bpo-45296: Fix exit/quit message on Windows (GH-28577) (GH-28601)

IDLE recognizes Ctrl-D, as on other systems, instead of Ctrl-Z.
(cherry picked from commit e649e06)

Co-authored-by: Terry Jan Reedy <[email protected]>

Author: miss-islington

Lib/idlelib/pyshell.py

@@ -60,6 +60,13 @@
 HOST = '127.0.0.1' # python execution server on localhost loopback
 PORT = 0  # someday pass in host, port for remote debug capability
 
+try:  # In case IDLE started with -n.
+    eof = 'Ctrl-D (end-of-file)'
+    exit.eof = eof
+    quit.eof = eof
+except NameError: # In case python started with -S.
+    pass
+
 # Override warnings module to write to warning_stream.  Initialize to send IDLE
 # internal warnings to the console.  ScriptBinding.check_syntax() will
 # temporarily redirect the stream to the shell window to display warnings when

Lib/idlelib/run.py

@@ -39,6 +39,13 @@
 
 LOCALHOST = '127.0.0.1'
 
+try:
+    eof = 'Ctrl-D (end-of-file)'
+    exit.eof = eof
+    quit.eof = eof
+except NameError: # In case subprocess started with -S (maybe in future).
+    pass
+
 
 def idle_formatwarning(message, category, filename, lineno, line=None):
     """Format warnings the IDLE way."""

Misc/NEWS.d/next/IDLE/2021-09-27-01-21-59.bpo-45296.9H8rdY.rst

@@ -0,0 +1,2 @@
+On Windows, change exit/quit message to suggest Ctrl-D, which works, instead
+of <Ctrl-Z Return>, which does not work in IDLE.