[3.6] bpo-31232: Backport custom print rshift message (GH-3155)

bpo-30721 added a "Did you mean ...?" suggestion to rshift
TypeError messages that triggers when the LHS is a Python
C function called "print".

Since this custom error message is expected to be triggered
primarily by attempts to use Python 2 print redirection syntax
in Python 3, and is incredibly unlikely to be encountered
otherwise, it is also being backported to the next 3.6
maintenance release.

Initial patch by Sanyam Khurana.

1 files changed, 15 insertions, 0 deletions

diff --git a/Objects/abstract.c b/Objects/abstract.c
index 38de774..6c6c86c 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -809,6 +809,21 @@ binary_op(PyObject *v, PyObject *w, const int op_slot, const char *op_name)
     PyObject *result = binary_op1(v, w, op_slot);
     if (result == Py_NotImplemented) {
         Py_DECREF(result);
+
+        if (op_slot == NB_SLOT(nb_rshift) &&
+            PyCFunction_Check(v) &&
+            strcmp(((PyCFunctionObject *)v)->m_ml->ml_name, "print") == 0)
+        {
+            PyErr_Format(PyExc_TypeError,
+                "unsupported operand type(s) for %.100s: "
+                "'%.100s' and '%.100s'. Did you mean \"print(<message>, "
+                "file=<output_stream>)\"?",
+                op_name,
+                v->ob_type->tp_name,
+                w->ob_type->tp_name);
+            return NULL;
+        }
+
         return binop_type_error(v, w, op_name);
     }
     return result;