[3.8] bpo-37250: put back tp_print for backwards compatibility (GH-14193)
This is a 3.8-only compatibility measure for third-party Cython-based sdists.
https://bugs.python.org/issue37250
diff --git a/Include/cpython/object.h b/Include/cpython/object.h
index a65aaf6..5a0ac4a 100644
--- a/Include/cpython/object.h
+++ b/Include/cpython/object.h
@@ -256,6 +256,9 @@
destructor tp_finalize;
vectorcallfunc tp_vectorcall;
+ /* bpo-37250: kept for backwards compatibility in CPython 3.8 only */
+ Py_DEPRECATED(3.8) int (*tp_print)(PyObject *, FILE *, int);
+
#ifdef COUNT_ALLOCS
/* these must be last and never explicitly initialized */
Py_ssize_t tp_allocs;
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 49f2722..a7df7a2 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -1275,7 +1275,7 @@
check((1,2,3), vsize('') + 3*self.P)
# type
# static type: PyTypeObject
- fmt = 'P2nPI13Pl4Pn9Pn11PIPP'
+ fmt = 'P2nPI13Pl4Pn9Pn11PIPPP'
if hasattr(sys, 'getcounts'):
fmt += '3n2P'
s = vsize(fmt)
diff --git a/Misc/NEWS.d/next/C API/2019-06-12-11-45-36.bpo-37221.RhP1E7.rst b/Misc/NEWS.d/next/C API/2019-06-12-11-45-36.bpo-37221.RhP1E7.rst
new file mode 100644
index 0000000..96b61de
--- /dev/null
+++ b/Misc/NEWS.d/next/C API/2019-06-12-11-45-36.bpo-37221.RhP1E7.rst
@@ -0,0 +1,4 @@
+``tp_print`` is put back at the end of the ``PyTypeObject`` structure
+to restore support for old code (in particular generated by Cython)
+setting ``tp_print = 0``.
+Note that ``tp_print`` will be removed entirely in Python 3.9.
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index 07aadea..1042ea7 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -6008,6 +6008,10 @@
Py_INCREF(&MyList_Type);
PyModule_AddObject(m, "MyList", (PyObject *)&MyList_Type);
+ /* bpo-37250: old Cython code sets tp_print to 0, we check that
+ * this doesn't break anything. */
+ MyList_Type.tp_print = 0;
+
if (PyType_Ready(&MethodDescriptorBase_Type) < 0)
return NULL;
Py_INCREF(&MethodDescriptorBase_Type);