErr_Clear();
  return nullptr;
}
 
//- base converter implementation --------------------------------------------
cppjit::cpyrt::Converter::~Converter() { /* empty */ }
 
//----------------------------------------------------------------------------
PyObject* cppjit::cpyrt::Converter::FromMemory(void*) {
  // could happen if no derived class override
  PyErr_SetString(PyExc_TypeError, "C++ type cannot be converted from memory");
  return nullptr;
}
 
//----------------------------------------------------------------------------
bool cppjit::cpyrt::Converter::ToMemory(PyObject*, void*,
                                        PyObject* /* ctxt */) {
  // could happen if no derived class override
  PyErr_SetString(PyExc_TypeError, "C++ type cannot be converted to memory");
  return false;
}
 
//- helper macro's -----------------------------------------------------------
#define CPPJIT_IMPL_BASIC_CONVERTER_BODY(name, type, stype, ctype, F1, F2, tc) \
  /* convert <pyobject> to C++ 'type', set arg for call */                     \
  type val = (type)F2(pyobject);                                               \
  if (val == (type) - 1 && PyErr_Occurred()) {                                 \
    static PyTypeObject* ctypes_type = nullptr;                                \
    if (!ctypes_type) {                                                        \
      auto error = cpyrt::Utility::FetchPyError();                             \
      ctypes_type = GetCTypesType(ct_##ctype);                                 \
      cpyrt::Utility::RestorePyError(error);                                   \
    }                                                                          \
    if (Py_TYPE(pyobject) == ctypes_type) {                                    \
      PyErr_Clear();                                                           \
      val = *((type*)((cpyrt_tagCDataObject*)pyobject)->b_ptr);                \
    } else if (pyobject == cpyrt::gDefaultObject) {                            \
      PyErr_Clear();                                                           \
      val = (type)0;                                                           \
    } else                                                                     \
      return false;                                                            \
  }                                                                            \
  para.fValue.f##name = val;                                                   \
  para.fTypeCode = tc;                                                         \
  return true;
 
#define CPPJIT_IMPL_BASIC_CONVERTER_METHODS(name, type, stype, ctype, F1, F2)  \
  PyObject* cpyrt::name##Converter::FromMemory(void* address) {                \
    return F1((stype) * ((type*)address));                                     \
  }                                                                            \
                                                                               \
  bool cpyrt::name##Converter::ToMemory(PyObject* value, void* address,        \
                                        PyObject* /* ctxt */) {                \
    type s = (type)F2(value);                                                  \
    if (s == (type) - 1 && PyErr_Occurred()) {                                 \
      if (value == cpyrt::gDefaultObject) {                                    \
        PyErr_Clear();                                                         \
        s = (type)0;                                                           \
      } else                                                                   \
        return false;                                                          \
    }                                                                          \
    *((type*)address) = (type)s;                                               \
    return true;                                                               \
  }
 
#define CPPJIT_IMPL_BASIC_CONVERTER_NI(name, type, stype, ctype, F1, F2, tc)   \
  bool cpyrt::name##Converter::SetArg(PyObject* pyobject, Parameter& para,     \
                                      CallContext* ctxt) {                     \
    if (!StrictBool(pyobject, ctxt))                                           \
      return false;                                                            \
    CPPJIT_IMPL_BASIC_CONVERTER_BODY(name, type, stype, ctype, F1, F2, tc)     \
  }                                                                            \
  CPPJIT_IMPL_BASIC_CONVERTER_METHODS(name, type, stype, ctype, F1, F2)
 
#define CPPJIT_IMPL_BASIC_CONVERTER_IB(name, type, stype, ctype, F1, F2, tc)   \
  bool cpyrt::name##Converter::SetArg(PyObject* pyobject, Parameter& para,     \
                                      CallContext* ctxt) {                     \
    if (!ImplicitBool(pyobject, ctxt))                                         \
      return false;                                                            \
    CPPJIT_IMPL_BASIC_CONVERTER_BODY(name, type, stype, ctype, F1, F2, tc)     \
  }                                                                            \
  CPPJIT_IMPL_BASIC_CONVERTER_METHODS(name, type, stype, ctype, F1, F2)
 
#define CPPJIT_IMPL_BASIC_CONVERTER_NB(name, type, stype, ctype, F1, F2, tc)   \
  bool cpyrt::name##Converter::SetArg(PyObject* pyobject, Parameter& para,     \
                                      CallContext* /*ctxt*/) {                 \
    if (PyBool_Check(pyobject))                                                \
      return false;                                                            \
    CPPJIT_IMPL_BASIC_CONVERTER_BODY(name, type, stype, ctype, F1, F2, tc)     \
  }                                                                            \
  CPPJIT_IMPL_BASIC_CONVERTER_METHODS(name, type, stype, ctype, F1, F2)
 
//----------------------------------------------------------------------------
static inline int ExtractChar(PyObject* pyobject, const char* tname, int low,
                              int high) {
  int lchar = -1;
  if (PyBytes_Check(pyobject)) {
    if (PyBytes_GET_SIZE(pyobject) == 1)
      lchar = (int)(PyBytes_AsString(pyobject)[0]);
    else
      PyErr_Format(PyExc_ValueError,
                   "%s expected, got bytes of size " PY_SSIZE_T_FORMAT, tname,
                   PyBytes_GET_SIZE(pyobject));
  } else if (PyUnicode_Check(pyobject)) {
    if (PyUnicode_GET_LENGTH(pyobject) == 1)
      lchar = (int)(PyUnicode_AsUTF8(pyobject)[0]);
    else
      PyErr_Format(PyExc_ValueError,
                   "%s expected, got str of size " PY_SSIZE_T_FORMAT, tname,
                   PyUnicode_GET_LENGTH(pyobject));
  } else if (pyobject == cpyrt::gDefaultObject) {
    lchar = (int)'\0';
  } else if (!PyFloat_Check(pyobject)) { // don't allow truncating conversion
    lchar = (int)PyLong_AsLong(pyobject);
    if (lchar == -1 && PyErr_Occurred())
      ; // empty, as error already set
    else if (!(low <= lchar && lchar <= high)) {
      PyErr_Format(PyExc_ValueError,
                   "integer to character: value %d not in range [%d,%d]", lchar,
                   low, high);
      lchar = -1;
    }
  } else
    PyErr_SetString(PyExc_TypeError, "char or small int type expected");
 
  return lchar;
}
 
//----------------------------------------------------------------------------
#define CPPJIT_IMPL_REFCONVERTER_FROM_MEMORY(name, ctype)                      \
  PyObject* cpyrt::name##RefConverter::FromMemory(void* ptr) {                 \
    /* convert a reference to int to Python through ctypes pointer object */   \
    PyTypeObject* ctypes_type = GetCTypesType(ct_##ctype);                     \
    if (!ctypes_type) {                                                        \
      PyErr_SetString(PyExc_RuntimeError, "no ctypes available");              \
      return nullptr;                                                          \
    }                                                                          \
    PyObject* ref = ctypes_type->tp_new(ctypes_type, nullptr, nullptr);        \
    ((cpyrt_tagCDataObject*)ref)->b_ptr = (char*)ptr;                          \
    ((cpyrt_tagCDataObject*)ref)->b_needsfree = 0;                             \
    return ref;                                                                \
  }
 
//----------------------------------------------------------------------------
#define CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(name, type, ctype, F1)            \
  bool cpyrt::Const##name##RefConverter::SetArg(                               \
      PyObject* pyobject, Parameter& para, CallContext* /* ctxt */) {          \
    type val = (type)F1(pyobject);                                             \
    if (val == (type) - 1 && PyErr_Occurred()) {                               \
      if (pyobject == cpyrt::gDefaultObject) {                                 \
        PyErr_Clear();                                                         \
        val = (type)0;                                                         \
      } else                                                                   \
        return false;                                                          \
    }                                                                          \
    para.fValue.f##name = val;                                                 \
    para.fRef = &para.fValue.f##name;                                          \
    para.fTypeCode = 'r';                                                      \
    return true;                                                               \
  }                                                                            \
  CPPJIT_IMPL_REFCONVERTER_FROM_MEMORY(Const##name, ctype)
 
//----------------------------------------------------------------------------
#define CPPJIT_IMPL_BASIC_CONST_CHAR_REFCONVERTER(name, type, ctype, low,      \
                                                  high)                        \
  bool cpyrt::Const##name##RefConverter::SetArg(                               \
      PyObject* pyobject, Parameter& para, CallContext* /* ctxt */) {          \
    /* convert <pyobject> to C++ <<type>>, set arg for call, allow int -> char \
     */                                                                        \
    type val = (type)ExtractChar(pyobject, #type, low, high);                  \
    if (val == (type) - 1 && PyErr_Occurred())                                 \
      return false;                                                            \
    para.fValue.fLong = val;                                                   \
    para.fTypeCode = 'l';                                                      \
    return true;                                                               \
  }                                                                            \
  CPPJIT_IMPL_REFCONVERTER_FROM_MEMORY(Const##name, ctype)
 
//----------------------------------------------------------------------------
#define CPPJIT_IMPL_BASIC_CHAR_CONVERTER(name, type, low, high)                \
  bool cpyrt::name##Converter::SetArg(PyObject* pyobject, Parameter& para,     \
                                      CallContext* /* ctxt */) {               \
    /* convert <pyobject> to C++ <<type>>, set arg for call, allow int -> char \
     */                                                                        \
    long val = ExtractChar(pyobject, #type, low, high);                        \
    if (val == -1 && PyErr_Occurred())                                         \
      return false;                                                            \
    para.fValue.fLong = val;                                                   \
    para.fTypeCode = 'l';                                                      \
    return true;                                                               \
  }                                                                            \
                                                                               \
  PyObject* cpyrt::name##Converter::FromMemory(void* address) {                \
    /* return char in "native" str type as that's more natural in use */       \
    return PyUnicode_FromFormat("%c", *((type*)address));                      \
  }                                                                            \
                                                                               \
  bool cpyrt::name##Converter::ToMemory(PyObject* value, void* address,        \
                                        PyObject* /* ctxt */) {                \
    Py_ssize_t len;                                                            \
    const char* cstr = nullptr;                                                \
    if (PyBytes_Check(value))                                                  \
      PyBytes_AsStringAndSize(value, (char**)&cstr, &len);                     \
    else                                                                       \
      cstr = cpyrt_PyText_AsStringAndSize(value, &len);                        \
    if (cstr) {                                                                \
      if (len != 1) {                                                          \
        PyErr_Format(PyExc_TypeError,                                          \
                     #type " expected, got string of size %zd", len);          \
        return false;                                                          \
      }                                                                        \
      *((type*)address) = (type)cstr[0];                                       \
    } else {                                                                   \
      PyErr_Clear();                                                           \
      long l = PyLong_AsLong(value);                                           \
      if (l == -1 && PyErr_Occurred()) {                                       \
        if (value == cpyrt::gDefaultObject) {                                  \
          PyErr_Clear();                                                       \
          l = (long)0;                                                         \
        } else                                                                 \
          return false;                                                        \
      }                                                                        \
      if (!(low <= l && l <= high)) {                                          \
        PyErr_Format(PyExc_ValueError,                                         \
                     "integer to character: value %ld not in range [%d,%d]",   \
                     l, low, high);                                            \
        return false;                                                          \
      }                                                                        \
      *((type*)address) = (type)l;                                             \
    }                                                                          \
    return true;                                                               \
  }
 
//- converters for built-ins -------------------------------------------------
CPPJIT_IMPL_BASIC_CONVERTER_IB(Long, long, long, c_long, PyLong_FromLong,
                               cpyrt_PyLong_AsStrictLong, 'l')
 
//----------------------------------------------------------------------------
bool cpyrt::LongRefConverter::SetArg(PyObject* pyobject, Parameter& para,
                                     CallContext* /* ctxt */) {
  // convert <pyobject> to C++ long&, set arg for call
 
  if (Py_TYPE(pyobject) == GetCTypesType(ct_c_long)) {
    para.fValue.fVoidp = (void*)((cpyrt_tagCDataObject*)pyobject)->b_ptr;
    para.fTypeCode = 'V';
    return true;
  }
 
  if (CArraySetArg(pyobject, para, 'l', sizeof(long))) {
    para.fTypeCode = 'V';
    return true;
  }
 
  PyErr_SetString(PyExc_TypeError,
                  "use ctypes.c_long for pass-by-ref of longs");
  return false;
}
 
//----------------------------------------------------------------------------
// clang-format off
CPPJIT_IMPL_BASIC_CONST_CHAR_REFCONVERTER(Char,  char,          c_char,  CHAR_MIN,  CHAR_MAX)
CPPJIT_IMPL_BASIC_CONST_CHAR_REFCONVERTER(UChar, unsigned char, c_uchar,        0, UCHAR_MAX)
 
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(Bool,   bool,           c_bool,      cpyrt_PyLong_AsBool)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(Int8,   int8_t,         c_int8,      cpyrt_PyLong_AsInt8)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(UInt8,  uint8_t,        c_uint8,     cpyrt_PyLong_AsUInt8)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(Int16,  int16_t,        c_int16,     cpyrt_PyLong_AsInt16)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(UInt16, uint16_t,       c_uint16,    cpyrt_PyLong_AsUInt16)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(Int32,  int32_t,        c_int32,     cpyrt_PyLong_AsInt32)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(UInt32, uint32_t,       c_uint32,    cpyrt_PyLong_AsUInt32)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(Short,  short,          c_short,     cpyrt_PyLong_AsShort)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(UShort, unsigned short, c_ushort,    cpyrt_PyLong_AsUShort)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(Int,    int,            c_int,       cpyrt_PyLong_AsStrictInt)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(UInt,   unsigned int,   c_uint,      PyLongOrInt_AsULong)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(Long,   long,           c_long,      cpyrt_PyLong_AsStrictLong)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(ULong,  unsigned long,  c_ulong,     PyLongOrInt_AsULong)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(LLong,  PY_LONG_LONG,   c_longlong,  cpyrt_PyLong_AsStrictLongLong)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(ULLong, PY_ULONG_LONG,  c_ulonglong, PyLongOrInt_AsULong64)
// clang-format on
 
//----------------------------------------------------------------------------
bool cpyrt::IntRefConverter::SetArg(PyObject* pyobject, Parameter& para,
                                    CallContext* /* ctxt */) {
  // convert <pyobject> to C++ (pseudo)int&, set arg for call
 
  if (Py_TYPE(pyobject) == GetCTypesType(ct_c_int)) {
    para.fValue.fVoidp = (void*)((cpyrt_tagCDataObject*)pyobject)->b_ptr;
    para.fTypeCode = 'V';
    return true;
  }
 
  // alternate, pass pointer from buffer
  Py_ssize_t buflen =
      Utility::GetBuffer(pyobject, 'i', sizeof(int), para.fValue.fVoidp);
  if (para.fValue.fVoidp && buflen) {
    para.fTypeCode = 'V';
    return true;
  };
 
  PyErr_SetString(PyExc_TypeError, "use ctypes.c_int for pass-by-ref of ints");
  return false;
}
 
//----------------------------------------------------------------------------
#define CPPJIT_IMPL_REFCONVERTER(name, ctype, type, code)                      \
  bool cpyrt::name##RefConverter::SetArg(PyObject* pyobject, Parameter& para,  \
                                         CallContext* /* ctxt */) {            \
    /* convert a reference to int to Python through ctypes pointer object */   \
    if (Py_TYPE(pyobject) == GetCTypesType(ct_##ctype)) {                      \
      para.fValue.fVoidp = (void*)((cpyrt_tagCDataObject*)pyobject)->b_ptr;    \
      para.fTypeCode = 'V';                                                    \
      return true;                                                             \
    }                                                                          \
    bool res = CArraySetArg(pyobject, para, code, sizeof(type));               \
    if (!res) {                                                                \
      PyErr_SetString(PyExc_TypeError,                                         \
                      "use ctypes." #ctype " for pass-by-ref of " #type);      \
      return false;                                                            \
    }                                                                          \
    para.fTypeCode = 'V';                                                      \
    return res;                                                                \
  }                                                                            \
  CPPJIT_IMPL_REFCONVERTER_FROM_MEMORY(name, ctype)
 
// clang-format off
CPPJIT_IMPL_REFCONVERTER(Bool,    c_bool,       bool,               '?');
CPPJIT_IMPL_REFCONVERTER(Char,    c_char,       char,               'b');
CPPJIT_IMPL_REFCONVERTER(WChar,   c_wchar,      wchar_t,            'u');
CPPJIT_IMPL_REFCONVERTER(Char16,  c_uint16,     char16_t,           'H');
CPPJIT_IMPL_REFCONVERTER(Char32,  c_uint32,     char32_t,           'I');
CPPJIT_IMPL_REFCONVERTER(SChar,   c_byte,       signed char,        'b');
CPPJIT_IMPL_REFCONVERTER(UChar,   c_ubyte,      unsigned char,      'B');
CPPJIT_IMPL_REFCONVERTER(Int8,    c_int8,       int8_t,             'b');
CPPJIT_IMPL_REFCONVERTER(UInt8,   c_uint8,      uint8_t,            'B');
CPPJIT_IMPL_REFCONVERTER(Int16,   c_int16,      int16_t,            'h');
CPPJIT_IMPL_REFCONVERTER(UInt16,  c_uint16,     uint16_t,           'H');
CPPJIT_IMPL_REFCONVERTER(Int32,   c_int32,      int32_t,            'i');
CPPJIT_IMPL_REFCONVERTER(UInt32,  c_uint32,     uint32_t,           'I');
CPPJIT_IMPL_REFCONVERTER(Short,   c_short,      short,              'h');
CPPJIT_IMPL_REFCONVERTER(UShort,  c_ushort,     unsigned short,     'H');
CPPJIT_IMPL_REFCONVERTER_FROM_MEMORY(Int, c_int);
CPPJIT_IMPL_REFCONVERTER(UInt,    c_uint,       unsigned int,       'I');
CPPJIT_IMPL_REFCONVERTER_FROM_MEMORY(Long, c_long);
CPPJIT_IMPL_REFCONVERTER(ULong,   c_ulong,      unsigned long,      'L');
CPPJIT_IMPL_REFCONVERTER(LLong,   c_longlong,   long long,          'q');
CPPJIT_IMPL_REFCONVERTER(ULLong,  c_ulonglong,  unsigned long long, 'Q');
CPPJIT_IMPL_REFCONVERTER(Float,   c_float,      float,              'f');
CPPJIT_IMPL_REFCONVERTER_FROM_MEMORY(Double, c_double);
CPPJIT_IMPL_REFCONVERTER(LDouble, c_longdouble, PY_LONG_DOUBLE,     'g');
// clang-format on
 
//----------------------------------------------------------------------------
// convert <pyobject> to C++ bool, allow int/long -> bool, set arg for call
CPPJIT_IMPL_BASIC_CONVERTER_NI(Bool, bool, long, c_bool, PyBool_FromLong,
                               cpyrt_PyLong_AsBool, 'l')
 
//----------------------------------------------------------------------------
CPPJIT_IMPL_BASIC_CHAR_CONVERTER(Char, char, CHAR_MIN, CHAR_MAX)
CPPJIT_IMPL_BASIC_CHAR_CONVERTER(UChar, unsigned char, 0, UCHAR_MAX)
 
PyObject* cpyrt::SCharAsIntConverter::FromMemory(void* address) {
  // special case to be used with arrays: return a Python int instead of str
  // (following the same convention as module array.array)
  return PyLong_FromLong((long)*((signed char*)address));
}
 
PyObject* cpyrt::UCharAsIntConverter::FromMemory(void* address) {
  // special case to be used with arrays: return a Python int instead of str
  // (following the same convention as module array.array)
  return PyLong_FromLong((long)*((unsigned char*)address));
}
 
//----------------------------------------------------------------------------
bool cpyrt::WCharConverter::SetArg(PyObject* pyobject, Parameter& para,
                                   CallContext* /* ctxt */) {
  // convert <pyobject> to C++ <wchar_t>, set arg for call
  if (!PyUnicode_Check(pyobject) || PyUnicode_GET_LENGTH(pyobject) != 1) {
    PyErr_SetString(PyExc_ValueError, "single wchar_t character expected");
    return false;
  }
  wchar_t val;
  Py_ssize_t res = PyUnicode_AsWideChar(pyobject, &val, 1);
  if (res == -1)
    return false;
  para.fValue.fLong = (long)val;
  para.fTypeCode = 'U';
  return true;
}
 
PyObject* cpyrt::WCharConverter::FromMemory(void* address) {
  return PyUnicode_FromWideChar((const wchar_t*)address, 1);
}
 
bool cpyrt::WCharConverter::ToMemory(PyObject* value, void* address,
                                     PyObject* /* ctxt */) {
  if (!PyUnicode_Check(value) || PyUnicode_GET_LENGTH(value) != 1) {
    PyErr_SetString(PyExc_ValueError, "single wchar_t character expected");
    return false;
  }
  wchar_t val;
  Py_ssize_t res = PyUnicode_AsWideChar(value, &val, 1);
  if (res == -1)
    return false;
  *((wchar_t*)address) = val;
  return true;
}
 
//----------------------------------------------------------------------------
bool cpyrt::Char16Converter::SetArg(PyObject* pyobject, Parameter& para,
                                    CallContext* /* ctxt */) {
  // convert <pyobject> to C++ <char16_t>, set arg for call
  if (!PyUnicode_Check(pyobject) || PyUnicode_GET_LENGTH(pyobject) != 1) {
    PyErr_SetString(PyExc_ValueError, "single char16_t character expected");
    return false;
  }
 
  PyObject* bstr = PyUnicode_AsUTF16String(pyobject);
  if (!bstr)
    return false;
 
  char16_t val =
      *(char16_t*)(PyBytes_AS_STRING(bstr) + sizeof(char16_t) /*BOM*/);
  Py_DECREF(bstr);
  para.fValue.fLong = (long)val;
  para.fTypeCode = 'U';
  return true;
}
 
PyObject* cpyrt::Char16Converter::FromMemory(void* address) {
  return PyUnicode_DecodeUTF16((const char*)address, sizeof(char16_t), nullptr,
                               nullptr);
}
 
bool cpyrt::Char16Converter::ToMemory(PyObject* value, void* address,
                                      PyObject* /* ctxt */) {
  if (!PyUnicode_Check(value) || PyUnicode_GET_LENGTH(value) != 1) {
    PyErr_SetString(PyExc_ValueError, "single char16_t character expected");
    return false;
  }
 
  PyObject* bstr = PyUnicode_AsUTF16String(value);
  if (!bstr)
    return false;
 
  *((char16_t*)address) =
      *(char16_t*)(PyBytes_AS_STRING(bstr) + sizeof(char16_t) /*BOM*/);
  Py_DECREF(bstr);
  return true;
}
 
//----------------------------------------------------------------------------
bool cpyrt::Char32Converter::SetArg(PyObject* pyobject, Parameter& para,
                                    CallContext* /* ctxt */) {
  // convert <pyobject> to C++ <char32_t>, set arg for call
  if (!PyUnicode_Check(pyobject) || 2 < PyUnicode_GET_LENGTH(pyobject)) {
    PyErr_SetString(PyExc_ValueError, "single char32_t character expected");
    return false;
  }
 
  PyObject* bstr = PyUnicode_AsUTF32String(pyobject);
  if (!bstr)
    return false;
 
  char32_t val =
      *(char32_t*)(PyBytes_AS_STRING(bstr) + sizeof(char32_t) /*BOM*/);
  Py_DECREF(bstr);
  para.fValue.fLong = (long)val;
  para.fTypeCode = 'U';
  return true;
}
 
PyObject* cpyrt::Char32Converter::FromMemory(void* address) {
  return PyUnicode_DecodeUTF32((const char*)address, sizeof(char32_t), nullptr,
                               nullptr);
}
 
bool cpyrt::Char32Converter::ToMemory(PyObject* value, void* address,
                                      PyObject* /* ctxt */) {
  if (!PyUnicode_Check(value) || 2 < PyUnicode_GET_LENGTH(value)) {
    PyErr_SetString(PyExc_ValueError, "single char32_t character expected");
    return false;
  }
 
  PyObject* bstr = PyUnicode_AsUTF32String(value);
  if (!bstr)
    return false;
 
  *((char32_t*)address) =
      *(char32_t*)(PyBytes_AS_STRING(bstr) + sizeof(char32_t) /*BOM*/);
  Py_DECREF(bstr);
  return true;
}
 
//----------------------------------------------------------------------------
CPPJIT_IMPL_BASIC_CONVERTER_IB(Int8, int8_t, long, c_int8, PyLong_FromLong,
                               cpyrt_PyLong_AsInt8, 'l')
CPPJIT_IMPL_BASIC_CONVERTER_IB(UInt8, uint8_t, long, c_uint8, PyLong_FromLong,
                               cpyrt_PyLong_AsUInt8, 'l')
CPPJIT_IMPL_BASIC_CONVERTER_IB(Int16, int16_t, long, c_int16, PyLong_FromLong,
                               cpyrt_PyLong_AsInt16, 'l')
CPPJIT_IMPL_BASIC_CONVERTER_IB(UInt16, uint16_t, long, c_uint16,
                               PyLong_FromLong, cpyrt_PyLong_AsUInt16, 'l')
CPPJIT_IMPL_BASIC_CONVERTER_IB(Int32, int32_t, long, c_int32, PyLong_FromLong,
                               cpyrt_PyLong_AsInt32, 'l')
CPPJIT_IMPL_BASIC_CONVERTER_IB(UInt32, uint32_t, unsigned long, c_uint32,
                               PyLong_FromUnsignedLong, cpyrt_PyLong_AsUInt32,
                               'l')
CPPJIT_IMPL_BASIC_CONVERTER_IB(Short, short, long, c_short, PyLong_FromLong,
                               cpyrt_PyLong_AsShort, 'l')
CPPJIT_IMPL_BASIC_CONVERTER_IB(UShort, unsigned short, long, c_ushort,
                               PyLong_FromLong, cpyrt_PyLong_AsUShort, 'l')
CPPJIT_IMPL_BASIC_CONVERTER_IB(Int, int, long, c_uint, PyLong_FromLong,
                               cpyrt_PyLong_AsStrictInt, 'l')
 
//----------------------------------------------------------------------------
bool cpyrt::ULongConverter::SetArg(PyObject* pyobject, Parameter& para,
                                   CallContext* ctxt) {
  // convert <pyobject> to C++ unsigned long, set arg for call
  if (!ImplicitBool(pyobject, ctxt))
    return false;
 
  para.fValue.fULong = PyLongOrInt_AsULong(pyobject);
  if (para.fValue.fULong == (unsigned long)-1 && PyErr_Occurred())
    return false;
  para.fTypeCode = 'L';
  return true;
}
 
PyObject* cpyrt::ULongConverter::FromMemory(void* address) {
  // construct python object from C++ unsigned long read at <address>
  return PyLong_FromUnsignedLong(*((unsigned long*)address));
}
 
bool cpyrt::ULongConverter::ToMemory(PyObject* value, void* address,
                                     PyObject* /* ctxt */) {
  // convert <value> to C++ unsigned long, write it at <address>
  unsigned long u = PyLongOrInt_AsULong(value);
  if (u == (unsigned long)-1 && PyErr_Occurred()) {
    if (value == cpyrt::gDefaultObject) {
      PyErr_Clear();
      u = (unsigned long)0;
    } else
      return false;
  }
  *((unsigned long*)address) = u;
  return true;
}
 
//----------------------------------------------------------------------------
PyObject* cpyrt::UIntConverter::FromMemory(void* address) {
  // construct python object from C++ unsigned int read at <address>
  return PyLong_FromUnsignedLong(*((unsigned int*)address));
}
 
bool cpyrt::UIntConverter::ToMemory(PyObject* value, void* address,
                                    PyObject* /* ctxt */) {
  // convert <value> to C++ unsigned int, write it at <address>
  unsigned long u = PyLongOrInt_AsULong(value);
  if (u == (unsigned long)-1 && PyErr_Occurred())
    return false;
 
  if (u > (unsigned long)UINT_MAX) {
    PyErr_SetString(PyExc_OverflowError, "value too large for unsigned int");
    return false;
  }
 
  *((unsigned int*)address) = (unsigned int)u;
  return true;
}
 
//- floating point converters ------------------------------------------------
CPPJIT_IMPL_BASIC_CONVERTER_NB(Float, float, double, c_float,
                               PyFloat_FromDouble, PyFloat_AsDouble, 'f')
CPPJIT_IMPL_BASIC_CONVERTER_NB(Double, double, double, c_double,
                               PyFloat_FromDouble, PyFloat_AsDouble, 'd')
 
CPPJIT_IMPL_BASIC_CONVERTER_NB(LDouble, PY_LONG_DOUBLE, PY_LONG_DOUBLE,
                               c_longdouble, PyFloat_FromDouble,
                               PyFloat_AsDouble, 'g')
 
cpyrt::ComplexDConverter::ComplexDConverter(bool keepControl)
    : InstanceConverter(interop::GetFullScope("std::complex<double>"),
                        keepControl) {}
 
// special case for std::complex<double>, maps it to/from Python's complex
bool cpyrt::ComplexDConverter::SetArg(PyObject* pyobject, Parameter& para,
                                      CallContext* ctxt) {
  const Py_complex& pc = PyComplex_AsCComplex(pyobject);
  if (pc.real != -1.0 || !PyErr_Occurred()) {
    fBuffer.real(pc.real);
    fBuffer.imag(pc.imag);
    para.fValue.fVoidp = &fBuffer;
    para.fTypeCode = 'V';
    return true;
  }
 
  return this->InstanceConverter::SetArg(pyobject, para, ctxt);
}
 
PyObject* cpyrt::ComplexDConverter::FromMemory(void* address) {
  std::complex<double>* dc = (std::complex<double>*)address;
  return PyComplex_FromDoubles(dc->real(), dc->imag());
}
 
bool cpyrt::ComplexDConverter::ToMemory(PyObject* value, void* address,
                                        PyObject* ctxt) {
  const Py_complex& pc = PyComplex_AsCComplex(value);
  if (pc.real != -1.0 || !PyErr_Occurred()) {
    std::complex<double>* dc = (std::complex<double>*)address;
    dc->real(pc.real);
    dc->imag(pc.imag);
    return true;
  }
  return this->InstanceConverter::ToMemory(value, address, ctxt);
}
 
//----------------------------------------------------------------------------
bool cpyrt::DoubleRefConverter::SetArg(PyObject* pyobject, Parameter& para,
                                       CallContext* /* ctxt */) {
  // convert <pyobject> to C++ double&, set arg for call
 
  if (Py_TYPE(pyobject) == GetCTypesType(ct_c_double)) {
    para.fValue.fVoidp = (void*)((cpyrt_tagCDataObject*)pyobject)->b_ptr;
    para.fTypeCode = 'V';
    return true;
  }
 
  // alternate, pass pointer from buffer
  Py_ssize_t buflen =
      Utility::GetBuffer(pyobject, 'd', sizeof(double), para.fValue.fVoidp);
  if (buflen && para.fValue.fVoidp) {
    para.fTypeCode = 'V';
    return true;
  }
 
  PyErr_SetString(PyExc_TypeError,
                  "use ctypes.c_double for pass-by-ref of doubles");
  return false;
}
 
//----------------------------------------------------------------------------
// clang-format off
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(Float,   float,          c_float,      PyFloat_AsDouble)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(Double,  double,         c_double,     PyFloat_AsDouble)
CPPJIT_IMPL_BASIC_CONST_REFCONVERTER(LDouble, PY_LONG_DOUBLE, c_longdouble, PyFloat_AsDouble)
// clang-format on
 
//----------------------------------------------------------------------------
bool cpyrt::VoidConverter::SetArg(PyObject*, Parameter&, CallContext*) {
  // can't happen (unless a type is mapped wrongly), but implemented for
  // completeness
  PyErr_SetString(PyExc_SystemError, "void/unknown arguments can\'t be set");
  return false;
}
 
//----------------------------------------------------------------------------
bool cpyrt::LLongConverter::SetArg(PyObject* pyobject, Parameter& para,
                                   CallContext* ctxt) {
  // convert <pyobject> to C++ long long, set arg for call
  if (!ImplicitBool(pyobject, ctxt))
    return false;
 
  para.fValue.fLLong = cpyrt_PyLong_AsStrictLongLong(pyobject);
  if (PyErr_Occurred())
    return false;
  para.fTypeCode = 'q';
  return true;
}
 
PyObject* cpyrt::LLongConverter::FromMemory(void* address) {
  // construct python object from C++ long long read at <address>
  return PyLong_FromLongLong(*(PY_LONG_LONG*)address);
}
 
bool cpyrt::LLongConverter::ToMemory(PyObject* value, void* address,
                                     PyObject* /* ctxt */) {
  // convert <value> to C++ long long, write it at <address>
  PY_LONG_LONG ll = PyLong_AsLongLong(value);
  if (ll == -1 && PyErr_Occurred()) {
    if (value == cpyrt::gDefaultObject) {
      PyErr_Clear();
      ll = (PY_LONG_LONG)0;
    } else
      return false;
  }
  *((PY_LONG_LONG*)address) = ll;
  return true;
}
 
//----------------------------------------------------------------------------
bool cpyrt::ULLongConverter::SetArg(PyObject* pyobject, Parameter& para,
                                    CallContext* ctxt) {
  // convert <pyobject> to C++ unsigned long long, set arg for call
  if (!ImplicitBool(pyobject, ctxt))
    return false;
 
  para.fValue.fULLong = PyLongOrInt_AsULong64(pyobject);
  if (PyErr_Occurred())
    return false;
  para.fTypeCode = 'Q';
  return true;
}
 
PyObject* cpyrt::ULLongConverter::FromMemory(void* address) {
  // construct python object from C++ unsigned long long read at <address>
  return PyLong_FromUnsignedLongLong(*(PY_ULONG_LONG*)address);
}
 
bool cpyrt::ULLongConverter::ToMemory(PyObject* value, void* address,
                                      PyObject* /* ctxt */) {
  // convert <value> to C++ unsigned long long, write it at <address>
  PY_ULONG_LONG ull = PyLongOrInt_AsULong64(value);
  if (PyErr_Occurred()) {
    if (value == cpyrt::gDefaultObject) {
      PyErr_Clear();
      ull = (PY_ULONG_LONG)0;
    } else
      return false;
  }
  *((PY_ULONG_LONG*)address) = ull;
  return true;
}
 
//----------------------------------------------------------------------------
cpyrt::EnumConverter::~EnumConverter() { DestroyConverter(fBase); }
 
bool cpyrt::EnumConverter::SetArg(PyObject* pyobject, Parameter& para,
                                  CallContext* ctxt) {
  // an instance of the same enum is an exact match; anything else, plain
  // integers included, converts in the implicit round only, as in C++
  if (ctxt && !AllowImplicit(ctxt)) {
    bool exact = false;
    if (IsCPPEnumInstance(pyobject)) {
      PyObject* pycppname =
          PyObject_GetAttr((PyObject*)Py_TYPE(pyobject), PyStrings::gCppName);
      if (pycppname) {
        exact = (fEnumName == PyUnicode_AsUTF8(pycppname));
        Py_DECREF(pycppname);
      } else
        PyErr_Clear();
    }
    if (!exact) {
      if (!NoImplicit(ctxt))
        ctxt->fFlags |= CallContext::kHaveImplicit;
      return false;
    }
    // the base integer converter defers enum instances, so lift the gate
    CallContextRAII<CallContext::kAllowImplicit> allow(ctxt);
    return fBase->SetArg(pyobject, para, ctxt);
  }
  return fBase->SetArg(pyobject, para, ctxt);
}
 
PyObject* cpyrt::EnumConverter::FromMemory(void* address) {
  return fBase->FromMemory(address);
}
 
bool cpyrt::EnumConverter::ToMemory(PyObject* value, void* address,
                                    PyObject* ctxt) {
  return fBase->ToMemory(value, address, ctxt);
}
 
std::string cpyrt::EnumConverter::GetFailureMsg() {
  return fBase->GetFailureMsg();
}
 
//----------------------------------------------------------------------------
bool cpyrt::CStringConverter::SetArg(PyObject* pyobject, Parameter& para,
                                     CallContext* ctxt) {
  // construct a new string and copy it in new memory
  Py_ssize_t len;
  const char* cstr = cpyrt_PyText_AsStringAndSize(pyobject, &len);
  if (!cstr) {
    // special case: allow ctypes c_char_p
    auto error = cpyrt::Utility::FetchPyError();
    if (Py_TYPE(pyobject) == GetCTypesType(ct_c_char_p)) {
      SetLifeLine(ctxt->fPyContext, pyobject, (intptr_t)this);
      para.fValue.fVoidp = (void*)((cpyrt_tagCDataObject*)pyobject)->b_ptr;
      para.fTypeCode = 'V';
      return true;
    }
    cpyrt::Utility::RestorePyError(error);
    return false;
  }
 
  // verify (too long string will cause truncation, no crash)
  if (fMaxSize != std::string::npos && fMaxSize < fBuffer.size())
    if (PyErr_WarnEx(PyExc_RuntimeWarning,
                     (char*)"string too long for char array (truncated)",
                     1) < 0)
      return false;
 
  if (!ctxt->fPyContext) {
    // use internal buffer as workaround
    fBuffer = std::string(cstr, len);
    if (fMaxSize != std::string::npos)
      fBuffer.resize(fMaxSize, '\0'); // pad remainder of buffer as needed
    cstr = fBuffer.c_str();
  } else
    SetLifeLine(ctxt->fPyContext, pyobject, (intptr_t)this);
 
  // set the value and declare success
  para.fValue.fVoidp = (void*)cstr;
  para.fTypeCode = 'p';
  return true;
}
 
PyObject* cpyrt::CStringConverter::FromMemory(void* address) {
  // construct python object from C++ const char* read at <address>
  if (address && *(void**)address) {
    if (fMaxSize !=
        std::string::npos) // need to prevent reading beyond boundary
      return PyUnicode_FromStringAndSize(*(char**)address,
                                         (Py_ssize_t)fMaxSize);
 
    if (*(void**)address ==
        (void*)fBuffer.data()) // if we're buffering, we know the size
      return PyUnicode_FromStringAndSize((char*)fBuffer.data(), fBuffer.size());
 
    // no idea about lentgth: cut on \0
    return PyUnicode_FromString(*(char**)address);
  }
 
  // empty string in case there's no address
  Py_INCREF(PyStrings::gEmptyString);
  return PyStrings::gEmptyString;
}
 
bool cpyrt::CStringConverter::ToMemory(PyObject* value, void* address,
                                       PyObject* ctxt) {
  // convert <value> to C++ const char*, write it at <address>
  Py_ssize_t len;
  const char* cstr = cpyrt_PyText_AsStringAndSize(value, &len);
  if (!cstr)
    return false;
 
  // verify (too long string will cause truncation, no crash)
  if (fMaxSize != std::string::npos && fMaxSize < (std::string::size_type)len)
    if (PyErr_WarnEx(PyExc_RuntimeWarning,
                     (char*)"string too long for char array (truncated)",
                     1) < 0)
      return false;
 
  // if address is available, and it wasn't set by this converter, assume a
  // byte-wise copy; otherwise assume a pointer copy (this relies on the
  // converter to be used for properties, or for argument passing, but not both
  // at the same time; this is currently the case)
  void* ptrval = *(void**)address;
  if (ptrval == (void*)fBuffer.data()) {
    fBuffer = std::string(cstr, len);
    *(void**)address = (void*)fBuffer.data();
    return true;
  } else if (ptrval && HasLifeLine(ctxt, (intptr_t)ptrval)) {
    ptrval = nullptr;
    // fall through; ptrval is nullptr means we're managing it
  }
 
  // the string is (going to be) managed by us: assume pointer copy
  if (!ptrval) {
    SetLifeLine(ctxt, value, (intptr_t)address);
    *(void**)address = (void*)cstr;
    return true;
  }
 
  // the pointer value is non-zero and not ours: assume byte copy
  if (fMaxSize != std::string::npos)
    strncpy(*(char**)address, cstr, fMaxSize); // pads remainder
  else
    // coverity[secure_coding] - can't help it, it's intentional.
    strcpy(*(char**)address, cstr);
 
  return true;
}
 
//----------------------------------------------------------------------------
bool cpyrt::WCStringConverter::SetArg(PyObject* pyobject, Parameter& para,
                                      CallContext* /* ctxt */) {
  // construct a new string and copy it in new memory
  Py_ssize_t len = PyUnicode_GetLength(pyobject);
  if (len == (Py_ssize_t)-1 && PyErr_Occurred())
    return false;
 
  fBuffer = (wchar_t*)realloc(fBuffer, sizeof(wchar_t) * (len + 1));
  Py_ssize_t res = PyUnicode_AsWideChar(pyobject, fBuffer, len);
  if (res == -1)
    return false; // could free the buffer here
 
  // set the value and declare success
  fBuffer[len] = L'\0';
  para.fValue.fVoidp = (void*)fBuffer;
  para.fTypeCode = 'p';
  return true;
}
 
PyObject* cpyrt::WCStringConverter::FromMemory(void* address) {
  // construct python object from C++ wchar_t* read at <address>
  if (address && *(wchar_t**)address) {
    if (fMaxSize !=
        std::wstring::npos) // need to prevent reading beyond boundary
      return PyUnicode_FromWideChar(*(wchar_t**)address, (Py_ssize_t)fMaxSize);
    // with unknown size
    return PyUnicode_FromWideChar(*(wchar_t**)address,
                                  wcslen(*(wchar_t**)address));
  }
 
  // empty string in case there's no valid address
  wchar_t w = L'\0';
  return PyUnicode_FromWideChar(&w, 0);
}
 
bool cpyrt::WCStringConverter::ToMemory(PyObject* value, void* address,
                                        PyObject* /* ctxt */) {
  // convert <value> to C++ wchar_t*, write it at <address>
  Py_ssize_t len = PyUnicode_GetLength(value);
  if (len == (Py_ssize_t)-1 && PyErr_Occurred())
    return false;
 
  // verify (too long string will cause truncation, no crash)
  if (fMaxSize != std::wstring::npos && fMaxSize < (std::wstring::size_type)len)
    if (PyErr_WarnEx(PyExc_RuntimeWarning,
                     (char*)"string too long for wchar_t array (truncated)",
                     1) < 0)
      return false;
 
  Py_ssize_t res = -1;
  if (fMaxSize != std::wstring::npos)
    res =
        PyUnicode_AsWideChar(value, *(wchar_t**)address, (Py_ssize_t)fMaxSize);
  else
    // coverity[secure_coding] - can't help it, it's intentional.
    res = PyUnicode_AsWideChar(value, *(wchar_t**)address, len);
 
  if (res == -1)
    return false;
  return true;
}
 
//----------------------------------------------------------------------------
#define CPYRT_WIDESTRING_CONVERTER(name, type, encode, decode, snull)          \
  bool cpyrt::name##Converter::SetArg(PyObject* pyobject, Parameter& para,     \
                                      CallContext* /* ctxt */) {               \
    /* change string encoding and copy into local buffer */                    \
    PyObject* bstr = encode(pyobject);                                         \
    if (!bstr)                                                                 \
      return false;                                                            \
                                                                               \
    Py_ssize_t len = PyBytes_GET_SIZE(bstr) - sizeof(type) /*BOM*/;            \
    fBuffer = (type*)realloc(fBuffer, len + sizeof(type));                     \
    memcpy(fBuffer, PyBytes_AS_STRING(bstr) + sizeof(type) /*BOM*/, len);      \
    Py_DECREF(bstr);                                                           \
                                                                               \
    fBuffer[len / sizeof(type)] = snull;                                       \
    para.fValue.fVoidp = (void*)fBuffer;                                       \
    para.fTypeCode = 'p';                                                      \
    return true;                                                               \
  }                                                                            \
                                                                               \
  PyObject* cpyrt::name##Converter::FromMemory(void* address) {                \
    /* construct python object from C++ <type>* read at <address> */           \
    if (address && *(type**)address) {                                         \
      if (fMaxSize != std::wstring::npos)                                      \
        return decode(*(const char**)address,                                  \
                      (Py_ssize_t)fMaxSize * sizeof(type), nullptr, nullptr);  \
      return decode(*(const char**)address,                                    \
                    std::char_traits<type>::length(*(type**)address) *         \
                        sizeof(type),                                          \
                    nullptr, nullptr);                                         \
    }                                                                          \
                                                                               \
    /* empty string in case there's no valid address */                        \
    type w = snull;                                                            \
    return decode((const char*)&w, 0, nullptr, nullptr);                       \
  }                                                                            \
                                                                               \
  bool cpyrt::name##Converter::ToMemory(PyObject* value, void* address,        \
                                        PyObject* /* ctxt */) {                \
    /* convert <value> to C++ <type>*, write it at <address> */                \
    PyObject* bstr = encode(value);                                            \
    if (!bstr)                                                                 \
      return false;                                                            \
                                                                               \
    Py_ssize_t len = PyBytes_GET_SIZE(bstr) - sizeof(type) /*BOM*/;            \
    Py_ssize_t maxbytes = (Py_ssize_t)fMaxSize * sizeof(type);                 \
                                                                               \
    /* verify (too long string will cause truncation, no crash) */             \
    if (fMaxSize != std::wstring::npos && maxbytes < len) {                    \
      if (PyErr_WarnEx(PyExc_RuntimeWarning,                                   \
                       (char*)"string too long for " #type                     \
                              " array (truncated)",                            \
                       1) < 0) {                                               \
        Py_DECREF(bstr);                                                       \
        return false;                                                          \
      }                                                                        \
      len = maxbytes;                                                          \
    }                                                                          \
                                                                               \
    memcpy(*((void**)address), PyBytes_AS_STRING(bstr) + sizeof(type) /*BOM*/, \
           len);                                                               \
    Py_DECREF(bstr);                                                           \
    /* debatable, but probably more convenient in most cases to null-terminate \
     * if enough space */                                                      \
    if (len / sizeof(type) < fMaxSize)                                         \
      (*(type**)address)[len / sizeof(type)] = snull;                          \
    return true;                                                               \
  }
 
CPYRT_WIDESTRING_CONVERTER(CString16, char16_t, PyUnicode_AsUTF16String,
                           PyUnicode_DecodeUTF16, u'\0')
CPYRT_WIDESTRING_CONVERTER(CString32, char32_t, PyUnicode_AsUTF32String,
                           PyUnicode_DecodeUTF32, U'\0')
 
//----------------------------------------------------------------------------
bool cpyrt::NonConstCStringConverter::SetArg(PyObject* pyobject,
                                             Parameter& para,
                                             CallContext* ctxt) {
  // attempt base class first (i.e. passing a string), but if that fails, try a
  // buffer
  if (this->CStringConverter::SetArg(pyobject, para, ctxt))
    return true;
 
  // apparently failed, try char buffer
  PyErr_Clear();
  return CArraySetArg(pyobject, para, 'c', sizeof(char));
}
 
//----------------------------------------------------------------------------
PyObject* cpyrt::NonConstCStringConverter::FromMemory(void* address) {
  // assume this is a buffer access if the size is known; otherwise assume
  // string
  if (fMaxSize != std::string::npos)
    return PyUnicode_FromStringAndSize(*(char**)address, (Py_ssize_t)fMaxSize);
  return this->CStringConverter::FromMemory(address);
}
 
//----------------------------------------------------------------------------
bool cpyrt::VoidArrayConverter::GetAddressSpecialCase(PyObject* pyobject,
                                                      void*& address) {
  // (1): C++11 style "null pointer"
  if (pyobject == gNullPtrObject || pyobject == gDefaultObject) {
    address = nullptr;
    return true;
  }
 
  // (2): allow integer zero to act as a null pointer (C NULL), no deriveds
  if (PyLong_CheckExact(pyobject)) {
    intptr_t val = (intptr_t)PyLong_AsLongLong(pyobject);
    if (val == 0l) {
      address = (void*)val;
      return true;
    }
 
    return false;
  }
 
  // (3): opaque PyCapsule (CObject in older pythons) from somewhere
  if (PyCapsule_CheckExact(pyobject)) {
    address = (void*)PyCapsule_GetPointer(pyobject, nullptr);
    return true;
  }
 
  return false;
}
 
//----------------------------------------------------------------------------
bool cpyrt::VoidArrayConverter::SetArg(PyObject* pyobject, Parameter& para,
                                       CallContext* /*ctxt*/) {
  // just convert pointer if it is a C++ object
  CPPInstance* pyobj = GetCppInstance(pyobject);
  para.fValue.fVoidp = nullptr;
  if (pyobj) {
    // depending on memory policy, some objects are no longer owned when passed
    // to C++
    if (!fKeepControl && !UseStrictOwnership())
      pyobj->CppOwns();
 
    // set pointer (may be null) and declare success
    para.fValue.fVoidp = pyobj->GetObject();
    para.fTypeCode = 'p';
    return true;
  }
 
  // handle special cases
  if (GetAddressSpecialCase(pyobject, para.fValue.fVoidp)) {
    para.fTypeCode = 'p';
    return true;
  }
 
  // allow ctypes voidp (which if got as a buffer will return void**, not
  // void*); use isintance instead of an exact check, b/c c_void_p is the type
  // mapper for typedefs of void* (typically opaque handles)
  if (PyObject_IsInstance(pyobject, (PyObject*)GetCTypesType(ct_c_void_p))) {
    para.fValue.fVoidp = (void*)((cpyrt_tagCDataObject*)pyobject)->b_ptr;
    para.fTypeCode = 'V';
    return true;
  }
 
  // allow any other ctypes pointer type
  if (IsCTypesArrayOrPointer(pyobject)) {
    void** payload = (void**)((cpyrt_tagCDataObject*)pyobject)->b_ptr;
    if (payload) {
      para.fValue.fVoidp = *payload;
      para.fTypeCode = 'p';
      return true;
    }
  }
 
  // final try: attempt to get buffer
  Py_ssize_t buflen =
      Utility::GetBuffer(pyobject, '*', 1, para.fValue.fVoidp, false);
 
  // ok if buffer exists (can't perform any useful size checks)
  if (para.fValue.fVoidp && buflen != 0) {
    para.fTypeCode = 'p';
    return true;
  }
 
  // give up
  return false;
}
 
//----------------------------------------------------------------------------
PyObject* cpyrt::VoidArrayConverter::FromMemory(void* address) {
  // nothing sensible can be done, just return <address> as pylong
  if (!address || *(uintptr_t*)address == 0) {
    Py_INCREF(gNullPtrObject);
    return gNullPtrObject;
  }
  return CreatePointerView(*(uintptr_t**)address);
}
 
//----------------------------------------------------------------------------
bool cpyrt::VoidArrayConverter::ToMemory(PyObject* value, void* address,
                                         PyObject* /* ctxt */) {
  // just convert pointer if it is a C++ object
  CPPInstance* pyobj = GetCppInstance(value);
  if (pyobj) {
    // depending on memory policy, some objects are no longer owned when passed
    // to C++
    if (!fKeepControl && !UseStrictOwnership())
      pyobj->CppOwns();
 
    // set pointer (may be null) and declare success
    *(void**)address = pyobj->GetObject();
    return true;
  }
 
  // handle special cases
  void* ptr = nullptr;
  if (GetAddressSpecialCase(value, ptr)) {
    *(void**)address = ptr;
    return true;
  }
 
  // final try: attempt to get buffer
  void* buf = nullptr;
  Py_ssize_t buflen = Utility::GetBuffer(value, '*', 1, buf, false);
  if (!buf || buflen == 0)
    return false;
 
  *(void**)address = buf;
  return true;
}
 
#if __cplusplus >= 202002L
 
namespace cppjit::cpyrt {
 
class StdSpanConverter : public InstanceConverter {
public:
  StdSpanConverter(std::string const& typeName, interop::TCppScope_t klass,
                   bool keepControl = false)
      : InstanceConverter{klass, keepControl}, fTypeName{typeName} {}
 
  ~StdSpanConverter() {
    if (fHasBuffer) {
      PyBuffer_Release(&fBufinfo);
    }
  }
 
  bool SetArg(PyObject*, Parameter&, CallContext* = nullptr) override;
  bool HasState() override { return true; }
 
private:
  std::string fTypeName;
  std::span<std::size_t> fBuffer;
  bool fHasBuffer = false;
  Py_buffer fBufinfo;
};
 
} // namespace cppjit::cpyrt
 
//----------------------------------------------------------------------------
bool cpyrt::StdSpanConverter::SetArg(PyObject* pyobject, Parameter& para,
                                     CallContext* ctxt) {
  auto typecodeFound = Utility::TypecodeMap().find(fTypeName);
 
  // attempt to get buffer if the C++ type maps to a buffer type
  if (typecodeFound == Utility::TypecodeMap().end() ||
      !PyObject_CheckBuffer(pyobject)) {
    // Fall back to regular InstanceConverter
    return this->InstanceConverter::SetArg(pyobject, para, ctxt);
  }
 
  Py_ssize_t buflen = 0;
  char typecode = typecodeFound->second;
  memset(&fBufinfo, 0, sizeof(Py_buffer));
 
  if (PyObject_GetBuffer(pyobject, &fBufinfo, PyBUF_FORMAT) == 0) {
    if (!strchr(fBufinfo.format, typecode)) {
      PyErr_Format(PyExc_TypeError,
                   "buffer has incompatible type: expected '%c' for C++ type "
                   "'%s', but got format '%s'",
                   typecode, fTypeName.c_str(),
                   fBufinfo.format ? fBufinfo.format : "<null>");
      PyBuffer_Release(&fBufinfo);
      return false;
    }
    buflen =
        Utility::GetBuffer(pyobject, typecode, 1, para.fValue.fVoidp, false);
  }
 
  // ok if buffer exists (can't perform any useful size checks)
  if (para.fValue.fVoidp && buflen != 0) {
    // We assume the layout for any std::span<T> is the same, and just use
    // std::span<std::size_t> as a placeholder. Not elegant, but works.
    fBuffer = std::span<std::size_t>{(std::size_t*)para.fValue.fVoidp,
                                     static_cast<std::size_t>(buflen)};
    fHasBuffer = true;
    para.fValue.fVoidp = &fBuffer;
    para.fTypeCode = 'V';
    return true;
  }
 
  return false;
}
 
#endif // __cplusplus >= 202002L
 
namespace {
 
template <class type>
bool ToArrayFromBuffer(PyObject* owner, void* address, PyObject* ctxt,
                       const void* buf, Py_ssize_t buflen, cpyrt::dims_t& shape,
                       bool isFixed) {
  if (buflen == 0)
    return false;
 
  Py_ssize_t oldsz = 1;
  for (Py_ssize_t idim = 0; idim < shape.ndim(); ++idim) {
    if (shape[idim] == cpyrt::UNKNOWN_SIZE) {
      oldsz = -1;
      break;
    }
    oldsz *= shape[idim];
  }
  if (shape.ndim() != cpyrt::UNKNOWN_SIZE && 0 < oldsz && oldsz < buflen) {
    PyErr_SetString(PyExc_ValueError, "buffer too large for value");
    return false;
  }
 
  if (isFixed)
    memcpy(*(type**)address, buf, (0 < buflen ? buflen : 1) * sizeof(type));
  else {
    *(type**)address = (type*)buf;
    shape.ndim(1);
    shape[0] = buflen;
    SetLifeLine(ctxt, owner, (intptr_t)address);
  }
  return true;
}
 
} // namespace
 
//----------------------------------------------------------------------------
#define CPPJIT_IMPL_ARRAY_CONVERTER(name, ctype, type, code, suffix)           \
  cpyrt::name##ArrayConverter::name##ArrayConverter(cdims_t dims)              \
      : fShape(dims) {                                                         \
    fIsFixed = dims ? fShape[0] != UNKNOWN_SIZE : false;                       \
  }                                                                            \
                                                                               \
  bool cpyrt::name##ArrayConverter::SetArg(                                    \
      PyObject* pyobject, Parameter& para, CallContext* ctxt) {                \
    /* filter ctypes first b/c their buffer conversion will be wrong */        \
    bool convOk = false;                                                       \
                                                                               \
    /* 2-dim case: ptr-ptr types */                                            \
    if (!convOk && fShape.ndim() == 2) {                                       \
      if (Py_TYPE(pyobject) == GetCTypesPtrType(ct_##ctype)) {                 \
        para.fValue.fVoidp = (void*)((cpyrt_tagCDataObject*)pyobject)->b_ptr;  \
        para.fTypeCode = 'p';                                                  \
        convOk = true;                                                         \
      } else if (Py_TYPE(pyobject) == GetCTypesType(ct_c_void_p)) {            \
        /* special case: pass address of c_void_p buffer to return the address \
         */                                                                    \
        para.fValue.fVoidp = (void*)((cpyrt_tagCDataObject*)pyobject)->b_ptr;  \
        para.fTypeCode = 'p';                                                  \
        convOk = true;                                                         \
      } else if (LowLevelView_Check(pyobject) &&                               \
                 ((LowLevelView*)pyobject)->fBufInfo.ndim == 2 &&              \
                 strchr(((LowLevelView*)pyobject)->fBufInfo.format, code)) {   \
        para.fValue.fVoidp = ((LowLevelView*)pyobject)->get_buf();             \
        para.fTypeCode = 'p';                                                  \
        convOk = true;                                                         \
      }                                                                        \
    }                                                                          \
                                                                               \
    /* 1-dim (accept pointer), or unknown (accept pointer as cast) */          \
    if (!convOk) {                                                             \
      PyTypeObject* ctypes_type = GetCTypesType(ct_##ctype);                   \
      if (Py_TYPE(pyobject) == ctypes_type) {                                  \
        para.fValue.fVoidp = (void*)((cpyrt_tagCDataObject*)pyobject)->b_ptr;  \
        para.fTypeCode = 'p';                                                  \
        convOk = true;                                                         \
      } else if (Py_TYPE(pyobject) == GetCTypesPtrType(ct_##ctype)) {          \
        para.fValue.fVoidp = (void*)((cpyrt_tagCDataObject*)pyobject)->b_ptr;  \
        para.fTypeCode = 'V';                                                  \
        convOk = true;                                                         \
      } else if (IsPyCArgObject(pyobject)) {                                   \
        cpyrt_tagPyCArgObject* carg = (cpyrt_tagPyCArgObject*)pyobject;        \
        if (carg->obj && Py_TYPE(carg->obj) == ctypes_type) {                  \
          para.fValue.fVoidp =                                                 \
              (void*)((cpyrt_tagCDataObject*)carg->obj)->b_ptr;                \
          para.fTypeCode = 'p';                                                \
          convOk = true;                                                       \
        }                                                                      \
      } else if (LowLevelView_Check(pyobject) &&                               \
                 strchr(((LowLevelView*)pyobject)->fBufInfo.format, code)) {   \
        para.fValue.fVoidp = ((LowLevelView*)pyobject)->get_buf();             \
        para.fTypeCode = 'p';                                                  \
        convOk = true;                                                         \
      }                                                                        \
    }                                                                          \
                                                                               \
    /* cast pointer type */                                                    \
    if (!convOk) {                                                             \
      bool ismulti = fShape.ndim() > 1;                                        \
      convOk = CArraySetArg(pyobject, para, code,                              \
                            ismulti ? sizeof(void*) : sizeof(type), true);     \
    }                                                                          \
                                                                               \
    /* memory management and offsetting */                                     \
    if (convOk)                                                                \
      SetLifeLine(ctxt->fPyContext, pyobject, (intptr_t)this);                 \
                                                                               \
    return convOk;                                                             \
  }                                                                            \
                                                                               \
  PyObject* cpyrt::name##ArrayConverter::FromMemory(void* address) {           \
    if (!fIsFixed)                                                             \
      return CreateLowLevelView##suffix((type**)address, fShape);              \
    return CreateLowLevelView##suffix(*(type**)address, fShape);               \
  }                                                                            \
                                                                               \
  bool cpyrt::name##ArrayConverter::ToMemory(PyObject* value, void* address,   \
                                             PyObject* ctxt) {                 \
    if (fShape.ndim() <= 1 || fIsFixed) {                                      \
      void* buf = nullptr;                                                     \
      Py_ssize_t buflen = Utility::GetBuffer(value, code, sizeof(type), buf);  \
      if (buflen == 0)                                                         \
        return false;                                                          \
                                                                               \
      Py_ssize_t oldsz = 1;                                                    \
      for (Py_ssize_t idim = 0; idim < fShape.ndim(); ++idim) {                \
        if (fShape[idim] == UNKNOWN_SIZE) {                                    \
          oldsz = -1;                                                          \
          break;                                                               \
        }                                                                      \
        oldsz *= fShape[idim];                                                 \
      }                                                                        \
      if (fShape.ndim() != UNKNOWN_SIZE && 0 < oldsz && oldsz < buflen) {      \
        PyErr_SetString(PyExc_ValueError, "buffer too large for value");       \
        return false;                                                          \
      }                                                                        \
                                                                               \
      if (fIsFixed)                                                            \
        memcpy(*(type**)address, buf,                                          \
               (0 < buflen ? buflen : 1) * sizeof(type));                      \
      else {                                                                   \
        *(type**)address = (type*)buf;                                         \
        fShape.ndim(1);                                                        \
        fShape[0] = buflen;                                                    \
        SetLifeLine(ctxt, value, (intptr_t)address);                           \
      }                                                                        \
                                                                               \
    } else { /* multi-dim, non-flat array; assume structure matches */         \
      void* buf = nullptr; /* TODO: GetBuffer() assumes flat? */               \
      Py_ssize_t buflen = Utility::GetBuffer(value, code, sizeof(void*), buf); \
      if (buflen == 0)                                                         \
        return false;                                                          \
      *(type**)address = (type*)buf;                                           \
      SetLifeLine(ctxt, value, (intptr_t)address);                             \
    }                                                                          \
    return true;                                                               \
  }
 
//----------------------------------------------------------------------------
// clang-format off
CPPJIT_IMPL_ARRAY_CONVERTER(Bool,     c_bool,       bool,                 '?', )
CPPJIT_IMPL_ARRAY_CONVERTER(SChar,    c_char,       signed char,          'b', )
CPPJIT_IMPL_ARRAY_CONVERTER(UChar,    c_ubyte,      unsigned char,        'B', )
CPPJIT_IMPL_ARRAY_CONVERTER(Byte,     c_ubyte,      std::byte,            'B', )
CPPJIT_IMPL_ARRAY_CONVERTER(Int8,     c_byte,       int8_t,               'b', _i8)
CPPJIT_IMPL_ARRAY_CONVERTER(Int16,    c_int16,      int16_t,              'h', _i16)
CPPJIT_IMPL_ARRAY_CONVERTER(Int32,    c_int32,      int32_t,              'i', _i32)
CPPJIT_IMPL_ARRAY_CONVERTER(UInt8,    c_ubyte,      uint8_t,              'B', _i8)
CPPJIT_IMPL_ARRAY_CONVERTER(UInt16,   c_uint16,     uint16_t,             'H', _i16)
CPPJIT_IMPL_ARRAY_CONVERTER(UInt32,   c_uint32,     uint32_t,             'I', _i32)
CPPJIT_IMPL_ARRAY_CONVERTER(Short,    c_short,      short,                'h', )
CPPJIT_IMPL_ARRAY_CONVERTER(UShort,   c_ushort,     unsigned short,       'H', )
CPPJIT_IMPL_ARRAY_CONVERTER(Int,      c_int,        int,                  'i', )
CPPJIT_IMPL_ARRAY_CONVERTER(UInt,     c_uint,       unsigned int,         'I', )
CPPJIT_IMPL_ARRAY_CONVERTER(Long,     c_long,       long,                 'l', )
CPPJIT_IMPL_ARRAY_CONVERTER(ULong,    c_ulong,      unsigned long,        'L', )
CPPJIT_IMPL_ARRAY_CONVERTER(LLong,    c_longlong,   long long,            'q', )
CPPJIT_IMPL_ARRAY_CONVERTER(ULLong,   c_ulonglong,  unsigned long long,   'Q', )
CPPJIT_IMPL_ARRAY_CONVERTER(Float,    c_float,      float,                'f', )
CPPJIT_IMPL_ARRAY_CONVERTER(Double,   c_double,     double,               'd', )
CPPJIT_IMPL_ARRAY_CONVERTER(LDouble,  c_longdouble, long double,          'g', )
CPPJIT_IMPL_ARRAY_CONVERTER(ComplexF, c_fcomplex,   std::complex<float>,  'z', )
CPPJIT_IMPL_ARRAY_CONVERTER(ComplexD, c_complex,    std::complex<double>, 'Z', )
// clang-format on
 
//----------------------------------------------------------------------------
bool cpyrt::CStringArrayConverter::SetArg(PyObject* pyobject, Parameter& para,
                                          CallContext* ctxt) {
  if (Py_TYPE(pyobject) == GetCTypesPtrType(ct_c_char_p) ||
      (1 < fShape.ndim() &&
       PyObject_IsInstance(pyobject, (PyObject*)GetCTypesType(ct_c_pointer)))) {
    // 2nd predicate is ebatable: it's a catch-all for ctypes-styled
    // multi-dimensional objects, which at this point does not check further
    // dimensionality
    para.fValue.fVoidp = (void*)((cpyrt_tagCDataObject*)pyobject)->b_ptr;
    para.fTypeCode = 'V';
    return true;
 
  } else if (PySequence_Check(pyobject) && !PyUnicode_Check(pyobject) &&
             !PyBytes_Check(pyobject)) {
    // for (auto& p : fBuffer) free(p);
    fBuffer.clear();
 
    size_t len = (size_t)PySequence_Size(pyobject);
    if (len == (size_t)-1) {
      PyErr_SetString(PyExc_ValueError,
                      "can not convert sequence object of unknown length");
      return false;
    }
 
    fBuffer.reserve(len);
    for (size_t i = 0; i < len; ++i) {
      PyObject* item = PySequence_GetItem(pyobject, i);
      if (item) {
        Py_ssize_t sz;
        const char* p = cpyrt_PyText_AsStringAndSize(item, &sz);
        Py_DECREF(item);
 
        if (p)
          fBuffer.push_back(p);
        else {
          PyErr_Format(PyExc_TypeError, "could not convert item %d to string",
                       (int)i);
          return false;
        }
 
      } else
        return false;
    }
 
    para.fValue.fVoidp = (void*)fBuffer.data();
    para.fTypeCode = 'p';
    return true;
  }
 
  return SCharArrayConverter::SetArg(pyobject, para, ctxt);
}
 
//----------------------------------------------------------------------------
PyObject* cpyrt::CStringArrayConverter::FromMemory(void* address) {
  if (fIsFixed)
    return CreateLowLevelView(*(char**)address, fShape);
  else if (fShape[0] == UNKNOWN_SIZE)
    return CreateLowLevelViewString((const char**)address, fShape);
  return CreateLowLevelViewString(*(const char***)address, fShape);
}
 
bool cpyrt::CStringArrayConverter::ToMemory(PyObject* value, void* address,
                                            PyObject* ctxt) {
  // Unlike the other array converters, this one also accepts a Python string.
  Py_ssize_t len;
  if (const char* cstr = cpyrt_PyText_AsStringAndSize(value, &len)) {
    return ToArrayFromBuffer<char>(value, address, ctxt, cstr, len, fShape,
                                   fIsFixed);
  }
  return SCharArrayConverter::ToMemory(value, address, ctxt);
}
 
//----------------------------------------------------------------------------
PyObject* cpyrt::NonConstCStringArrayConverter::FromMemory(void* address) {
  if (fIsFixed)
    return CreateLowLevelView(*(char**)address, fShape);
  else if (fShape[0] == UNKNOWN_SIZE)
    return CreateLowLevelViewString((char**)address, fShape);
  return CreateLowLevelViewString(*(char***)address, fShape);
}
 
//- converters for special cases ---------------------------------------------
bool cpyrt::NullptrConverter::SetArg(PyObject* pyobject, Parameter& para,
                                     CallContext* /* ctxt */) {
  // Only allow C++11 style nullptr to pass
  if (pyobject == gNullPtrObject || pyobject == gDefaultObject) {
    para.fValue.fVoidp = nullptr;
    para.fTypeCode = 'p';
    return true;
  }
  return false;
}
 
//----------------------------------------------------------------------------
template <typename T>
static inline bool cpyrt_PyUnicodeAsBytes2Buffer(PyObject* pyobject,
                                                 T& buffer) {
  PyObject* pybytes = nullptr;
  if (PyBytes_Check(pyobject)) {
    Py_INCREF(pyobject);
    pybytes = pyobject;
  } else if (PyUnicode_Check(pyobject)) {
    pybytes = PyUnicode_AsUTF8String(pyobject);
  }
 
  if (pybytes) {
    Py_ssize_t len;
    const char* cstr = nullptr;
    PyBytes_AsStringAndSize(pybytes, (char**)&cstr, &len);
    if (cstr)
      buffer = T{cstr, (typename T::size_type)len};
    Py_DECREF(pybytes);
    return (bool)cstr;
  }
 
  return false;
}
 
#define CPPJIT_IMPL_STRING_AS_PRIMITIVE_CONVERTER(name, type, F1, F2)          \
  cpyrt::name##Converter::name##Converter(bool keepControl)                    \
      : InstanceConverter(interop::GetFullScope(#type), keepControl) {}        \
                                                                               \
  bool cpyrt::name##Converter::SetArg(PyObject* pyobject, Parameter& para,     \
                                      CallContext* ctxt) {                     \
    if (cpyrt_PyUnicodeAsBytes2Buffer(pyobject, fBuffer)) {                    \
      para.fValue.fVoidp = &fBuffer;                                           \
      para.fTypeCode = 'V';                                                    \
      return true;                                                             \
    }                                                                          \
                                                                               \
    PyErr_Clear();                                                             \
    if (!PyLong_Check(pyobject)) {                                             \
      bool result = InstanceConverter::SetArg(pyobject, para, ctxt);           \
      para.fTypeCode = 'V';                                                    \
      return result;                                                           \
    }                                                                          \
                                                                               \
    return false;                                                              \
  }                                                                            \
                                                                               \
  PyObject* cpyrt::name##Converter::FromMemory(void* address) {                \
    if (address)                                                               \
      return InstanceConverter::FromMemory(address);                           \
    auto* empty = new type();                                                  \
    return BindCppObjectNoCast(interop::TCppObject_t((void*)empty), fClass,    \
                               CPPInstance::kIsOwner);                         \
  }                                                                            \
                                                                               \
  bool cpyrt::name##Converter::ToMemory(PyObject* value, void* address,        \
                                        PyObject* ctxt) {                      \
    if (cpyrt_PyUnicodeAsBytes2Buffer(value, *((type*)address)))               \
      return true;                                                             \
    return InstanceConverter::ToMemory(value, address, ctxt);                  \
  }
 
CPPJIT_IMPL_STRING_AS_PRIMITIVE_CONVERTER(STLString, std::string, c_str, size)
 
cpyrt::STLWStringConverter::STLWStringConverter(bool keepControl)
    : InstanceConverter(interop::GetFullScope("std::wstring"), keepControl) {}
 
bool cpyrt::STLWStringConverter::SetArg(PyObject* pyobject, Parameter& para,
                                        CallContext* ctxt) {
  if (PyUnicode_Check(pyobject)) {
    Py_ssize_t len = PyUnicode_GET_LENGTH(pyobject);
    fBuffer.resize(len);
    PyUnicode_AsWideChar(pyobject, &fBuffer[0], len);
    para.fValue.fVoidp = &fBuffer;
    para.fTypeCode = 'V';
    return true;
  }
 
  if (!PyLong_Check(pyobject)) {
    bool result = InstancePtrConverter<false>::SetArg(pyobject, para, ctxt);
    para.fTypeCode = 'V';
    return result;
  }
 
  return false;
}
 
PyObject* cpyrt::STLWStringConverter::FromMemory(void* address) {
  if (address)
    return PyUnicode_FromWideChar(((std::wstring*)address)->c_str(),
                                  ((std::wstring*)address)->size());
  wchar_t w = L'\0';
  return PyUnicode_FromWideChar(&w, 0);
}
 
bool cpyrt::STLWStringConverter::ToMemory(PyObject* value, void* address,
                                          PyObject* ctxt) {
  if (PyUnicode_Check(value)) {
    Py_ssize_t len = PyUnicode_GET_LENGTH(value);
    wchar_t* buf = new wchar_t[len + 1];
    PyUnicode_AsWideChar(value, buf, len);
    *((std::wstring*)address) = std::wstring(buf, len);
    delete[] buf;
    return true;
  }
  return InstanceConverter::ToMemory(value, address, ctxt);
}
 
cpyrt::STLStringViewConverter::STLStringViewConverter(bool keepControl)
    : InstanceConverter(interop::GetFullScope("std::string_view"),
                        keepControl) {}
 
bool cpyrt::STLStringViewConverter::SetArg(PyObject* pyobject, Parameter& para,
                                           CallContext* ctxt) {
  // normal instance convertion (eg. string_view object passed)
  if (!PyLong_Check(pyobject)) {
    CallContextRAII<CallContext::kNoImplicit> noimp(ctxt);
    if (InstanceConverter::SetArg(pyobject, para, ctxt)) {
      para.fTypeCode = 'V';
      return true;
    } else
      PyErr_Clear();
  }
 
  // passing of a Python string; buffering done Python-side b/c str is immutable
  Py_ssize_t len;
  const char* cstr = cpyrt_PyText_AsStringAndSize(pyobject, &len);
  if (cstr) {
    SetLifeLine(ctxt->fPyContext, pyobject, (intptr_t)this);
    fBuffer = std::string_view(cstr, (std::string_view::size_type)len);
    para.fValue.fVoidp = &fBuffer;
    para.fTypeCode = 'V';
    return true;
  }
 
  if (!CPPInstance_Check(pyobject))
    return false;
 
  // special case of a C++ std::string object; life-time management is left to
  // the caller to ensure any external changes propagate correctly
  if (CPPInstance_Check(pyobject)) {
    static interop::TCppScope_t sStringID =
        interop::GetUnderlyingScope(interop::GetFullScope("std::string"));
    CPPInstance* pyobj = (CPPInstance*)pyobject;
    if (pyobj->ObjectIsA() == sStringID) {
      void* ptr = pyobj->GetObject();
      if (!ptr)
        return false; // leaves prior conversion error for report
 
      PyErr_Clear();
 
      fBuffer = *((std::string*)ptr);
      para.fValue.fVoidp = &fBuffer;
      para.fTypeCode = 'V';
      return true;
    }
  }
 
  return false;
}
 
PyObject* cpyrt::STLStringViewConverter::FromMemory(void* address) {
  if (address)
    return InstanceConverter::FromMemory(address);
  auto* empty = new std::string_view();
  return BindCppObjectNoCast(empty, fClass, CPPInstance::kIsOwner);
}
 
bool cpyrt::STLStringViewConverter::ToMemory(PyObject* value, void* address,
                                             PyObject* ctxt) {
  // common case of simple object assignment
  if (InstanceConverter::ToMemory(value, address, ctxt))
    return true;
 
  // assignment of a Python string; buffering done Python-side b/c str is
  // immutable
  Py_ssize_t len;
  const char* cstr = cpyrt_PyText_AsStringAndSize(value, &len);
  if (cstr) {
    SetLifeLine(ctxt, value, (intptr_t)this);
    *reinterpret_cast<std::string_view*>(address) =
        std::string_view(cstr, (std::string_view::size_type)len);
    return true;
  }
 
  return false;
}
 
bool cpyrt::STLStringMoveConverter::SetArg(PyObject* pyobject, Parameter& para,
                                           CallContext* ctxt) {
  // convert <pyobject> to C++ std::string&&, set arg for call
  int moveit_reason = 3; // move on temporary fBuffer
  if (CPPInstance_Check(pyobject)) {
    CPPInstance* pyobj = (CPPInstance*)pyobject;
    if (pyobj->fFlags & CPPInstance::kIsRValue) {
      pyobj->fFlags &= ~CPPInstance::kIsRValue;
      moveit_reason = 2;
    } else if (PyUnstable_Object_IsUniqueReferencedTemporary(pyobject)) {
      moveit_reason = 1;
    } else
      moveit_reason = 0;
  }
 
  if (moveit_reason) {
    bool result = this->STLStringConverter::SetArg(pyobject, para, ctxt);
    if (!result && moveit_reason == 2) // restore the movability flag?
      ((CPPInstance*)pyobject)->fFlags |= CPPInstance::kIsRValue;
    return result;
  }
 
  PyErr_SetString(PyExc_ValueError, "object is not an rvalue");
  return false; // not a temporary or movable object
}
 
//----------------------------------------------------------------------------
template <bool ISCONST>
bool cpyrt::InstancePtrConverter<ISCONST>::SetArg(PyObject* pyobject,
                                                  Parameter& para,
                                                  CallContext* ctxt) {
  // convert <pyobject> to C++ instance*, set arg for call
  CPPInstance* pyobj =
      GetCppInstance(pyobject, ISCONST ? fClass : interop::TCppScope_t{});
  if (!pyobj) {
    if (GetAddressSpecialCase(pyobject, para.fValue.fVoidp)) {
      para.fTypeCode = 'p'; // allow special cases such as nullptr
      return true;
    }
 
    // not a cppjit object (TODO: handle SWIG etc.)
    return false;
  }
 
  // smart pointers should only extract the pointer if this is NOT an implicit
  // conversion to another smart pointer
  if (pyobj->IsSmart() && IsConstructor(ctxt->fFlags) &&
      interop::IsSmartPtr(ctxt->fCurScope))
    return false;
 
  interop::TCppScope_t oisa = pyobj->ObjectIsA();
  if (oisa && (oisa == fClass || interop::IsSubclass(oisa, fClass))) {
    // depending on memory policy, some objects need releasing when passed into
    // functions
    if (!KeepControl() && !UseStrictOwnership())
      pyobj->CppOwns();
 
    // calculate offset between formal and actual arguments
    para.fValue.fVoidp = pyobj->GetObject();
    if (oisa != fClass) {
      para.fValue.fIntPtr += interop::GetBaseOffset(
          oisa, fClass, para.fValue.fVoidp, 1 /* up-cast */);
    }
 
    // set pointer (may be null) and declare success
    para.fTypeCode = 'p';
    return true;
  }
 
  return false;
}
 
//----------------------------------------------------------------------------
template <bool ISCONST>
PyObject* cpyrt::InstancePtrConverter<ISCONST>::FromMemory(void* address) {
  // construct python object from C++ instance read at <address>
  if (ISCONST)
    return BindCppObject(*(void**)address, fClass); // by pointer value
 
  // a writable pointer variable's proxy tracks the pointer itself, so it can
  // only down-cast where the actual class shares the address; abstract
  // declared types stay put as Python may replace the pointee (see test21)
  void* pobj = *(void**)address;
  interop::TCppScope_t klass = fClass;
  if (pobj && !interop::IsAbstract(fClass)) {
    interop::TCppScope_t actual = interop::GetActualClass(fClass, pobj);
    if (actual && actual != fClass &&
        interop::GetBaseOffset(actual, fClass, pobj, -1 /* down-cast */) == 0)
      klass = actual;
  }
  return BindCppObject(address, klass, CPPInstance::kIsReference); // modifiable
}
 
//----------------------------------------------------------------------------
template <bool ISCONST>
bool cpyrt::InstancePtrConverter<ISCONST>::ToMemory(PyObject* value,
                                                    void* address,
                                                    PyObject* /* ctxt */) {
  // convert <value> to C++ instance, write it at <address>
  CPPInstance* pyobj =
      GetCppInstance(value, ISCONST ? fClass : interop::TCppScope_t{});
  if (!pyobj) {
    void* ptr = nullptr;
    if (GetAddressSpecialCase(value, ptr)) {
      *(void**)address = ptr; // allow special cases such as nullptr
      return true;
    }
 
    // not a cppjit object (TODO: handle SWIG etc.)
    return false;
  }
 
  if (interop::IsSubclass(pyobj->ObjectIsA(), fClass)) {
    // depending on memory policy, some objects need releasing when passed into
    // functions
    if (!KeepControl() && !UseStrictOwnership())
      ((CPPInstance*)value)->CppOwns();
 
    *(void**)address = pyobj->GetObject();
    return true;
  }
 
  return false;
}
 
// TODO: CONSOLIDATE Instance, InstanceRef, InstancePtr ...
 
//----------------------------------------------------------------------------
bool cpyrt::InstanceConverter::SetArg(PyObject* pyobject, Parameter& para,
                                      CallContext* ctxt) {
  // convert <pyobject> to C++ instance, set arg for call
  CPPInstance* pyobj = GetCppInstance(pyobject, fClass);
  if (pyobj) {
    auto oisa = pyobj->ObjectIsA();
    if (oisa && ((oisa == (interop::IsTypedefed(fClass)
                               ? interop::GetUnderlyingScope(fClass)
                               : fClass)) ||
                 interop::IsSubclass(oisa, fClass))) {
      // calculate offset between formal and actual arguments
      para.fValue.fVoidp = pyobj->GetObject();
      if (!para.fValue.fVoidp)
        return false;
 
      if (oisa != fClass) {
        para.fValue.fIntPtr += interop::GetBaseOffset(
            pyobj->ObjectIsA(), fClass, para.fValue.fVoidp, 1 /* up-cast */);
      }
 
      para.fTypeCode = 'V';
      return true;
    }
  }
 
  return (bool)ConvertImplicit(fClass, pyobject, para, ctxt);
}
 
//----------------------------------------------------------------------------
PyObject* cpyrt::InstanceConverter::FromMemory(void* address) {
  // This should not need a cast (ie. BindCppObjectNoCast), but performing the
  // cast here means callbacks receive down-casted object when passed by-ptr,
  // which is needed for object identity. The latter case is assumed to be more
  // common than conversion of (global) objects.
  return BindCppObject((interop::TCppObject_t)address, fClass);
}
 
//----------------------------------------------------------------------------
bool cpyrt::InstanceConverter::ToMemory(PyObject* value, void* address,
                                        PyObject* /* ctxt */) {
  // assign value to C++ instance living at <address> through assignment
  // operator
  PyObject* pyobj = BindCppObjectNoCast(address, fClass);
  PyObject* result =
      PyObject_CallMethodOneArg(pyobj, PyStrings::gAssign, value);
  Py_DECREF(pyobj);
 
  if (result) {
    Py_DECREF(result);
    return true;
  }
  return false;
}
 
//----------------------------------------------------------------------------
bool cpyrt::InstanceRefConverter::SetArg(PyObject* pyobject, Parameter& para,
                                         CallContext* ctxt) {
  // convert <pyobject> to C++ instance&, set arg for call
  CPPInstance* pyobj =
      GetCppInstance(pyobject, fIsConst ? fClass : interop::TCppScope_t{});
  if (pyobj) {
 
    // reject moves
    if (pyobj->fFlags & CPPInstance::kIsRValue)
      return false;
 
    // smart pointers can end up here in case of a move, so preferentially match
    // the smart type directly
    bool argset = false;
    interop::TCppScope_t cls;
    if (pyobj->IsSmart()) {
      cls = pyobj->ObjectIsA(false);
      if (cls && interop::IsSubclass(cls, fClass)) {
        para.fValue.fVoidp = pyobj->GetObjectRaw();
        argset = true;
      }
    }
 
    if (!argset) {
      cls = pyobj->ObjectIsA();
      if (cls && interop::IsSubclass(cls, fClass)) {
        para.fValue.fVoidp = pyobj->GetObject();
        argset = true;
      }
    }
 
    if (argset) {
      // do not allow null pointers through references
      if (!para.fValue.fVoidp) {
        PyErr_SetString(PyExc_ReferenceError,
                        "attempt to access a null-pointer");
        return false;
      }
 
      // calculate offset between formal and actual arguments
      if (cls != fClass) {
        para.fValue.fIntPtr += interop::GetBaseOffset(
            cls, fClass, para.fValue.fVoidp, 1 /* up-cast */);
      }
 
      para.fTypeCode = 'V';
      return true;
    }
  }
 
  if (!fIsConst) // no implicit conversion possible
    return false;
 
  return (bool)ConvertImplicit(fClass, pyobject, para, ctxt);
}
 
//----------------------------------------------------------------------------
PyObject* cpyrt::InstanceRefConverter::FromMemory(void* address) {
  return BindCppObjectNoCast((interop::TCppObject_t)address, fClass,
                             CPPInstance::kIsReference);
}
 
//----------------------------------------------------------------------------
bool cpyrt::InstanceMoveConverter::SetArg(PyObject* pyobject, Parameter& para,
                                          CallContext* ctxt) {
  // convert <pyobject> to C++ instance&&, set arg for call
  CPPInstance* pyobj =
      GetCppInstance(pyobject, fClass, true /* accept_rvalue */);
  if (!pyobj || (pyobj->fFlags & CPPInstance::kIsLValue)) {
    // implicit conversion is fine as the temporary by definition is moveable
    return (bool)ConvertImplicit(fClass, pyobject, para, ctxt);
  }
 
  // moving is same as by-ref, but have to check that move is allowed
  int moveit_reason = 0;
  if (pyobj->fFlags & CPPInstance::kIsRValue) {
    pyobj->fFlags &= ~CPPInstance::kIsRValue;
    moveit_reason = 2;
  } else if (PyUnstable_Object_IsUniqueReferencedTemporary(pyobject)) {
    moveit_reason = 1;
  }
 
  if (moveit_reason) {
    bool result = this->InstanceRefConverter::SetArg(pyobject, para, ctxt);
    if (!result && moveit_reason == 2) // restore the movability flag?
      ((CPPInstance*)pyobject)->fFlags |= CPPInstance::kIsRValue;
    return result;
  }
 
  PyErr_SetString(PyExc_ValueError, "object is not an rvalue");
  return false; // not a temporary or movable object
}
 
//----------------------------------------------------------------------------
template <bool ISREFERENCE>
bool cpyrt::InstancePtrPtrConverter<ISREFERENCE>::SetArg(
    PyObject* pyobject, Parameter& para, CallContext* /*ctxt*/) {
  // convert <pyobject> to C++ instance**, set arg for call
  CPPInstance* pyobj = GetCppInstance(pyobject);
  if (!pyobj) {
    if (!ISREFERENCE &&
        (pyobject == gNullPtrObject || pyobject == gDefaultObject)) {
      // allow nullptr as a special case
      para.fValue.fVoidp = nullptr;
      para.fTypeCode = 'p';
      return true;
    }
    return false; // not a cppjit object (TODO: handle SWIG etc.)
  }
 
  if (interop::IsSubclass(pyobj->ObjectIsA(), fClass)) {
    // depending on memory policy, some objects need releasing when passed into
    // functions
    if (!KeepControl() && !UseStrictOwnership())
      pyobj->CppOwns();
 
    // set pointer (may be null) and declare success
    if (pyobj->fFlags & CPPInstance::kIsReference) // already a ptr to object?
      para.fValue.fVoidp = pyobj->GetObjectRaw();
    else
      para.fValue.fVoidp = &pyobj->GetObjectRaw();
    para.fTypeCode = ISREFERENCE ? 'V' : 'p';
    return true;
  }
 
  return false;
}
 
//----------------------------------------------------------------------------
template <bool ISREFERENCE>
PyObject*
cpyrt::InstancePtrPtrConverter<ISREFERENCE>::FromMemory(void* address) {
  // construct python object from C++ instance* read at <address>
  return BindCppObject(*(void**)address, fClass,
                       CPPInstance::kIsReference | CPPInstance::kIsPtrPtr);
}
 
//----------------------------------------------------------------------------
template <bool ISREFERENCE>
bool cpyrt::InstancePtrPtrConverter<ISREFERENCE>::ToMemory(
    PyObject* value, void* address, PyObject* /* ctxt */) {
  // convert <value> to C++ instance*, write it at <address>
  CPPInstance* pyobj = GetCppInstance(value);
  if (!pyobj) {
    if (value == gNullPtrObject || value == gDefaultObject) {
      // allow nullptr as a special case
      *(void**)address = nullptr;
      return true;
    }
    return false; // not a cppjit object (TODO: handle SWIG etc.)
  }
 
  if (interop::IsSubclass(pyobj->ObjectIsA(), fClass)) {
    // depending on memory policy, some objects need releasing when passed into
    // functions
    if (!KeepControl() && !UseStrictOwnership())
      pyobj->CppOwns();
 
    // register the value for potential recycling
    MemoryRegulator::RegisterPyObject(pyobj, pyobj->GetObject());
 
    // set pointer (may be null) and declare success
    *(void**)address = pyobj->GetObject();
    return true;
  }
 
  return false;
}
 
namespace cppjit::cpyrt {
// Instantiate the templates
template class cpyrt::InstancePtrConverter<true>;
template class cpyrt::InstancePtrConverter<false>;
template class cpyrt::InstancePtrPtrConverter<true>;
template class cpyrt::InstancePtrPtrConverter<false>;
} // namespace cppjit::cpyrt
 
//----------------------------------------------------------------------------
bool cpyrt::InstanceArrayConverter::SetArg(PyObject* pyobject, Parameter& para,
                                           CallContext* /* txt */) {
  // convert <pyobject> to C++ instance**, set arg for call
  while (PyTuple_Check(pyobject) && !TupleOfInstances_CheckExact(pyobject)) {
    if (PyTuple_Size(pyobject) > 0)
      pyobject = PyTuple_GetItem(pyobject, 0);
    else
      return false;
  }
  if (!TupleOfInstances_CheckExact(pyobject))
    return false; // no guarantee that the tuple is okay
 
  // treat the first instance of the tuple as the start of the array, and pass
  // it by pointer (TODO: store and check sizes)
  if (PyTuple_Size(pyobject) < 1)
    return false;
 
  PyObject* first = PyTuple_GetItem(pyobject, 0);
  if (!CPPInstance_Check(first))
    return false; // should not happen
 
  if (interop::IsSubclass(((CPPInstance*)first)->ObjectIsA(), fClass)) {
    // no memory policies supported; set pointer (may be null) and declare
    // success
    para.fValue.fVoidp = ((CPPInstance*)first)->GetObject();
    para.fTypeCode = 'p';
    return true;
  }
 
  return false;
}
 
//----------------------------------------------------------------------------
PyObject* cpyrt::InstanceArrayConverter::FromMemory(void* address) {
  // construct python tuple of instances from C++ array read at <address>
  return BindCppObjectArray(*(char**)address, fClass, fShape);
}
 
//----------------------------------------------------------------------------
bool cpyrt::InstanceArrayConverter::ToMemory(PyObject* /* value */,
                                             void* /* address */,
                                             PyObject* /* ctxt */) {
  // convert <value> to C++ array of instances, write it at <address>
 
  // TODO: need to have size both for the array and from the input
  PyErr_SetString(PyExc_NotImplementedError,
                  "access to C-arrays of objects not yet implemented!");
  return false;
}
 
//___________________________________________________________________________
// Cling WORKAROUND -- classes for STL iterators are completely undefined in
// that they come in a bazillion different guises, so just do whatever
bool cpyrt::STLIteratorConverter::SetArg(PyObject* pyobject, Parameter& para,
                                         CallContext* /* ctxt */) {
  if (!CPPInstance_Check(pyobject))
    return false;
 
  // just set the pointer value, no check
  CPPInstance* pyobj = (CPPInstance*)pyobject;
  para.fValue.fVoidp = pyobj->GetObject();
  para.fTypeCode = 'V';
  return true;
}
// -- END Cling WORKAROUND
 
//----------------------------------------------------------------------------
bool cpyrt::VoidPtrRefConverter::SetArg(PyObject* pyobject, Parameter& para,
                                        CallContext* /* ctxt */) {
  // convert <pyobject> to C++ void*&, set arg for call
  CPPInstance* pyobj = GetCppInstance(pyobject);
  if (pyobj) {
    para.fValue.fVoidp = &pyobj->GetObjectRaw();
    para.fTypeCode = 'V';
    return true;
  }
 
  return false;
}
 
//----------------------------------------------------------------------------
cpyrt::VoidPtrPtrConverter::VoidPtrPtrConverter(cdims_t dims,
                                                const std::string& failureMsg)
    : fShape(dims), fFailureMsg(failureMsg) {
  fIsFixed = dims ? fShape[0] != UNKNOWN_SIZE : false;
}
 
//----------------------------------------------------------------------------
bool cpyrt::VoidPtrPtrConverter::SetArg(PyObject* pyobject, Parameter& para,
                                        CallContext* /* ctxt */) {
  // convert <pyobject> to C++ void**, set arg for call
  CPPInstance* pyobj = GetCppInstance(pyobject);
  if (pyobj) {
    // this is a C++ object, take and set its address
    para.fValue.fVoidp = &pyobj->GetObjectRaw();
    para.fTypeCode = 'p';
    return true;
  } else if (IsPyCArgObject(pyobject)) {
    cpyrt_tagPyCArgObject* carg = (cpyrt_tagPyCArgObject*)pyobject;
    if (carg->obj) {
      para.fValue.fVoidp = (void*)((cpyrt_tagCDataObject*)carg->obj)->b_ptr;
      para.fTypeCode = 'p';
      return true;
    }
  }
 
  // buffer objects are allowed under "user knows best" (this includes the
  // buffer interface to ctypes.c_void_p, which results in a void**)
  Py_ssize_t buflen =
      Utility::GetBuffer(pyobject, '*', 1, para.fValue.fVoidp, false);
 
  // ok if buffer exists (can't perform any useful size checks)
  if (para.fValue.fVoidp && buflen != 0) {
    para.fTypeCode = 'p';
    return true;
  }
 
  return false;
}
 
//----------------------------------------------------------------------------
PyObject* cpyrt::VoidPtrPtrConverter::FromMemory(void* address) {
  // read a void** from address; since this is unknown, uintptr_t is used (user
  // can cast)
  if (!address || *(ptrdiff_t*)address == 0) {
    Py_INCREF(gNullPtrObject);
    return gNullPtrObject;
  }
  if (!fIsFixed)
    return CreatePointerView((uintptr_t**)address, fShape);
  return CreatePointerView(*(uintptr_t**)address, fShape);
}
 
//----------------------------------------------------------------------------
bool cpyrt::PyObjectConverter::SetArg(PyObject* pyobject, Parameter& para,
                                      CallContext* /* ctxt */) {
  // by definition: set and declare success
  para.fValue.fVoidp = pyobject;
  para.fTypeCode = 'p';
  return true;
}
 
PyObject* cpyrt::PyObjectConverter::FromMemory(void* address) {
  // construct python object from C++ PyObject* read at <address>
  PyObject* pyobject = *((PyObject**)address);
 
  if (!pyobject) {
    Py_RETURN_NONE;
  }
 
  Py_INCREF(pyobject);
  return pyobject;
}
 
bool cpyrt::PyObjectConverter::ToMemory(PyObject* value, void* address,
                                        PyObject* /* ctxt */) {
  // no conversion needed, write <value> at <address>
  Py_INCREF(value);
  Py_XDECREF(*((PyObject**)address));
  *((PyObject**)address) = value;
  return true;
}
 
//- function pointer converter -----------------------------------------------
static unsigned int sWrapperCounter = 0;
// cache mapping signature/return type to python callable and corresponding
// wrapper
typedef std::string RetSigKey_t;
static std::unordered_map<RetSigKey_t, std::vector<void*>> sWrapperFree;
static std::unordered_map<RetSigKey_t, std::unordered_map<PyObject*, void*>>
    sWrapperLookup;
static std::unordered_map<PyObject*, std::pair<void*, RetSigKey_t>>
    sWrapperWeakRefs;
static std::unordered_map<void*, PyObject**> sWrapperReference;
 
static void GetSignatureFromFnType(interop::TCppType_t fn_type,
                                   std::string& ret, std::string& sig) {
  std::vector<interop::TCppType_t> types;
  interop::GetFnTypeSig(fn_type, types);
  assert(types.size() >= 1);
  ret = interop::GetTypeAsString(types[0]);
  sig = "(";
  bool f = false;
  for (size_t i = 1; i < types.size(); i++) {
    if (f)
      sig += ", ";
    else
      f = true;
    sig += interop::GetTypeAsString(types[i]);
  }
  sig += ")";
}
 
static PyObject* WrapperCacheEraser(PyObject*, PyObject* pyref) {
  auto ipos = sWrapperWeakRefs.find(pyref);
  if (ipos != sWrapperWeakRefs.end()) {
    auto key = ipos->second.second;
 
    // disable this callback and store on free list for possible re-use
    void* wpraddress = ipos->second.first;
    PyObject** oldref = sWrapperReference[wpraddress];
    const auto& lookup = sWrapperLookup.find(key);
    if (lookup != sWrapperLookup.end())
      lookup->second.erase(*oldref);
    *oldref = nullptr; // to detect deletions
    sWrapperFree[ipos->second.second].push_back(wpraddress);
 
    // clean up and remove weak reference from admin
    Py_DECREF(ipos->first);
    sWrapperWeakRefs.erase(ipos);
  }
 
  Py_RETURN_NONE;
}
static PyMethodDef gWrapperCacheEraserMethodDef = {
    const_cast<char*>("internal_WrapperCacheEraser"),
    (PyCFunction)WrapperCacheEraser, METH_O, nullptr};
 
static void* PyFunction_AsCPointer(PyObject* pyobject,
                                   const interop::TCppType_t fn_type,
                                   bool allowCppInstance) {
  // Convert a bound C++ function pointer or callable python object to a C-style
  // function pointer. The former is direct, the latter involves a JIT-ed
  // wrapper.
  static PyObject* sWrapperCacheEraser =
      PyCFunction_New(&gWrapperCacheEraserMethodDef, nullptr);
 
  using namespace cppjit::cpyrt;
 
  if (CPPOverload_Check(pyobject)) {
    CPPOverload* ol = (CPPOverload*)pyobject;
    if (!ol->fMethodInfo || ol->fMethodInfo->fMethods.empty())
      return nullptr;
 
    // find the overload with matching signature
    for (auto& m : ol->fMethodInfo->fMethods) {
      if (m->IsSimilarFnType(fn_type)) {
        void* fptr = (void*)m->GetFunctionAddress();
        if (fptr)
          return fptr;
      }
    }
    return nullptr;
  }
 
  if (TemplateProxy_Check(pyobject)) {
    // get the actual underlying template matching the signature
    TemplateProxy* pytmpl = (TemplateProxy*)pyobject;
    std::string fullname = pytmpl->fTI->fCppName;
    if (pytmpl->fTemplateArgs)
      fullname += PyUnicode_AsUTF8(pytmpl->fTemplateArgs);
    interop::TCppScope_t scope = ((CPPClass*)pytmpl->fTI->fPyClass)->fCppType;
    std::string ret{}, sig{};
    GetSignatureFromFnType(fn_type, ret, sig);
    interop::TCppMethod_t cppmeth = interop::GetMethodTemplate(
        scope, fullname, sig.substr(1, sig.size() - 2));
    if (cppmeth) {
      void* fptr = (void*)interop::GetFunctionAddress(cppmeth, false);
      if (fptr)
        return fptr;
    }
    return nullptr;
  }
 
  if (PyObject_IsInstance(pyobject, (PyObject*)GetCTypesType(ct_c_funcptr))) {
    // ctypes function pointer
    void* fptr = *(void**)((cpyrt_tagCDataObject*)pyobject)->b_ptr;
    return fptr;
  }
 
  if (PyCallable_Check(pyobject) &&
      (allowCppInstance || !CPPInstance_Check(pyobject))) {
    // generic python callable: create a C++ wrapper function
    // Sometimes we don't want to take this branch if the object is a C++
    // instance, because C++ doesn't allow converting functor objects to
    // function pointers, but only to std::function.
    void* wpraddress = nullptr;
 
    std::string ret{}, sig{};
    GetSignatureFromFnType(fn_type, ret, sig);
    sig = "(void)" == sig ? "()" : sig;
 
    // re-use existing wrapper if possible
    auto key = ret + sig;
    const auto& lookup = sWrapperLookup.find(key);
    if (lookup != sWrapperLookup.end()) {
      const auto& existing = lookup->second.find(pyobject);
      if (existing != lookup->second.end() &&
          *sWrapperReference[existing->second] == pyobject)
        wpraddress = existing->second;
    }
 
    // check for a pre-existing, unused, wrapper if not found
    if (!wpraddress) {
      const auto& freewrap = sWrapperFree.find(key);
      if (freewrap != sWrapperFree.end() && !freewrap->second.empty()) {
        wpraddress = freewrap->second.back();
        freewrap->second.pop_back();
        *(sWrapperReference[wpraddress]) = pyobject;
        sWrapperLookup[key][pyobject] = wpraddress;
        PyObject* wref = PyWeakref_NewRef(pyobject, sWrapperCacheEraser);
        if (wref)
          sWrapperWeakRefs[wref] = std::make_pair(wpraddress, key);
        else
          PyErr_Clear(); // happens for builtins which don't need this
      }
    }
 
    // create wrapper if no re-use possible
    if (!wpraddress) {
      if (!Utility::IncludePython())
        return nullptr;
 
      // extract argument types
      const std::vector<std::string>& argtypes =
          TypeManip::extract_arg_types(sig);
      int nArgs = (int)argtypes.size();
 
      // wrapper name
      std::ostringstream wname;
      wname << "fptr_wrap" << ++sWrapperCounter;
 
      // build wrapper function code
      std::ostringstream code;
      code << "namespace __cppjit_internal {\n  " << ret << " " << wname.str()
           << "(";
      for (int i = 0; i < nArgs; ++i) {
        code << argtypes[i] << " arg" << i;
        if (i != nArgs - 1)
          code << ", ";
      }
      code << ") {\n"
           << "    cppjit::cpyrt::PythonGILRAII python_gil_raii;\n";
 
      // start function body
      Utility::ConstructCallbackPreamble(ret, argtypes, code);
 
      // create a referenceable pointer
      PyObject** ref = new PyObject* {pyobject};
 
      // function call itself and cleanup
      code << "    PyObject** ref = (PyObject**)" << (intptr_t)ref
           << ";\n"
              "    PyObject* pyresult = nullptr;\n"
              "    if (*ref) pyresult = PyObject_CallFunctionObjArgs(*ref";
      for (int i = 0; i < nArgs; ++i)
        code << ", pyargs[" << i << "]";
      code << ", NULL);\n"
              "    else PyErr_SetString(PyExc_TypeError, \"callable was "
              "deleted\");\n";
 
      // close
      Utility::ConstructCallbackReturn(ret, nArgs, code);
 
      // end of namespace
      code << "}";
 
      // finally, compile the code
      if (!interop::Compile(code.str()))
        return nullptr;
 
      // TODO: is there no easier way?
      static interop::TCppScope_t scope =
          interop::GetScope("__cppjit_internal");
      const auto& methods = interop::GetMethodsFromName(scope, wname.str());
      wpraddress = interop::GetFunctionAddress(methods[0], false);
      sWrapperReference[wpraddress] = ref;
 
      // cache the new wrapper
      sWrapperLookup[key][pyobject] = wpraddress;
      PyObject* wref = PyWeakref_NewRef(pyobject, sWrapperCacheEraser);
      if (wref)
        sWrapperWeakRefs[wref] = std::make_pair(wpraddress, key);
      else
        PyErr_Clear(); // happens for builtins which don't need this
    }
 
    // now pass the pointer to the wrapper function (may be null)
    return wpraddress;
  }
 
  return nullptr;
}
 
bool cpyrt::FunctionPointerConverter::SetArg(PyObject* pyobject,
                                             Parameter& para,
                                             CallContext* ctxt) {
  // special case: allow nullptr singleton:
  if (pyobject == gNullPtrObject || pyobject == gDefaultObject) {
    para.fValue.fVoidp = nullptr;
    para.fTypeCode = 'p';
    return true;
  }
 
  // normal case, get a function pointer
  void* fptr = PyFunction_AsCPointer(pyobject, fFnType, fAllowCppInstance);
  if (fptr) {
    SetLifeLine(ctxt->fPyContext, pyobject, (intptr_t)this);
    para.fValue.fVoidp = fptr;
    para.fTypeCode = 'p';
    return true;
  }
 
  return false;
}
 
PyObject* cpyrt::FunctionPointerConverter::FromMemory(void* address) {
  // A function pointer in clang is represented by a Type, not a FunctionDecl
  // and it's not possible to get the latter from the former: the backend will
  // need to support both. Since that is far in the future, we'll use a
  // std::function instead.
  if (address) {
    std::string ret{}, sig{};
    GetSignatureFromFnType(fFnType, ret, sig);
    return Utility::FuncPtr2StdFunction(ret, sig, *(void**)address);
  }
  PyErr_SetString(PyExc_TypeError, "can not convert null function pointer");
  return nullptr;
}
 
bool cpyrt::FunctionPointerConverter::ToMemory(PyObject* pyobject,
                                               void* address, PyObject* ctxt) {
  // special case: allow nullptr singleton:
  if (pyobject == gNullPtrObject || pyobject == gDefaultObject) {
    *((void**)address) = nullptr;
    return true;
  }
 
  // normal case, get a function pointer
  void* fptr = PyFunction_AsCPointer(pyobject, fFnType, fAllowCppInstance);
  if (fptr) {
    SetLifeLine(ctxt, pyobject, (intptr_t)address);
    *((void**)address) = fptr;
    return true;
  }
 
  return false;
}
 
//- std::function converter --------------------------------------------------
bool cpyrt::StdFunctionConverter::SetArg(PyObject* pyobject, Parameter& para,
                                         CallContext* ctxt) {
  // prefer normal "object" conversion
  CallContextRAII<CallContext::kNoImplicit> noimp(ctxt);
  if (fConverter->SetArg(pyobject, para, ctxt))
    return true;
 
  PyErr_Clear();
 
  // else create a wrapper function
  if (this->FunctionPointerConverter::SetArg(pyobject, para, ctxt)) {
    // retrieve the wrapper pointer and capture it in a temporary std::function,
    // then try normal conversion a second time
    PyObject* func =
        this->FunctionPointerConverter::FromMemory(&para.fValue.fVoidp);
    if (func) {
      SetLifeLine(ctxt->fPyContext, func, (intptr_t)this);
      bool result = fConverter->SetArg(func, para, ctxt);
      if (result)
        ctxt->AddTemporary(func);
      else
        Py_DECREF(func);
      return result;
    }
  }
 
  return false;
}
 
PyObject* cpyrt::StdFunctionConverter::FromMemory(void* address) {
  return fConverter->FromMemory(address);
}
 
bool cpyrt::StdFunctionConverter::ToMemory(PyObject* value, void* address,
                                           PyObject* ctxt) {
  // if the value is not an std::function<> but a generic Python callable, the
  // conversion is done through the assignment, which may involve a temporary
  if (address)
    SetLifeLine(ctxt, value, (intptr_t)address);
  return fConverter->ToMemory(value, address, ctxt);
}
 
//- smart pointer converters -------------------------------------------------
bool cpyrt::SmartPtrConverter::SetArg(PyObject* pyobject, Parameter& para,
                                      CallContext* ctxt) {
  char typeCode = fIsRef ? 'p' : 'V';
 
  if (!CPPInstance_Check(pyobject)) {
    // TODO: not sure how this is correct for pass-by-ref nor does it help with
    // implicit conversions for pass-by-value
    if (fIsRef && GetAddressSpecialCase(pyobject, para.fValue.fVoidp)) {
      para.fTypeCode = typeCode; // allow special cases such as nullptr
      return true;
    }
 
    return false;
  }
 
  CPPInstance* pyobj = (CPPInstance*)pyobject;
  interop::TCppScope_t oisa = pyobj->ObjectIsA();
 
  // for the case where we have a 'hidden' smart pointer:
  if (interop::TCppScope_t tsmart = pyobj->GetSmartIsA()) {
    if (interop::IsSubclass(tsmart, fSmartPtrType)) {
      // depending on memory policy, some objects need releasing when passed
      // into functions
      if (!fKeepControl && !UseStrictOwnership())
        ((CPPInstance*)pyobject)->CppOwns();
 
      // calculate offset between formal and actual arguments
      para.fValue.fVoidp = pyobj->GetSmartObject();
      if (tsmart != fSmartPtrType) {
        para.fValue.fIntPtr += interop::GetBaseOffset(
            tsmart, fSmartPtrType, para.fValue.fVoidp, 1 /* up-cast */);
      }
 
      // set pointer (may be null) and declare success
      para.fTypeCode = typeCode;
      return true;
    }
  }
 
  // for the case where we have an 'exposed' smart pointer:
  if (!pyobj->IsSmart() && interop::IsSubclass(oisa, fSmartPtrType)) {
    // calculate offset between formal and actual arguments
    para.fValue.fVoidp = pyobj->GetObject();
    if (oisa != fSmartPtrType) {
      para.fValue.fIntPtr += interop::GetBaseOffset(
          oisa, fSmartPtrType, para.fValue.fVoidp, 1 /* up-cast */);
    }
 
    // set pointer (may be null) and declare success
    para.fTypeCode = typeCode;
    return true;
  }
 
  // for the case where we have an ordinary object to convert
  if (AllowImplicitSmartPtrConversion(ctxt) && !pyobj->IsSmart() &&
      interop::IsSubclass(oisa, fUnderlyingType)) {
    // create the relevant smart pointer and make the pyobject "smart"
    CPPInstance* pysmart = (CPPInstance*)ConvertImplicit(
        fSmartPtrType, pyobject, para, ctxt, false);
    if (!CPPInstance_Check(pysmart)) {
      Py_XDECREF(pysmart);
      return false;
    }
 
    // copy internals from the fresh smart object to the original, making it
    // smart
    pyobj->GetObjectRaw() = pysmart->GetSmartObject();
    pyobj->SetSmart(
        CreateScopeProxy(fSmartPtrType)); //(PyObject*)Py_TYPE(pysmart));
    pyobj->PythonOwns();
    pysmart->CppOwns();
    Py_DECREF(pysmart);
 
    return true;
  }
 
  // final option, try mapping pointer types held (TODO: do not allow for
  // non-const ref) Match on the declared underlying type, not the (possibly
  // downcast) dereferenced object: a unique_ptr<Base> holding a Derived is
  // still a unique_ptr<Base> and must not pass where a unique_ptr<Derived> is
  // expected.
  if (pyobj->IsSmart() &&
      interop::IsSubclass(pyobj->GetSmartUnderlyingType(), fUnderlyingType)) {
    para.fValue.fVoidp = ((CPPInstance*)pyobject)->GetSmartObject();
    para.fTypeCode = 'V';
    return true;
  }
 
  return false;
}
 
PyObject* cpyrt::SmartPtrConverter::FromMemory(void* address) {
  if (!address || !fSmartPtrType)
    return nullptr;
 
  return BindCppObjectNoCast(address, fSmartPtrType);
}
 
bool cpyrt::SmartPtrConverter::ToMemory(PyObject* value, void* address,
                                        PyObject*) {
  // assign value to C++ instance living at <address> through assignment
  // operator (this is similar to InstanceConverter::ToMemory, but prevents
  // wrapping the smart ptr)
  PyObject* pyobj =
      BindCppObjectNoCast(address, fSmartPtrType, CPPInstance::kNoWrapConv);
  PyObject* result =
      PyObject_CallMethodOneArg(pyobj, PyStrings::gAssign, value);
  Py_DECREF(pyobj);
 
  if (result) {
    Py_DECREF(result);
    return true;
  }
  return false;
}
 
//----------------------------------------------------------------------------
namespace {
 
// clang libcpp and gcc use the same structure (ptr, size)
#if defined(_LIBCPP_INITIALIZER_LIST) || defined(__GNUC__)
struct faux_initlist {
  typedef size_t size_type;
  typedef void* iterator;
  iterator _M_array;
  size_type _M_len;
};
#elif defined(_MSC_VER)
struct faux_initlist {
  typedef char* iterator;
  iterator _M_array; // ie. _First;
  iterator _Last;
};
#else
#define NO_KNOWN_INITIALIZER_LIST 1
#endif
 
} // unnamed namespace
 
cpyrt::InitializerListConverter::InitializerListConverter(
    interop::TCppScope_t klass, std::string const& value_type)
 
    : InstanceConverter{klass}, fValueTypeName{value_type},
      fValueType{interop::GetScope(value_type)},
      fValueSize{interop::SizeOfType(interop::GetType(value_type, true))} {}
 
cpyrt::InitializerListConverter::~InitializerListConverter() {
  for (Converter* converter : fConverters) {
    if (converter && converter->HasState())
      delete converter;
  }
  if (fBuffer)
    Clear();
}
 
void cpyrt::InitializerListConverter::Clear() {
  if (fValueType) {
    faux_initlist* fake = (faux_initlist*)fBuffer;
#if defined(_LIBCPP_INITIALIZER_LIST) || defined(__GNUC__)
    for (faux_initlist::size_type i = 0; i < fake->_M_len; ++i) {
#elif defined(_MSC_VER)
    for (size_t i = 0; (fake->_M_array + i * fValueSize) != fake->_Last; ++i) {
#endif
      void* memloc = (char*)fake->_M_array + i * fValueSize;
      interop::CallDestructor(fValueType, (interop::TCppObject_t)memloc);
    }
  }
 
  free(fBuffer);
  fBuffer = nullptr;
}
 
bool cpyrt::InitializerListConverter::SetArg(PyObject* pyobject,
                                             Parameter& para,
                                             CallContext* ctxt) {
#ifdef NO_KNOWN_INITIALIZER_LIST
  return false;
#else
  if (fBuffer)
    Clear();
 
  // convert the given argument to an initializer list temporary; this is purely
  // meant to be a syntactic thing, so only _python_ sequences are allowed;
  // bound C++ proxies (likely explicitly created std::initializer_list, go
  // through an instance converter
  if (!PySequence_Check(pyobject) || PyUnicode_Check(pyobject) ||
      PyBytes_Check(pyobject))
    return false;
 
  if (CPPInstance_Check(pyobject))
    return this->InstanceConverter::SetArg(pyobject, para, ctxt);
 
  void* buf = nullptr;
  Py_ssize_t buflen =
      Utility::GetBuffer(pyobject, '*', (int)fValueSize, buf, true);
  faux_initlist* fake = nullptr;
  size_t entries = 0;
  if (buf && buflen) {
    // dealing with an array here, pass on whole-sale
    fake = (faux_initlist*)malloc(sizeof(faux_initlist));
    fBuffer = (void*)fake;
    fake->_M_array = (faux_initlist::iterator)buf;
#if defined(_LIBCPP_INITIALIZER_LIST) || defined(__GNUC__)
    fake->_M_len = (faux_initlist::size_type)buflen;
#elif defined(_MSC_VER)
    fake->_Last = fake->_M_array + buflen * fValueSize;
#endif
  } else if (fValueSize) {
    // Remove any errors set by GetBuffer(); note that if the argument was an
    // array that failed to extract because of a type mismatch, the following
    // will perform a (rather inefficient) copy. No warning is issued b/c e.g.
    // numpy doesn't do so either.
    PyErr_Clear();
 
    // Can only construct empty lists, so use a fake initializer list. For that
    // we need to construct default objects. Fail early if that cannot work.
    if (fValueType && !interop::IsDefaultConstructable(fValueType)) {
      PyErr_SetString(
          PyExc_TypeError,
          "default constructor needed for initializer list of objects");
      return false;
    }
 
    size_t len = (size_t)PySequence_Size(pyobject);
    fake = (faux_initlist*)malloc(sizeof(faux_initlist) + fValueSize * len);
    fBuffer = (void*)fake;
    fake->_M_array =
        (faux_initlist::iterator)((char*)fake + sizeof(faux_initlist));
#if defined(_LIBCPP_INITIALIZER_LIST) || defined(__GNUC__)
    fake->_M_len = (faux_initlist::size_type)len;
    for (faux_initlist::size_type i = 0; i < fake->_M_len; ++i) {
#elif defined(_MSC_VER)
    fake->_Last = fake->_M_array + len * fValueSize;
    for (size_t i = 0; (fake->_M_array + i * fValueSize) != fake->_Last; ++i) {
#endif
      PyObject* item = PySequence_GetItem(pyobject, i);
      bool convert_ok = false;
      if (item) {
        if (i >= fConverters.size())
          fConverters.emplace_back(CreateConverter(fValueTypeName));
        Converter* converter = fConverters[i];
        if (!converter) {
          if (CPPInstance_Check(item)) {
            // by convention, use byte copy
            memcpy((char*)fake->_M_array + i * fValueSize,
                   ((CPPInstance*)item)->GetObject(), fValueSize);
            convert_ok = true;
          }
        } else {
          void* memloc = (char*)fake->_M_array + i * fValueSize;
          if (fValueType) {
            // we need to construct a default object for the constructor to
            // assign into; this is clunky, but the use of a copy constructor
            // isn't much better as the Python object need not be a C++ object
            memloc = (void*)interop::Construct(fValueType, memloc).data;
            // We checked above that we are able to construct default objects of
            // fValueType.
            assert(memloc && ("failed to default construct object for type " +
                              fValueTypeName)
                                 .c_str());
            entries += 1;
          }
          if (memloc)
            convert_ok = converter->ToMemory(item, memloc);
        }
 
        Py_DECREF(item);
      } else
        PyErr_Format(PyExc_TypeError, "failed to get item %d from sequence",
                     (int)i);
 
      if (!convert_ok) {
#if defined(_LIBCPP_INITIALIZER_LIST) || defined(__GNUC__)
        fake->_M_len = (faux_initlist::size_type)entries;
#elif defined(_MSC_VER)
        fake->_Last = fake->_M_array + entries * fValueSize;
#endif
        Clear();
        return false;
      }
    }
  }
 
  if (!fake) // no buffer and value size indeterminate
    return false;
 
  para.fValue.fVoidp = (void*)fake;
  para.fTypeCode = 'V'; // means ptr that backend has to free after call
  return true;
#endif
}
 
namespace cppjit::cpyrt {
 
// raising converter to take out overloads
class NotImplementedConverter : public Converter {
public:
  NotImplementedConverter(PyObject* errorType, std::string const& message)
      : fErrorType{errorType}, fMessage{message} {}
  bool SetArg(PyObject*, Parameter&, CallContext* = nullptr) override;
 
private:
  PyObject* fErrorType;
  std::string fMessage;
};
 
} // namespace cppjit::cpyrt
 
//----------------------------------------------------------------------------
bool cpyrt::NotImplementedConverter::SetArg(PyObject*, Parameter&,
                                            CallContext*) {
  // raise a NotImplemented exception to take a method out of overload
  // resolution
  PyErr_SetString(fErrorType, fMessage.c_str());
  return false;
}
 
//- helper to refactor some code from CreateConverter ------------------------
static inline cppjit::cpyrt::Converter*
selectInstanceCnv(interop::TCppScope_t klass, const std::string& cpd,
                  cpyrt::cdims_t dims, bool isConst, bool control) {
  using namespace cppjit::cpyrt;
  Converter* result = nullptr;
 
  if (cpd == "**" || cpd == "*[]" || cpd == "&*")
    result = new InstancePtrPtrConverter<false>(klass, control);
  else if (cpd == "*&")
    result = new InstancePtrPtrConverter<true>(klass, control);
  else if (cpd == "*" && dims.ndim() == UNKNOWN_SIZE) {
    if (isConst)
      result = new InstancePtrConverter<true>(klass, control);
    else
      result = new InstancePtrConverter<false>(klass, control);
  } else if (cpd == "&")
    result = new InstanceRefConverter(klass, isConst);
  else if (cpd == "&&")
    result = new InstanceMoveConverter(klass);
  else if (cpd == "[]" || dims)
    result = new InstanceArrayConverter(klass, dims, false);
  else if (cpd == "") // by value
    result = new InstanceConverter(klass, true);
 
  return result;
}
 
//- factories ----------------------------------------------------------------
CPYRT_EXPORT
cppjit::cpyrt::Converter*
cppjit::cpyrt::CreateConverter(const std::string& fullType, cdims_t dims) {
  // The matching of the fulltype to a converter factory goes through up to five
  // levels:
  //   1) full, exact match
  //   2) match of decorated, unqualified type
  //   3) accept const ref as by value
  //   4) accept ref as pointer
  //   5) generalized cases (covers basically all C++ classes)
  //
  // If all fails, void is used, which will generate a run-time warning when
  // used.
 
  // an exactly matching converter is best
  ConvFactories_t::iterator h = gConvFactories.find(fullType);
  if (h != gConvFactories.end()) {
    return (h->second)(dims);
  }
 
  // resolve typedefs etc.
  const std::string& resolvedType = interop::ResolveName(fullType);
 
  // a full, qualified matching converter is preferred
  if (resolvedType != fullType) {
    h = gConvFactories.find(resolvedType);
    if (h != gConvFactories.end())
      return (h->second)(dims);
  }
 
  //-- nothing? ok, collect information about the type and possible
  // qualifiers/decorators
  bool isConst = strncmp(resolvedType.c_str(), "const", 5) == 0;
  const std::string& cpd = TypeManip::compound(resolvedType);
  std::string realType = TypeManip::clean_type(resolvedType, false, true);
 
  // accept unqualified type (as python does not know about qualifiers)
  h = gConvFactories.find((isConst ? "const " : "") + realType + cpd);
  if (h != gConvFactories.end())
    return (h->second)(dims);
 
  // mutable pointer references (T*&) are incompatible with Python's object
  // model; a string that resolves to no type keeps the ban
  if (!isConst && cpd == "*&") {
    interop::TCppType_t refType =
        interop::GetType(resolvedType, /* enable_slow_lookup */ true);
    if (!refType || interop::IsMutablePtrRefType(refType)) {
      return new NotImplementedConverter{
          PyExc_TypeError,
          "argument type '" + resolvedType +
              "' is not supported: non-const references to pointers (T*&) "
              "allow a function to replace the pointer itself. Python cannot "
              "represent this safely. Consider changing the"
              " C++ API to return the new pointer or use a wrapper"};
    }
  }
 
  // drop const, as that is mostly meaningless to python (with the exception
  // of c-strings, but those are specialized in the converter map)
  if (isConst) {
    h = gConvFactories.find(realType + cpd);
    if (h != gConvFactories.end())
      return (h->second)(dims);
  }
 
  //-- still nothing? try pointer instead of array (for builtins)
  if (cpd.compare(0, 3, "*[]") == 0) {
    // special case, array of pointers
    h = gConvFactories.find(realType + " ptr");
    if (h != gConvFactories.end()) {
      // upstream treats the pointer type as the array element type, but that
      // pointer is treated as a low-level view as well, unless it's a
      // void*/char* so adjust the dims
      if (realType != "void" && realType != "char") {
        dim_t newdim = dims.ndim() == UNKNOWN_SIZE ? 2 : dims.ndim() + 1;
        dims_t newdims = dims_t(newdim);
        // TODO: sometimes the array size is known and can thus be verified;
        // however, currently the meta layer does not provide this information
        newdims[0] = dims ? dims[0] : UNKNOWN_SIZE; // the array
        newdims[1] = UNKNOWN_SIZE;                  // the pointer
        if (2 < newdim) {
          for (int i = 2; i < (newdim - 1); ++i)
            newdims[i] = dims[i - 1];
        }
 
        return (h->second)(newdims);
      }
      return (h->second)(dims);
    }
 
  } else if (!cpd.empty() && (std::string::size_type)std::count(
                                 cpd.begin(), cpd.end(), '*') == cpd.size()) {
    // simple array; set or resize as necessary
    h = gConvFactories.find(realType + " ptr");
    if (h != gConvFactories.end())
      return (h->second)((!dims && 1 < cpd.size()) ? dims_t(cpd.size()) : dims);
 
  } else if (2 <= cpd.size() &&
             (std::string::size_type)std::count(cpd.begin(), cpd.end(), '[') ==
                 cpd.size() / 2) {
    // fixed array, dims will have size if available
    h = gConvFactories.find(realType + " ptr");
    if (h != gConvFactories.end())
      return (h->second)(dims);
  }
 
  //-- special case: initializer list
  if (realType.compare(0, 21, "std::initializer_list") == 0) {
    // get the type of the list and create a converter (TODO: get hold of
    // value_type?)
    auto pos = realType.find('<');
    std::string value_type =
        realType.substr(pos + 1, realType.size() - pos - 2);
    return new InitializerListConverter(interop::GetScope(realType),
                                        value_type);
  }
 
  //-- still nothing? use a generalized converter
  bool control = cpd == "&" || isConst;
 
  //-- special case: std::function
  auto pos = resolvedType.find("std::function<");
  if (pos == 0 /* std:: */ || pos == 6 /* const std:: */) {
 
    // get actual converter for normal passing
    Converter* cnv = selectInstanceCnv(interop::GetScope(realType), cpd, dims,
                                       isConst, control);
 
    if (cnv) {
      // get the type of the underlying (TODO: use target_type?)
      auto pos1 = resolvedType.find("(", pos + 14);
      auto pos2 = resolvedType.rfind(")");
      if (pos1 != std::string::npos && pos2 != std::string::npos) {
        auto sz1 = pos1 - pos - 14;
        if (resolvedType[pos + 14 + sz1 - 1] == ' ')
          sz1 -= 1;
 
        return new StdFunctionConverter(
            cnv, interop::GetType(fullType), resolvedType.substr(pos + 14, sz1),
            resolvedType.substr(pos1, pos2 - pos1 + 1));
      } else if (cnv->HasState())
        delete cnv;
    }
  }
 
#if __cplusplus >= 202002L
  //-- special case: std::span
  pos = resolvedType.find("span<");
  if (pos == 0 /* no std:: */ || pos == 5 /* with std:: */ ||
      pos == 6 /* const no std:: */ || pos == 11 /* const with std:: */) {
 
    // std::span<T>::value_type == std::remove_cv_t<T>: look it up
    interop::TCppScope_t span_scope = interop::GetScope(realType);
    interop::TCppType_t vtype = interop::ResolveType(
        interop::GetTypeFromScope(interop::GetNamed("value_type", span_scope)));
    if (span_scope && vtype) {
      std::string value_type = interop::GetTypeAsString(vtype);
      return new StdSpanConverter{value_type, span_scope};
    }
  }
#endif
 
  // converters for known C++ classes and default (void*)
  Converter* result = nullptr;
  if (interop::TCppScope_t klass = interop::GetFullScope(realType)) {
    interop::TCppScope_t raw;
    if (interop::GetSmartPtrInfo(realType, &raw, nullptr)) {
      if (cpd == "") {
        result = new SmartPtrConverter(klass, raw, control);
      } else if (cpd == "&") {
        result = new SmartPtrConverter(klass, raw);
      } else if (cpd == "*" && dims.ndim() == UNKNOWN_SIZE) {
        result = new SmartPtrConverter(klass, raw, control, true);
      }
    }
 
    if (!result) {
      // Cling WORKAROUND -- special case for STL iterators
      if (Utility::IsSTLIterator(realType)) {
        static STLIteratorConverter c;
        result = &c;
      } else
        // -- Cling WORKAROUND
        result = selectInstanceCnv(klass, cpd, dims, isConst, control);
    }
  } else {
    interop::TCppType_t typ = interop::GetType(fullType);
    if (interop::IsFunctionType(typ)) {
      // this is a function pointer or reference
      result = new FunctionPointerConverter(typ);
    }
  }
  const std::string failure_msg("Failed to convert type: " + fullType +
                                "; resolved: " + resolvedType +
                                "; real: " + realType + "; cpd: " + cpd);
 
  if (!result && cpd == "&&") {
    // for builtin, can use const-ref for r-ref
    h = gConvFactories.find("const " + realType + "&");
    if (h != gConvFactories.end())
      return (h->second)(dims);
    // else, unhandled moves
    result = new NotImplementedConverter{PyExc_NotImplementedError,
                                         "this method cannot (yet) be called"};
  }
 
  if (!result && h != gConvFactories.end())
    // converter factory available, use it to create converter
    result = (h->second)(dims);
  else if (!result) {
    // default to something reasonable, assuming "user knows best"
    if (cpd.size() == 2 && cpd != "&&") // "**", "*[]", "*&"
      result = new VoidPtrPtrConverter(dims.ndim(), failure_msg);
    else if (!cpd.empty())
      result = new VoidArrayConverter(/* keepControl= */ true,
                                      failure_msg); // "user knows best"
    else
      // fails on use
      result = new NotImplementedConverter{
          PyExc_NotImplementedError, "this method cannot (yet) be called"};
  }
 
  return result;
}
 
CPYRT_EXPORT
cppjit::cpyrt::Converter*
cppjit::cpyrt::CreateConverter(interop::TCppType_t type, cdims_t dims) {
  // The matching of the fulltype to a converter factory goes through up to five
  // levels:
  //   1) full, exact match
  //   2) match of decorated, unqualified type
  //   3) accept const ref as by value
  //   4) accept ref as pointer
  //   5) generalized cases (covers basically all C++ classes)
  //
  // If all fails, void is used, which will generate a run-time warning when
  // used.
 
  // an exactly matching converter is best
  std::string fullType = interop::GetTypeAsString(type);
  ConvFactories_t::iterator h = gConvFactories.find(fullType);
  if (h != gConvFactories.end()) {
    return (h->second)(dims);
  }
 
  // resolve typedefs etc.
  interop::TCppType_t resolvedType = interop::ResolveType(type);
  const std::string& resolvedTypeStr = interop::GetTypeAsString(resolvedType);
 
  // a by-value enum parameter exact-matches instances of the same enum; the
  // resolved type is its underlying integer, which carries the conversion
  if (interop::IsEnumType(type) && fullType != "std::byte") {
    h = gConvFactories.find(resolvedTypeStr);
    // the underlying integer may be spelled through a typedef (e.g.
    // `enum E : std::int32_t`), so fall back to its canonical spelling
    if (h == gConvFactories.end())
      h = gConvFactories.find(
          interop::GetTypeAsString(interop::ResolveType(resolvedType)));
    if (h != gConvFactories.end())
      return new EnumConverter(
          (h->second)(dims),
          interop::GetScopedFinalName(interop::GetScopeFromType(type)));
  }
 
  // a full, qualified matching converter is preferred
  if (resolvedTypeStr != fullType) {
    h = gConvFactories.find(resolvedTypeStr);
    if (h != gConvFactories.end()) {
      return (h->second)(dims);
    }
  }
 
  //-- nothing? ok, collect information about the type and possible
  // qualifiers/decorators
  bool isConst = strncmp(resolvedTypeStr.c_str(), "const", 5) == 0;
  const std::string& cpd = TypeManip::compound(resolvedTypeStr);
  interop::TCppType_t realType =
      interop::ResolveType(interop::GetRealType(type));
  std::string realTypeStr = interop::GetTypeAsString(realType);
  std::string realUnresolvedTypeStr =
      TypeManip::clean_type(fullType, false, true);
 
  // accept unqualified type (as python does not know about qualifiers)
  h = gConvFactories.find((isConst ? "const " : "") + realTypeStr + cpd);
  if (h != gConvFactories.end())
    return (h->second)(dims);
 
  // mutable pointer references (T*&) are incompatible with Python's object
  // model
  if (!isConst && cpd == "*&" && interop::IsMutablePtrRefType(resolvedType)) {
    return new NotImplementedConverter{
        PyExc_TypeError,
        "argument type '" + resolvedTypeStr +
            "' is not supported: non-const references to pointers (T*&) allow a"
            " function to replace the pointer itself. Python cannot represent "
            "this safely. Consider changing the"
            " C++ API to return the new pointer or use a wrapper"};
  }
 
  // drop const, as that is mostly meaningless to python (with the exception
  // of c-strings, but those are specialized in the converter map)
  if (isConst) {
    h = gConvFactories.find(realTypeStr + cpd);
    if (h != gConvFactories.end()) {
      return (h->second)(dims);
    }
  }
 
  //-- still nothing? try pointer instead of array (for builtins)
  if (cpd.compare(0, 3, "*[]") == 0) {
    // special case, array of pointers
    h = gConvFactories.find(realTypeStr + " ptr");
    if (h != gConvFactories.end()) {
      // upstream treats the pointer type as the array element type, but that
      // pointer is treated as a low-level view as well, unless it's a
      // void*/char* so adjust the dims
      if (realTypeStr != "void" && realTypeStr != "char") {
        dim_t newdim = dims.ndim() == UNKNOWN_SIZE ? 2 : dims.ndim() + 1;
        dims_t newdims = dims_t(newdim);
        // TODO: sometimes the array size is known and can thus be verified;
        // however, currently the meta layer does not provide this information
        newdims[0] = dims ? dims[0] : UNKNOWN_SIZE; // the array
        newdims[1] = UNKNOWN_SIZE;                  // the pointer
        if (2 < newdim) {
          for (int i = 2; i < (newdim - 1); ++i)
            newdims[i] = dims[i - 1];
        }
 
        return (h->second)(newdims);
      }
      return (h->second)(dims);
    }
 
  } else if (!cpd.empty() && (std::string::size_type)std::count(
                                 cpd.begin(), cpd.end(), '*') == cpd.size()) {
    // simple array; set or resize as necessary
    h = gConvFactories.find(realTypeStr + " ptr");
    if (h != gConvFactories.end())
      return (h->second)((!dims && 1 < cpd.size()) ? dims_t(cpd.size()) : dims);
 
  } else if (2 <= cpd.size() &&
             (std::string::size_type)std::count(cpd.begin(), cpd.end(), '[') ==
                 cpd.size() / 2) {
    // fixed array, dims will have size if available
    h = gConvFactories.find(realTypeStr + " ptr");
    if (h != gConvFactories.end())
      return (h->second)(dims);
  }
 
  //-- special case: initializer list
  if (realTypeStr.compare(0, 21, "std::initializer_list") == 0) {
    // get the type of the list and create a converter (TODO: get hold of
    // value_type?)
    auto pos = realTypeStr.find('<');
    std::string value_type =
        realTypeStr.substr(pos + 1, realTypeStr.size() - pos - 2);
    Converter* cnv = nullptr;
    bool use_byte_cnv = false;
    if (cpd == "" && interop::GetScope(value_type)) {
      // initializer list of object values does not work as the target is raw
      // memory; simply use byte copies
 
      // by convention, leave cnv as nullptr
      use_byte_cnv = true;
    } else
      cnv = CreateConverter(value_type);
    if (cnv || use_byte_cnv)
      return new InitializerListConverter(interop::GetScopeFromType(realType),
                                          value_type);
  }
 
  //-- still nothing? use a generalized converter
  bool control = cpd == "&" || isConst;
 
  //-- special case: std::function
  auto pos = resolvedTypeStr.find("std::function<");
  if (pos == 0 /* std:: */ || pos == 6 /* const std:: */) {
 
    // get actual converter for normal passing
    Converter* cnv = selectInstanceCnv(interop::GetScopeFromType(realType), cpd,
                                       dims, isConst, control);
 
    if (cnv) {
      // get the type of the underlying (TODO: use target_type?)
      auto pos1 = resolvedTypeStr.find("(", pos + 14);
      auto pos2 = resolvedTypeStr.rfind(")");
      if (pos1 != std::string::npos && pos2 != std::string::npos) {
        auto sz1 = pos1 - pos - 14;
        if (resolvedTypeStr[pos + 14 + sz1 - 1] == ' ')
          sz1 -= 1;
 
        const std::string& argsStr =
            resolvedTypeStr.substr(pos1, pos2 - pos1 + 1).c_str();
        return new StdFunctionConverter(cnv, resolvedType,
                                        resolvedTypeStr.substr(pos + 14, sz1),
                                        argsStr == "(void)" ? "()" : argsStr);
      } else if (cnv->HasState())
        delete cnv;
    }
  }
 
#if __cplusplus >= 202002L
  //-- special case: std::span
  pos = resolvedTypeStr.find("span<");
  if (pos == 0 /* no std:: */ || pos == 5 /* with std:: */ ||
      pos == 6 /* const no std:: */ || pos == 11 /* const with std:: */) {
 
    // std::span<T>::value_type == std::remove_cv_t<T>: look it up
    interop::TCppScope_t span_scope = interop::GetScopeFromType(realType);
    interop::TCppType_t vtype = interop::ResolveType(
        interop::GetTypeFromScope(interop::GetNamed("value_type", span_scope)));
    if (span_scope && vtype) {
      std::string value_type = interop::GetTypeAsString(vtype);
      return new StdSpanConverter{value_type, span_scope};
    }
  }
#endif
 
  // converters for known C++ classes and default (void*)
  Converter* result = nullptr;
  interop::TCppScope_t klass = interop::GetScopeFromType(realType);
  if (interop::IsFunctionType(resolvedType)) {
    // this is a function function pointer or reference
    result = new FunctionPointerConverter(resolvedType);
  } else if ((realTypeStr != "std::byte") &&
             (klass || (klass = interop::GetFullScope(realTypeStr)))) {
    // std::byte is a special enum class used to access raw memory
    interop::TCppScope_t raw;
    if (interop::GetSmartPtrInfo(realTypeStr, &raw, nullptr)) {
      if (cpd == "") {
        result = new SmartPtrConverter(klass, raw, control);
      } else if (cpd == "&") {
        result = new SmartPtrConverter(klass, raw);
      } else if (cpd == "*" && dims.ndim() == UNKNOWN_SIZE) {
        result = new SmartPtrConverter(klass, raw, control, true);
      }
    }
 
    if (!result) {
      // Cling WORKAROUND -- special case for STL iterators
      if (realTypeStr.rfind("__gnu_cxx::__normal_iterator", 0) /* vector */ == 0
#ifdef __APPLE__
          || realTypeStr.rfind("__wrap_iter", 0) == 0
#endif
          // TODO: Windows?
      ) {
        static STLIteratorConverter c;
        result = &c;
      } else if (realTypeStr != "int8_t" and realTypeStr != "uint8_t") {
        // -- Cling WORKAROUND
        result = selectInstanceCnv(klass, cpd, dims, isConst, control);
      }
    }
  }
  const std::string failure_msg(
      "Failed to convert type: " + fullType + "; resolved: " + resolvedTypeStr +
      "; real: " + realTypeStr +
      "; realUnresolvedType: " + realUnresolvedTypeStr + "; cpd: " + cpd);
 
  if (!result && cpd == "&&") {
    // for builtin, can use const-ref for r-ref
    h = gConvFactories.find("const " + realTypeStr + "&");
    if (h != gConvFactories.end())
      return (h->second)(dims);
    h = gConvFactories.find("const " + realUnresolvedTypeStr + "&");
    if (h != gConvFactories.end())
      return (h->second)(dims);
    // else, unhandled moves
    result = new NotImplementedConverter{PyExc_NotImplementedError,
                                         "this method cannot (yet) be called"};
  }
 
  if (!result && h != gConvFactories.end()) {
    // converter factory available, use it to create converter
    result = (h->second)(dims);
  } else if (!result) {
    // default to something reasonable, assuming "user knows best"
    if (cpd.size() == 2 && cpd != "&&") { // "**", "*[]", "*&"
      result = new VoidPtrPtrConverter(dims.ndim(), failure_msg);
    } else if (!cpd.empty()) {
      result = new VoidArrayConverter(/* keepControl= */ true,
                                      failure_msg); // "user knows best"
    } else {
      // fails on use
      result = new NotImplementedConverter{
          PyExc_NotImplementedError, "this method cannot (yet) be called"};
    }
  }
 
  return result;
}
 
//----------------------------------------------------------------------------
CPYRT_EXPORT
void cppjit::cpyrt::DestroyConverter(Converter* p) {
  if (p && p->HasState())
    delete p; // state-less converters are always shared
}
 
//----------------------------------------------------------------------------
CPYRT_EXPORT
bool cpyrt::RegisterConverter(const std::string& name, cf_t fac) {
  // register a custom converter
  auto f = gConvFactories.find(name);
  if (f != gConvFactories.end())
    return false;
 
  gConvFactories[name] = fac;
  return true;
}
 
//----------------------------------------------------------------------------
CPYRT_EXPORT
bool cpyrt::RegisterConverterAlias(const std::string& name,
                                   const std::string& target) {
  // register a custom converter that is a reference to an existing converter
  auto f = gConvFactories.find(name);
  if (f != gConvFactories.end())
    return false;
 
  auto t = gConvFactories.find(target);
  if (t == gConvFactories.end())
    return false;
 
  gConvFactories[name] = t->second;
  return true;
}
 
//----------------------------------------------------------------------------
CPYRT_EXPORT
bool cpyrt::UnregisterConverter(const std::string& name) {
  // remove a custom converter
  auto f = gConvFactories.find(name);
  if (f != gConvFactories.end()) {
    gConvFactories.erase(f);
    return true;
  }
  return false;
}
 
//----------------------------------------------------------------------------
namespace {
 
using namespace cppjit::cpyrt;
 
inline static std::string::size_type dims2stringsz(cdims_t d) {
  return (d && d.ndim() != UNKNOWN_SIZE) ? d[0] : std::string::npos;
}
 
#define STRINGVIEW "std::basic_string_view<char>"
#define WSTRING1 "std::basic_string<wchar_t>"
#define WSTRING2                                                               \
  "std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_"  \
  "t>>"
 
//-- aliasing special case: C complex (is binary compatible with C++
// std::complex)
#ifndef _WIN32
#define CCOMPLEX_D "_Complex double"
#define CCOMPLEX_F "_Complex float"
#else
#define CCOMPLEX_D "_C_double_complex"
#define CCOMPLEX_F "_C_float_complex"
#endif
 
static struct InitConvFactories_t {
public:
  InitConvFactories_t() {
    // load all converter factories in the global map 'gConvFactories'
    cpyrt::ConvFactories_t& gf = gConvFactories;
 
    // factories for built-ins
    gf["bool"] = (cf_t) + [](cdims_t) {
      static BoolConverter c{};
      return &c;
    };
    gf["const bool&"] = (cf_t) + [](cdims_t) {
      static ConstBoolRefConverter c{};
      return &c;
    };
    gf["bool&"] = (cf_t) + [](cdims_t) {
      static BoolRefConverter c{};
      return &c;
    };
    gf["char"] = (cf_t) + [](cdims_t) {
      static CharConverter c{};
      return &c;
    };
    gf["const char&"] = (cf_t) + [](cdims_t) {
      static ConstCharRefConverter c{};
      return &c;
    };
    gf["char&"] = (cf_t) + [](cdims_t) {
      static CharRefConverter c{};
      return &c;
    };
    gf["signed char&"] = (cf_t) + [](cdims_t) {
      static SCharRefConverter c{};
      return &c;
    };
    gf["unsigned char"] = (cf_t) + [](cdims_t) {
      static UCharConverter c{};
      return &c;
    };
    gf["const unsigned char&"] = (cf_t) + [](cdims_t) {
      static ConstUCharRefConverter c{};
      return &c;
    };
    gf["unsigned char&"] = (cf_t) + [](cdims_t) {
      static UCharRefConverter c{};
      return &c;
    };
    gf["SCharAsInt"] = (cf_t) + [](cdims_t) {
      static SCharAsIntConverter c{};
      return &c;
    };
    gf["UCharAsInt"] = (cf_t) + [](cdims_t) {
      static UCharAsIntConverter c{};
      return &c;
    };
    gf["wchar_t"] = (cf_t) + [](cdims_t) {
      static WCharConverter c{};
      return &c;
    };
    gf["char16_t"] = (cf_t) + [](cdims_t) {
      static Char16Converter c{};
      return &c;
    };
    gf["char32_t"] = (cf_t) + [](cdims_t) {
      static Char32Converter c{};
      return &c;
    };
    gf["wchar_t&"] = (cf_t) + [](cdims_t) {
      static WCharRefConverter c{};
      return &c;
    };
    gf["char16_t&"] = (cf_t) + [](cdims_t) {
      static Char16RefConverter c{};
      return &c;
    };
    gf["char32_t&"] = (cf_t) + [](cdims_t) {
      static Char32RefConverter c{};
      return &c;
    };
    gf["int8_t"] = (cf_t) + [](cdims_t) {
      static Int8Converter c{};
      return &c;
    };
    gf["const int8_t&"] = (cf_t) + [](cdims_t) {
      static ConstInt8RefConverter c{};
      return &c;
    };
    gf["int8_t&"] = (cf_t) + [](cdims_t) {
      static Int8RefConverter c{};
      return &c;
    };
    gf["uint8_t"] = (cf_t) + [](cdims_t) {
      static UInt8Converter c{};
      return &c;
    };
    gf["const uint8_t&"] = (cf_t) + [](cdims_t) {
      static ConstUInt8RefConverter c{};
      return &c;
    };
    gf["uint8_t&"] = (cf_t) + [](cdims_t) {
      static UInt8RefConverter c{};
      return &c;
    };
    gf["int16_t"] = (cf_t) + [](cdims_t) {
      static Int16Converter c{};
      return &c;
    };
    gf["const int16_t&"] = (cf_t) + [](cdims_t) {
      static ConstInt16RefConverter c{};
      return &c;
    };
    gf["int16_t&"] = (cf_t) + [](cdims_t) {
      static Int16RefConverter c{};
      return &c;
    };
    gf["int32_t"] = (cf_t) + [](cdims_t) {
      static Int32Converter c{};
      return &c;
    };
    gf["const int32_t&"] = (cf_t) + [](cdims_t) {
      static ConstInt32RefConverter c{};
      return &c;
    };
    gf["int32_t&"] = (cf_t) + [](cdims_t) {
      static Int32RefConverter c{};
      return &c;
    };
    gf["uint16_t"] = (cf_t) + [](cdims_t) {
      static UInt16Converter c{};
      return &c;
    };
    gf["const uint16_t&"] = (cf_t) + [](cdims_t) {
      static ConstUInt16RefConverter c{};
      return &c;
    };
    gf["uint16_t&"] = (cf_t) + [](cdims_t) {
      static UInt16RefConverter c{};
      return &c;
    };
    gf["uint32_t"] = (cf_t) + [](cdims_t) {
      static UInt32Converter c{};
      return &c;
    };
    gf["const uint32_t&"] = (cf_t) + [](cdims_t) {
      static ConstUInt32RefConverter c{};
      return &c;
    };
    gf["uint32_t&"] = (cf_t) + [](cdims_t) {
      static UInt32RefConverter c{};
      return &c;
    };
    gf["short"] = (cf_t) + [](cdims_t) {
      static ShortConverter c{};
      return &c;
    };
    gf["const short&"] = (cf_t) + [](cdims_t) {
      static ConstShortRefConverter c{};
      return &c;
    };
    gf["short&"] = (cf_t) + [](cdims_t) {
      static ShortRefConverter c{};
      return &c;
    };
    gf["unsigned short"] = (cf_t) + [](cdims_t) {
      static UShortConverter c{};
      return &c;
    };
    gf["const unsigned short&"] = (cf_t) + [](cdims_t) {
      static ConstUShortRefConverter c{};
      return &c;
    };
    gf["unsigned short&"] = (cf_t) + [](cdims_t) {
      static UShortRefConverter c{};
      return &c;
    };
    gf["int"] = (cf_t) + [](cdims_t) {
      static IntConverter c{};
      return &c;
    };
    gf["int&"] = (cf_t) + [](cdims_t) {
      static IntRefConverter c{};
      return &c;
    };
    gf["const int&"] = (cf_t) + [](cdims_t) {
      static ConstIntRefConverter c{};
      return &c;
    };
    gf["unsigned int"] = (cf_t) + [](cdims_t) {
      static UIntConverter c{};
      return &c;
    };
    gf["const unsigned int&"] = (cf_t) + [](cdims_t) {
      static ConstUIntRefConverter c{};
      return &c;
    };
    gf["unsigned int&"] = (cf_t) + [](cdims_t) {
      static UIntRefConverter c{};
      return &c;
    };
    gf["long"] = (cf_t) + [](cdims_t) {
      static LongConverter c{};
      return &c;
    };
    gf["long&"] = (cf_t) + [](cdims_t) {
      static LongRefConverter c{};
      return &c;
    };
    gf["const long&"] = (cf_t) + [](cdims_t) {
      static ConstLongRefConverter c{};
      return &c;
    };
    gf["unsigned long"] = (cf_t) + [](cdims_t) {
      static ULongConverter c{};
      return &c;
    };
    gf["const unsigned long&"] = (cf_t) + [](cdims_t) {
      static ConstULongRefConverter c{};
      return &c;
    };
    gf["unsigned long&"] = (cf_t) + [](cdims_t) {
      static ULongRefConverter c{};
      return &c;
    };
    gf["long long"] = (cf_t) + [](cdims_t) {
      static LLongConverter c{};
      return &c;
    };
    gf["const long long&"] = (cf_t) + [](cdims_t) {
      static ConstLLongRefConverter c{};
      return &c;
    };
    gf["long long&"] = (cf_t) + [](cdims_t) {
      static LLongRefConverter c{};
      return &c;
    };
    gf["unsigned long long"] = (cf_t) + [](cdims_t) {
      static ULLongConverter c{};
      return &c;
    };
    gf["const unsigned long long&"] = (cf_t) + [](cdims_t) {
      static ConstULLongRefConverter c{};
      return &c;
    };
    gf["unsigned long long&"] = (cf_t) + [](cdims_t) {
      static ULLongRefConverter c{};
      return &c;
    };
 
    gf["float"] = (cf_t) + [](cdims_t) {
      static FloatConverter c{};
      return &c;
    };
    gf["const float&"] = (cf_t) + [](cdims_t) {
      static ConstFloatRefConverter c{};
      return &c;
    };
    gf["float&"] = (cf_t) + [](cdims_t) {
      static FloatRefConverter c{};
      return &c;
    };
    gf["double"] = (cf_t) + [](cdims_t) {
      static DoubleConverter c{};
      return &c;
    };
    gf["double&"] = (cf_t) + [](cdims_t) {
      static DoubleRefConverter c{};
      return &c;
    };
    gf["const double&"] = (cf_t) + [](cdims_t) {
      static ConstDoubleRefConverter c{};
      return &c;
    };
    gf["long double"] = (cf_t) + [](cdims_t) {
      static LDoubleConverter c{};
      return &c;
    };
    gf["const long double&"] = (cf_t) + [](cdims_t) {
      static ConstLDoubleRefConverter c{};
      return &c;
    };
    gf["long double&"] = (cf_t) + [](cdims_t) {
      static LDoubleRefConverter c{};
      return &c;
    };
    gf["std::complex<double>"] =
        (cf_t) + [](cdims_t) { return new ComplexDConverter{}; };
    gf["const std::complex<double>&"] =
        (cf_t) + [](cdims_t) { return new ComplexDConverter{}; };
    gf["void"] = (cf_t) + [](cdims_t) {
      static VoidConverter c{};
      return &c;
    };
 
    // pointer/array factories
    gf["bool ptr"] =
        (cf_t) + [](cdims_t d) { return new BoolArrayConverter{d}; };
    gf["signed char ptr"] =
        (cf_t) + [](cdims_t d) { return new SCharArrayConverter{d}; };
    gf["signed char**"] = (cf_t) + [](cdims_t) {
      return new SCharArrayConverter{{UNKNOWN_SIZE, UNKNOWN_SIZE}};
    };
    gf["const unsigned char*"] =
        (cf_t) + [](cdims_t d) { return new UCharArrayConverter{d}; };
    gf["unsigned char ptr"] =
        (cf_t) + [](cdims_t d) { return new UCharArrayConverter{d}; };
    gf["SCharAsInt*"] = gf["signed char ptr"];
    gf["SCharAsInt[]"] = gf["signed char ptr"];
    gf["UCharAsInt*"] = gf["unsigned char ptr"];
    gf["UCharAsInt[]"] = gf["unsigned char ptr"];
    gf["std::byte ptr"] =
        (cf_t) + [](cdims_t d) { return new ByteArrayConverter{d}; };
    gf["int8_t ptr"] =
        (cf_t) + [](cdims_t d) { return new Int8ArrayConverter{d}; };
    gf["int16_t ptr"] =
        (cf_t) + [](cdims_t d) { return new Int16ArrayConverter{d}; };
    gf["int32_t ptr"] =
        (cf_t) + [](cdims_t d) { return new Int32ArrayConverter{d}; };
    gf["uint8_t ptr"] =
        (cf_t) + [](cdims_t d) { return new UInt8ArrayConverter{d}; };
    gf["uint16_t ptr"] =
        (cf_t) + [](cdims_t d) { return new UInt16ArrayConverter{d}; };
    gf["uint32_t ptr"] =
        (cf_t) + [](cdims_t d) { return new UInt32ArrayConverter{d}; };
    gf["short ptr"] =
        (cf_t) + [](cdims_t d) { return new ShortArrayConverter{d}; };
    gf["unsigned short ptr"] =
        (cf_t) + [](cdims_t d) { return new UShortArrayConverter{d}; };
    gf["int ptr"] = (cf_t) + [](cdims_t d) { return new IntArrayConverter{d}; };
    gf["unsigned int ptr"] =
        (cf_t) + [](cdims_t d) { return new UIntArrayConverter{d}; };
    gf["long ptr"] =
        (cf_t) + [](cdims_t d) { return new LongArrayConverter{d}; };
    gf["unsigned long ptr"] =
        (cf_t) + [](cdims_t d) { return new ULongArrayConverter{d}; };
    gf["long long ptr"] =
        (cf_t) + [](cdims_t d) { return new LLongArrayConverter{d}; };
    gf["unsigned long long ptr"] =
        (cf_t) + [](cdims_t d) { return new ULLongArrayConverter{d}; };
    gf["float ptr"] =
        (cf_t) + [](cdims_t d) { return new FloatArrayConverter{d}; };
    gf["double ptr"] =
        (cf_t) + [](cdims_t d) { return new DoubleArrayConverter{d}; };
    gf["long double ptr"] =
        (cf_t) + [](cdims_t d) { return new LDoubleArrayConverter{d}; };
    gf["std::complex<float> ptr"] =
        (cf_t) + [](cdims_t d) { return new ComplexFArrayConverter{d}; };
    gf["std::complex<double> ptr"] =
        (cf_t) + [](cdims_t d) { return new ComplexDArrayConverter{d}; };
    gf["void*"] =
        (cf_t) + [](cdims_t d) { return new VoidArrayConverter{(bool)d}; };
 
    // aliases
    gf["signed char"] = gf["char"];
    gf["const signed char&"] = gf["const char&"];
    gf["std::byte"] = gf["uint8_t"];
    gf["const std::byte&"] = gf["const uint8_t&"];
    gf["std::byte&"] = gf["uint8_t&"];
    gf["std::int8_t"] = gf["int8_t"];
    gf["const std::int8_t&"] = gf["const int8_t&"];
    gf["std::int8_t&"] = gf["int8_t&"];
    gf["std::uint8_t"] = gf["uint8_t"];
    gf["const std::uint8_t&"] = gf["const uint8_t&"];
    gf["std::uint8_t&"] = gf["uint8_t&"];
    gf["internal_enum_type_t"] = gf["int"];
    gf["internal_enum_type_t&"] = gf["int&"];
    gf["const internal_enum_type_t&"] = gf["const int&"];
    gf["internal_enum_type_t ptr"] = gf["int ptr"];
#ifdef _WIN32
    gf["__int64"] = gf["long long"];
    gf["const __int64&"] = gf["const long long&"];
    gf["__int64&"] = gf["long long&"];
    gf["__int64 ptr"] = gf["long long ptr"];
    gf["unsigned __int64"] = gf["unsigned long long"];
    gf["const unsigned __int64&"] = gf["const unsigned long long&"];
    gf["unsigned __int64&"] = gf["unsigned long long&"];
    gf["unsigned __int64 ptr"] = gf["unsigned long long ptr"];
#endif
    gf[CCOMPLEX_D] = gf["std::complex<double>"];
    gf["const " CCOMPLEX_D "&"] = gf["const std::complex<double>&"];
    gf[CCOMPLEX_F " ptr"] = gf["std::complex<float> ptr"];
    gf[CCOMPLEX_D " ptr"] = gf["std::complex<double> ptr"];
 
    // We always need these converters when cppjit is based on an unpatched
    // ROOT, because the "long long" types are always converted to Long64_t
    // and ULong64_t already at the ROOT Meta level.
    // See
    // https://github.com/root-project/root/issues/15872#issuecomment-2174092763
    gf["Long64_t"] = gf["long long"];
    gf["Long64_t ptr"] = gf["long long ptr"];
    gf["Long64_t&"] = gf["long long&"];
    gf["const Long64_t&"] = gf["const long long&"];
    gf["ULong64_t"] = gf["unsigned long long"];
    gf["ULong64_t ptr"] = gf["unsigned long long ptr"];
    gf["ULong64_t&"] = gf["unsigned long long&"];
    gf["const ULong64_t&"] = gf["const unsigned long long&"];
 
    // factories for special cases
    gf["nullptr_t"] = (cf_t) + [](cdims_t) {
      static NullptrConverter c{};
      return &c;
    };
    gf["const char*"] = (cf_t) + [](cdims_t) { return new CStringConverter{}; };
    gf["const signed char*"] = gf["const char*"];
    gf["const char*&&"] = gf["const char*"];
    gf["const char[]"] =
        (cf_t) + [](cdims_t) { return new CStringConverter{}; };
    gf["char*"] = (cf_t) + [](cdims_t d) {
      return new NonConstCStringConverter{dims2stringsz(d)};
    };
    gf["char[]"] = (cf_t) + [](cdims_t d) {
      return new NonConstCStringArrayConverter{d, true};
    };
    gf["signed char*"] = gf["char*"];
    gf["wchar_t*"] = (cf_t) + [](cdims_t) { return new WCStringConverter{}; };
    // TODO: The libc++ library that is used most prominently by Apple for
    // macOS is using the _Nonnull Clang attribute for some of its string
    // constructors (_LIBCPP_DIAGNOSE_NULLPTR is a preprocessor macro that
    // resolves to _Nullable). The cppjit backend doesn't strip away such Clang
    // attributes, so the wchar_t* converter fails to match. To make the
    // construction of std::wstring work on macOS, we are explicitly creating
    // a converter for the wchar_t*_Nonnull type here, but we should try to
    // find a more general solution for dealing with Clang attributes.
    // [1] https://clang.llvm.org/docs/AttributeReference.html#id656
    // [2]
    // https://github.com/llvm/llvm-project/blob/2078da43e25a4623cab2d0d60decddf709aaea28/libcxx/include/string#L1061
    gf["wchar_t*_Nonnull"] =
        (cf_t) + [](cdims_t) { return new WCStringConverter{}; };
    gf["char16_t*"] = (cf_t) + [](cdims_t) { return new CString16Converter{}; };
    gf["char16_t[]"] = (cf_t) + [](cdims_t d) {
      return new CString16Converter{dims2stringsz(d)};
    };
    gf["char32_t*"] = (cf_t) + [](cdims_t) { return new CString32Converter{}; };
    gf["char32_t[]"] = (cf_t) + [](cdims_t d) {
      return new CString32Converter{dims2stringsz(d)};
    };
    // TODO: the following are handled incorrectly upstream (char16_t** where
    // char16_t* intended)?!
    gf["char16_t**"] = gf["char16_t*"];
    gf["char32_t**"] = gf["char32_t*"];
    gf["const char**"] = (cf_t) + [](cdims_t) {
      return new CStringArrayConverter{{UNKNOWN_SIZE, UNKNOWN_SIZE}, false};
    };
    gf["char**"] = gf["const char**"];
    gf["const char*[]"] =
        (cf_t) + [](cdims_t d) { return new CStringArrayConverter{d, false}; };
    gf["char*[]"] = (cf_t) + [](cdims_t d) {
      return new NonConstCStringArrayConverter{d, false};
    };
    gf["char ptr"] = gf["char*[]"];
    gf["std::basic_string<char>"] =
        (cf_t) + [](cdims_t) { return new STLStringConverter{}; };
    gf["const std::basic_string<char>&"] = gf["std::basic_string<char>"];
    gf["std::basic_string<char>&&"] =
        (cf_t) + [](cdims_t) { return new STLStringMoveConverter{}; };
    gf["const std::basic_string<char> &"] = gf["std::basic_string<char>"];
    gf["std::basic_string<char> &&"] =
        (cf_t) + [](cdims_t) { return new STLStringMoveConverter{}; };
    gf["std::basic_string_view<char>"] =
        (cf_t) + [](cdims_t) { return new STLStringViewConverter{}; };
    gf[STRINGVIEW] = gf["std::basic_string_view<char>"];
    gf["std::basic_string_view<char>&"] = gf["std::basic_string_view<char>"];
    gf["const " STRINGVIEW "&"] = gf["std::basic_string_view<char>"];
    gf["std::basic_string_view<char> &"] = gf["std::basic_string_view<char>"];
    gf["const " STRINGVIEW " &"] = gf["std::basic_string_view<char>"];
    gf["std::wstring"] =
        (cf_t) + [](cdims_t) { return new STLWStringConverter{}; };
    gf[WSTRING1] = gf["std::wstring"];
    gf[WSTRING2] = gf["std::wstring"];
    gf["const std::wstring&"] = gf["std::wstring"];
    gf["const " WSTRING1 "&"] = gf["std::wstring"];
    gf["const " WSTRING2 "&"] = gf["std::wstring"];
    gf["const std::wstring &"] = gf["std::wstring"];
    gf["const " WSTRING1 " &"] = gf["std::wstring"];
    gf["const " WSTRING2 " &"] = gf["std::wstring"];
    // void*& is exempt from the T*& ban: the callee updates the proxy's
    // held pointer through the opaque handle
    gf["void*&"] = (cf_t) + [](cdims_t) {
      static VoidPtrRefConverter c{};
      return &c;
    };
    gf["const void*&"] = gf["void*&"];
    gf["void**"] =
        (cf_t) + [](cdims_t d) { return new VoidPtrPtrConverter{d}; };
    gf["void ptr"] = gf["void**"];
    gf["PyObject*"] = (cf_t) + [](cdims_t) {
      static PyObjectConverter c{};
      return &c;
    };
    gf["_object*"] = gf["PyObject*"];
    gf["FILE*"] = (cf_t) + [](cdims_t) { return new VoidArrayConverter{}; };
  }
} initConvFactories_;
 
} // unnamed namespace