bpo-36523: Add docstring to io.IOBase.writelines (GH-12683)

(cherry picked from commit ab86521a9d9999731e39bd9056420bb7774fd144)

2 files changed, 12 insertions, 3 deletions

diff --git a/Modules/_io/clinic/iobase.c.h b/Modules/_io/clinic/iobase.c.h
index e6f72cd5ff..66836bfdf4 100644
--- a/Modules/_io/clinic/iobase.c.h
+++ b/Modules/_io/clinic/iobase.c.h
@@ -230,7 +230,11 @@ exit:
 PyDoc_STRVAR(_io__IOBase_writelines__doc__,
 "writelines($self, lines, /)\n"
 "--\n"
-"\n");
+"\n"
+"Write a list of lines to stream.\n"
+"\n"
+"Line separators are not added, so it is usual for each of the\n"
+"lines provided to have a line separator at the end.");
 
 #define _IO__IOBASE_WRITELINES_METHODDEF    \
     {"writelines", (PyCFunction)_io__IOBase_writelines, METH_O, _io__IOBase_writelines__doc__},
@@ -279,4 +283,4 @@ _io__RawIOBase_readall(PyObject *self, PyObject *Py_UNUSED(ignored))
 {
     return _io__RawIOBase_readall_impl(self);
 }
-/*[clinic end generated code: output=64989ec3dbf44a7c input=a9049054013a1b77]*/
+/*[clinic end generated code: output=6f8d078401fb9d48 input=a9049054013a1b77]*/
diff --git a/Modules/_io/iobase.c b/Modules/_io/iobase.c
index 5b71732ef1..6995c1570c 100644
--- a/Modules/_io/iobase.c
+++ b/Modules/_io/iobase.c
@@ -738,11 +738,16 @@ _io__IOBase_readlines_impl(PyObject *self, Py_ssize_t hint)
 _io._IOBase.writelines
     lines: object
     /
+
+Write a list of lines to stream.
+
+Line separators are not added, so it is usual for each of the
+lines provided to have a line separator at the end.
 [clinic start generated code]*/
 
 static PyObject *
 _io__IOBase_writelines(PyObject *self, PyObject *lines)
-/*[clinic end generated code: output=976eb0a9b60a6628 input=432e729a8450b3cb]*/
+/*[clinic end generated code: output=976eb0a9b60a6628 input=cac3fc8864183359]*/
 {
     PyObject *iter, *res;