Add C++ support (#18)

* pythoncapi_compat.h uses nullptr and reinterpret_cast<> on C++
* Add tests/test_pythoncapi_compat_cppext.cpp

Author: vstinner

docs/api.rst

@@ -5,7 +5,12 @@ pythoncapi_compat.h API
 The ``pythoncapi_compat.h`` header file provides implementations of recent
 functions for old Python versions.
 
-It supports Python 3.5 to Python 3.11, Python 2.7, PyPy 3.6 and PyPy 2.7.
+Supported Python versions:
+
+* Python 2.7, Python 3.5 - 3.11
+* PyPy 2.7, 3.6 and 3.7
+
+C++ is supported on Python 3.6 and newer.
 
 A C99 subset is required, like ``static inline`` functions: see `PEP 7
 <https://www.python.org/dev/peps/pep-0007/>`_.  ISO C90 is partially supported

docs/changelog.rst

@@ -1,6 +1,9 @@
 Changelog
 =========
 
+* 2022-02-09: ``pythoncapi_compat.h`` now supports C++ on Python 3.6 and newer:
+  use ``nullptr`` and ``reinterpret_cast<type>`` cast on C++, and use ``NULL``
+  and ``(type)`` cast on C.
 * 2021-10-15: Add ``PyThreadState_EnterTracing()`` and
   ``PyThreadState_LeaveTracing()``.
 * 2021-04-09: Add ``Py_Is()``, ``Py_IsNone()``, ``Py_IsTrue()``,

pythoncapi_compat.h

@@ -27,24 +27,34 @@ extern "C" {
 // the inline keyword in C (only in C++): use __inline instead.
 #if (defined(_MSC_VER) && _MSC_VER < 1900 \
      && !defined(__cplusplus) && !defined(inline))
-#  define inline __inline
-#  define PYTHONCAPI_COMPAT_MSC_INLINE
-   // These two macros are undefined at the end of this file
+#  define PYCAPI_COMPAT_INLINE(TYPE static __inline TYPE
+#else
+#  define PYCAPI_COMPAT_STATIC_INLINE(TYPE) static inline TYPE
 #endif
 
 
+// C++ compatibility
+#ifdef __cplusplus
+#  define PYCAPI_COMPAT_CAST(TYPE, EXPR) reinterpret_cast<TYPE>(EXPR)
+#  define PYCAPI_COMPAT_NULL nullptr
+#else
+#  define PYCAPI_COMPAT_CAST(TYPE, EXPR) (TYPE)(EXPR)
+#  define PYCAPI_COMPAT_NULL NULL
+#endif
+
 // Cast argument to PyObject* type.
 #ifndef _PyObject_CAST
-#  define _PyObject_CAST(op) ((PyObject*)(op))
+#  define _PyObject_CAST(op) PYCAPI_COMPAT_CAST(PyObject*, op)
 #endif
 #ifndef _PyObject_CAST_CONST
-#  define _PyObject_CAST_CONST(op) ((const PyObject*)(op))
+#  define _PyObject_CAST_CONST(op) PYCAPI_COMPAT_CAST(const PyObject*, op)
 #endif
 
 
 // bpo-42262 added Py_NewRef() to Python 3.10.0a3
 #if PY_VERSION_HEX < 0x030A00A3 && !defined(Py_NewRef)
-static inline PyObject* _Py_NewRef(PyObject *obj)
+PYCAPI_COMPAT_STATIC_INLINE(PyObject*)
+_Py_NewRef(PyObject *obj)
 {
     Py_INCREF(obj);
     return obj;
@@ -55,7 +65,8 @@ static inline PyObject* _Py_NewRef(PyObject *obj)
 
 // bpo-42262 added Py_XNewRef() to Python 3.10.0a3
 #if PY_VERSION_HEX < 0x030A00A3 && !defined(Py_XNewRef)
-static inline PyObject* _Py_XNewRef(PyObject *obj)
+PYCAPI_COMPAT_STATIC_INLINE(PyObject*)
+_Py_XNewRef(PyObject *obj)
 {
     Py_XINCREF(obj);
     return obj;
@@ -66,7 +77,8 @@ static inline PyObject* _Py_XNewRef(PyObject *obj)
 
 // See https://bugs.python.org/issue42522
 #if !defined(_Py_StealRef)
-static inline PyObject* __Py_StealRef(PyObject *obj)
+PYCAPI_COMPAT_STATIC_INLINE(PyObject*)
+__Py_StealRef(PyObject *obj)
 {
     Py_DECREF(obj);
     return obj;
@@ -77,7 +89,8 @@ static inline PyObject* __Py_StealRef(PyObject *obj)
 
 // See https://bugs.python.org/issue42522
 #if !defined(_Py_XStealRef)
-static inline PyObject* __Py_XStealRef(PyObject *obj)
+PYCAPI_COMPAT_STATIC_INLINE(PyObject*)
+__Py_XStealRef(PyObject *obj)
 {
     Py_XDECREF(obj);
     return obj;
@@ -88,7 +101,8 @@ static inline PyObject* __Py_XStealRef(PyObject *obj)
 
 // bpo-39573 added Py_SET_REFCNT() to Python 3.9.0a4
 #if PY_VERSION_HEX < 0x030900A4 && !defined(Py_SET_REFCNT)
-static inline void _Py_SET_REFCNT(PyObject *ob, Py_ssize_t refcnt)
+PYCAPI_COMPAT_STATIC_INLINE(void)
+_Py_SET_REFCNT(PyObject *ob, Py_ssize_t refcnt)
 {
     ob->ob_refcnt = refcnt;
 }
@@ -133,7 +147,7 @@ static inline void _Py_SET_REFCNT(PyObject *ob, Py_ssize_t refcnt)
 
 // bpo-39573 added Py_SET_TYPE() to Python 3.9.0a4
 #if PY_VERSION_HEX < 0x030900A4 && !defined(Py_SET_TYPE)
-static inline void
+PYCAPI_COMPAT_STATIC_INLINE(void)
 _Py_SET_TYPE(PyObject *ob, PyTypeObject *type)
 {
     ob->ob_type = type;
@@ -144,7 +158,7 @@ _Py_SET_TYPE(PyObject *ob, PyTypeObject *type)
 
 // bpo-39573 added Py_SET_SIZE() to Python 3.9.0a4
 #if PY_VERSION_HEX < 0x030900A4 && !defined(Py_SET_SIZE)
-static inline void
+PYCAPI_COMPAT_STATIC_INLINE(void)
 _Py_SET_SIZE(PyVarObject *ob, Py_ssize_t size)
 {
     ob->ob_size = size;
@@ -155,85 +169,88 @@ _Py_SET_SIZE(PyVarObject *ob, Py_ssize_t size)
 
 // bpo-40421 added PyFrame_GetCode() to Python 3.9.0b1
 #if PY_VERSION_HEX < 0x030900B1
-static inline PyCodeObject*
+PYCAPI_COMPAT_STATIC_INLINE(PyCodeObject*)
 PyFrame_GetCode(PyFrameObject *frame)
 {
-    assert(frame != NULL);
-    assert(frame->f_code != NULL);
-    return (PyCodeObject*)Py_NewRef(frame->f_code);
+    assert(frame != PYCAPI_COMPAT_NULL);
+    assert(frame->f_code != PYCAPI_COMPAT_NULL);
+    return PYCAPI_COMPAT_CAST(PyCodeObject*, Py_NewRef(frame->f_code));
 }
 #endif
 
-static inline PyCodeObject*
+PYCAPI_COMPAT_STATIC_INLINE(PyCodeObject*)
 _PyFrame_GetCodeBorrow(PyFrameObject *frame)
 {
-    return (PyCodeObject *)_Py_StealRef(PyFrame_GetCode(frame));
+    return PYCAPI_COMPAT_CAST(PyCodeObject *,
+                              _Py_StealRef(PyFrame_GetCode(frame)));
 }
 
 
 // bpo-40421 added PyFrame_GetCode() to Python 3.9.0b1
 #if PY_VERSION_HEX < 0x030900B1 && !defined(PYPY_VERSION)
-static inline PyFrameObject*
+PYCAPI_COMPAT_STATIC_INLINE(PyFrameObject*)
 PyFrame_GetBack(PyFrameObject *frame)
 {
-    assert(frame != NULL);
-    return (PyFrameObject*)Py_XNewRef(frame->f_back);
+    assert(frame != PYCAPI_COMPAT_NULL);
+    return PYCAPI_COMPAT_CAST(PyFrameObject*, Py_XNewRef(frame->f_back));
 }
 #endif
 
 #if !defined(PYPY_VERSION)
-static inline PyFrameObject*
+PYCAPI_COMPAT_STATIC_INLINE(PyFrameObject*)
 _PyFrame_GetBackBorrow(PyFrameObject *frame)
 {
-    return (PyFrameObject *)_Py_XStealRef(PyFrame_GetBack(frame));
+    return PYCAPI_COMPAT_CAST(PyFrameObject *,
+                                  _Py_XStealRef(PyFrame_GetBack(frame)));
 }
 #endif
 
 
 // bpo-39947 added PyThreadState_GetInterpreter() to Python 3.9.0a5
 #if PY_VERSION_HEX < 0x030900A5
-static inline PyInterpreterState *
+PYCAPI_COMPAT_STATIC_INLINE(PyInterpreterState *)
 PyThreadState_GetInterpreter(PyThreadState *tstate)
 {
-    assert(tstate != NULL);
+    assert(tstate != PYCAPI_COMPAT_NULL);
     return tstate->interp;
 }
 #endif
 
 
 // bpo-40429 added PyThreadState_GetFrame() to Python 3.9.0b1
 #if PY_VERSION_HEX < 0x030900B1 && !defined(PYPY_VERSION)
-static inline PyFrameObject*
+PYCAPI_COMPAT_STATIC_INLINE(PyFrameObject*)
 PyThreadState_GetFrame(PyThreadState *tstate)
 {
-    assert(tstate != NULL);
-    return (PyFrameObject *)Py_XNewRef(tstate->frame);
+    assert(tstate != PYCAPI_COMPAT_NULL);
+    return PYCAPI_COMPAT_CAST(PyFrameObject *, Py_XNewRef(tstate->frame));
 }
 #endif
 
 #if !defined(PYPY_VERSION)
-static inline PyFrameObject*
+PYCAPI_COMPAT_STATIC_INLINE(PyFrameObject*)
 _PyThreadState_GetFrameBorrow(PyThreadState *tstate)
 {
-    return (PyFrameObject *)_Py_XStealRef(PyThreadState_GetFrame(tstate));
+    return PYCAPI_COMPAT_CAST(PyFrameObject*,
+                              _Py_XStealRef(PyThreadState_GetFrame(tstate)));
 }
 #endif
 
 
 // bpo-39947 added PyInterpreterState_Get() to Python 3.9.0a5
 #if PY_VERSION_HEX < 0x030900A5
-static inline PyInterpreterState *
+PYCAPI_COMPAT_STATIC_INLINE(PyInterpreterState*)
 PyInterpreterState_Get(void)
 {
     PyThreadState *tstate;
     PyInterpreterState *interp;
 
     tstate = PyThreadState_GET();
-    if (tstate == NULL) {
+    if (tstate == PYCAPI_COMPAT_NULL) {
         Py_FatalError("GIL released (tstate is NULL)");
     }
     interp = tstate->interp;
-    if (interp == NULL) {
+    if (interp == PYCAPI_COMPAT_NULL) {
         Py_FatalError("no current interpreter");
     }
     return interp;
@@ -243,17 +260,18 @@ PyInterpreterState_Get(void)
 
 // bpo-39947 added PyInterpreterState_Get() to Python 3.9.0a6
 #if 0x030700A1 <= PY_VERSION_HEX && PY_VERSION_HEX < 0x030900A6 && !defined(PYPY_VERSION)
-static inline uint64_t
+PYCAPI_COMPAT_STATIC_INLINE(uint64_t)
 PyThreadState_GetID(PyThreadState *tstate)
 {
-    assert(tstate != NULL);
+    assert(tstate != PYCAPI_COMPAT_NULL);
     return tstate->id;
 }
 #endif
 
 // bpo-43760 added PyThreadState_EnterTracing() to Python 3.11.0a2
 #if PY_VERSION_HEX < 0x030B00A2 && !defined(PYPY_VERSION)
-static inline void PyThreadState_EnterTracing(PyThreadState *tstate)
+PYCAPI_COMPAT_STATIC_INLINE(void)
+PyThreadState_EnterTracing(PyThreadState *tstate)
 {
     tstate->tracing++;
 #if PY_VERSION_HEX >= 0x030A00A1
@@ -266,10 +284,11 @@ static inline void PyThreadState_EnterTracing(PyThreadState *tstate)
 
 // bpo-43760 added PyThreadState_LeaveTracing() to Python 3.11.0a2
 #if PY_VERSION_HEX < 0x030B00A2 && !defined(PYPY_VERSION)
-static inline void PyThreadState_LeaveTracing(PyThreadState *tstate)
+PYCAPI_COMPAT_STATIC_INLINE(void)
+PyThreadState_LeaveTracing(PyThreadState *tstate)
 {
-    int use_tracing = (tstate->c_tracefunc != NULL
-                       || tstate->c_profilefunc != NULL);
+    int use_tracing = (tstate->c_tracefunc != PYCAPI_COMPAT_NULL
+                       || tstate->c_profilefunc != PYCAPI_COMPAT_NULL);
     tstate->tracing--;
 #if PY_VERSION_HEX >= 0x030A00A1
     tstate->cframe->use_tracing = use_tracing;
@@ -282,7 +301,7 @@ static inline void PyThreadState_LeaveTracing(PyThreadState *tstate)
 
 // bpo-37194 added PyObject_CallNoArgs() to Python 3.9.0a1
 #if PY_VERSION_HEX < 0x030900A1
-static inline PyObject*
+PYCAPI_COMPAT_STATIC_INLINE(PyObject*)
 PyObject_CallNoArgs(PyObject *func)
 {
     return PyObject_CallFunctionObjArgs(func, NULL);
@@ -293,7 +312,7 @@ PyObject_CallNoArgs(PyObject *func)
 // bpo-39245 made PyObject_CallOneArg() public (previously called
 // _PyObject_CallOneArg) in Python 3.9.0a4
 #if PY_VERSION_HEX < 0x030900A4
-static inline PyObject*
+PYCAPI_COMPAT_STATIC_INLINE(PyObject*)
 PyObject_CallOneArg(PyObject *func, PyObject *arg)
 {
     return PyObject_CallFunctionObjArgs(func, arg, NULL);
@@ -303,7 +322,7 @@ PyObject_CallOneArg(PyObject *func, PyObject *arg)
 
 // bpo-1635741 added PyModule_AddObjectRef() to Python 3.10.0a3
 #if PY_VERSION_HEX < 0x030A00A3
-static inline int
+PYCAPI_COMPAT_STATIC_INLINE(int)
 PyModule_AddObjectRef(PyObject *module, const char *name, PyObject *value)
 {
     int res;
@@ -319,7 +338,7 @@ PyModule_AddObjectRef(PyObject *module, const char *name, PyObject *value)
 
 // bpo-40024 added PyModule_AddType() to Python 3.9.0a5
 #if PY_VERSION_HEX < 0x030900A5
-static inline int
+PYCAPI_COMPAT_STATIC_INLINE(int)
 PyModule_AddType(PyObject *module, PyTypeObject *type)
 {
     const char *name, *dot;
@@ -330,21 +349,21 @@ PyModule_AddType(PyObject *module, PyTypeObject *type)
 
     // inline _PyType_Name()
     name = type->tp_name;
-    assert(name != NULL);
+    assert(name != PYCAPI_COMPAT_NULL);
     dot = strrchr(name, '.');
-    if (dot != NULL) {
+    if (dot != PYCAPI_COMPAT_NULL) {
         name = dot + 1;
     }
 
-    return PyModule_AddObjectRef(module, name, (PyObject *)type);
+    return PyModule_AddObjectRef(module, name, _PyObject_CAST(type));
 }
 #endif
 
 
 // bpo-40241 added PyObject_GC_IsTracked() to Python 3.9.0a6.
 // bpo-4688 added _PyObject_GC_IS_TRACKED() to Python 2.7.0a2.
 #if PY_VERSION_HEX < 0x030900A6 && !defined(PYPY_VERSION)
-static inline int
+PYCAPI_COMPAT_STATIC_INLINE(int)
 PyObject_GC_IsTracked(PyObject* obj)
 {
     return (PyObject_IS_GC(obj) && _PyObject_GC_IS_TRACKED(obj));
@@ -354,17 +373,18 @@ PyObject_GC_IsTracked(PyObject* obj)
 // bpo-40241 added PyObject_GC_IsFinalized() to Python 3.9.0a6.
 // bpo-18112 added _PyGCHead_FINALIZED() to Python 3.4.0 final.
 #if PY_VERSION_HEX < 0x030900A6 && PY_VERSION_HEX >= 0x030400F0 && !defined(PYPY_VERSION)
-static inline int
+PYCAPI_COMPAT_STATIC_INLINE(int)
 PyObject_GC_IsFinalized(PyObject *obj)
 {
-    return (PyObject_IS_GC(obj) && _PyGCHead_FINALIZED((PyGC_Head *)(obj)-1));
+    PyGC_Head *gc = PYCAPI_COMPAT_CAST(PyGC_Head *, obj) - 1;
+    return (PyObject_IS_GC(obj) && _PyGCHead_FINALIZED(gc));
 }
 #endif
 
 
 // bpo-39573 added Py_IS_TYPE() to Python 3.9.0a4
 #if PY_VERSION_HEX < 0x030900A4 && !defined(Py_IS_TYPE)
-static inline int
+PYCAPI_COMPAT_STATIC_INLINE(int)
 _Py_IS_TYPE(const PyObject *ob, const PyTypeObject *type) {
     return ob->ob_type == type;
 }
@@ -382,11 +402,6 @@ _Py_IS_TYPE(const PyObject *ob, const PyTypeObject *type) {
 #endif
 
 
-#ifdef PYTHONCAPI_COMPAT_MSC_INLINE
-#  undef inline
-#  undef PYTHONCAPI_COMPAT_MSC_INLINE
-#endif
-
 #ifdef __cplusplus
 }
 #endif

runtests.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/python3 -u
 """
 Run the test suite on multiple Python versions.