Restore the PyExc_RecursionErrorInst public symbol

00292-restore-PyExc_RecursionErrorInst-symbol.patch

@@ -0,0 +1,106 @@
+diff --git a/Doc/whatsnew/3.6.rst b/Doc/whatsnew/3.6.rst
+index 847b50140a6..570dc3ed6fe 100644
+--- a/Doc/whatsnew/3.6.rst
++++ b/Doc/whatsnew/3.6.rst
+@@ -1852,10 +1852,10 @@ Build and C API Changes
+ * The :c:func:`PyUnicode_FSConverter` and :c:func:`PyUnicode_FSDecoder`
+   functions will now accept :term:`path-like objects <path-like object>`.
+ 
+-* The ``PyExc_RecursionErrorInst`` singleton that was part of the public API
+-  has been removed as its members being never cleared may cause a segfault
+-  during finalization of the interpreter. Contributed by Xavier de Gaye in
+-  :issue:`22898` and :issue:`30697`.
++* The ``PyExc_RecursionErrorInst`` singleton is not used anymore as its members
++  being never cleared may cause a segfault during finalization of the
++  interpreter. Contributed by Xavier de Gaye in :issue:`22898` and
++  :issue:`30697`.
+ 
+ 
+ Other Improvements
+diff --git a/Include/pyerrors.h b/Include/pyerrors.h
+index c28c1373f82..8c1dbc5047b 100644
+--- a/Include/pyerrors.h
++++ b/Include/pyerrors.h
+@@ -219,6 +219,8 @@ PyAPI_DATA(PyObject *) PyExc_IOError;
+ PyAPI_DATA(PyObject *) PyExc_WindowsError;
+ #endif
+ 
++PyAPI_DATA(PyObject *) PyExc_RecursionErrorInst;
++
+ /* Predefined warning categories */
+ PyAPI_DATA(PyObject *) PyExc_Warning;
+ PyAPI_DATA(PyObject *) PyExc_UserWarning;
+diff --git a/Misc/NEWS.d/next/C API/2017-12-20-15-23-06.bpo-30697.v9FmgG.rst b/Misc/NEWS.d/next/C API/2017-12-20-15-23-06.bpo-30697.v9FmgG.rst
+new file mode 100644
+index 00000000000..28f74ad4f30
+--- /dev/null
++++ b/Misc/NEWS.d/next/C API/2017-12-20-15-23-06.bpo-30697.v9FmgG.rst	
+@@ -0,0 +1 @@
++Restore PyExc_RecursionErrorInst in 3.6
+diff --git a/Objects/exceptions.c b/Objects/exceptions.c
+index df4899372a5..271e293e325 100644
+--- a/Objects/exceptions.c
++++ b/Objects/exceptions.c
+@@ -2430,6 +2430,12 @@ SimpleExtendsException(PyExc_Warning, ResourceWarning,
+ 
+ 
+ 
++/* Pre-computed RecursionError instance for when recursion depth is reached.
++   Meant to be used when normalizing the exception for exceeding the recursion
++   depth will cause its own infinite recursion.
++*/
++PyObject *PyExc_RecursionErrorInst = NULL;
++
+ #define PRE_INIT(TYPE) \
+     if (!(_PyExc_ ## TYPE.tp_flags & Py_TPFLAGS_READY)) { \
+         if (PyType_Ready(&_PyExc_ ## TYPE) < 0) \
+@@ -2691,11 +2697,37 @@ _PyExc_Init(PyObject *bltinmod)
+     ADD_ERRNO(TimeoutError, ETIMEDOUT);
+ 
+     preallocate_memerrors();
++
++    if (!PyExc_RecursionErrorInst) {
++        PyExc_RecursionErrorInst = BaseException_new(&_PyExc_RecursionError, NULL, NULL);
++        if (!PyExc_RecursionErrorInst)
++            Py_FatalError("Cannot pre-allocate RecursionError instance for "
++                            "recursion errors");
++        else {
++            PyBaseExceptionObject *err_inst =
++                (PyBaseExceptionObject *)PyExc_RecursionErrorInst;
++            PyObject *args_tuple;
++            PyObject *exc_message;
++            exc_message = PyUnicode_FromString("maximum recursion depth exceeded");
++            if (!exc_message)
++                Py_FatalError("cannot allocate argument for RecursionError "
++                                "pre-allocation");
++            args_tuple = PyTuple_Pack(1, exc_message);
++            if (!args_tuple)
++                Py_FatalError("cannot allocate tuple for RecursionError "
++                                "pre-allocation");
++            Py_DECREF(exc_message);
++            if (BaseException_init(err_inst, args_tuple, NULL))
++                Py_FatalError("init of pre-allocated RecursionError failed");
++            Py_DECREF(args_tuple);
++        }
++    }
+ }
+ 
+ void
+ _PyExc_Fini(void)
+ {
++    Py_CLEAR(PyExc_RecursionErrorInst);
+     free_preallocated_memerrors();
+     Py_CLEAR(errnomap);
+ }
+diff --git a/PC/python3.def b/PC/python3.def
+index 4fc4a6814ee..ff70718fc37 100644
+--- a/PC/python3.def
++++ b/PC/python3.def
+@@ -224,6 +224,7 @@ EXPORTS
+   PyExc_PermissionError=python36.PyExc_PermissionError DATA
+   PyExc_ProcessLookupError=python36.PyExc_ProcessLookupError DATA
+   PyExc_RecursionError=python36.PyExc_RecursionError DATA
++  PyExc_RecursionErrorInst=python36.PyExc_RecursionErrorInst DATA
+   PyExc_ReferenceError=python36.PyExc_ReferenceError DATA
+   PyExc_ResourceWarning=python36.PyExc_ResourceWarning DATA
+   PyExc_RuntimeError=python36.PyExc_RuntimeError DATA