Don't output spurious prefixes in read-char-exclusive

* src/keyboard.c (read_char): Don't touch the echo area if
Vecho_keystrokes is nil.
* src/lread.c (read_filtered_event): Bind echo_keystrokes to nil
to avoid outputting prefixes we're not going to act on anyway
(bug#19718).

2 files changed, 14 insertions, 8 deletions

diff --git a/src/keyboard.c b/src/keyboard.c
index 441c23e10c7..9242e8dc624 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -3059,12 +3059,13 @@ read_char (int commandflag, Lisp_Object map,
 
   /* Now wipe the echo area, except for help events which do their
      own stuff with the echo area.  */
-  if (!CONSP (c)
-      || (!(EQ (Qhelp_echo, XCAR (c)))
-          && !(EQ (Qswitch_frame, XCAR (c)))
-          /* Don't wipe echo area for select window events: These might
-             get delayed via `mouse-autoselect-window' (Bug#11304).  */
-          && !(EQ (Qselect_window, XCAR (c)))))
+  if (!NILP (Vecho_keystrokes)
+      && (!CONSP (c)
+          || (!(EQ (Qhelp_echo, XCAR (c)))
+              && !(EQ (Qswitch_frame, XCAR (c)))
+              /* Don't wipe echo area for select window events: These might
+                 get delayed via `mouse-autoselect-window' (Bug#11304).  */
+              && !(EQ (Qselect_window, XCAR (c))))))
     {
       if (!NILP (echo_area_buffer[0]))
         {
diff --git a/src/lread.c b/src/lread.c
index 9910db27de7..ec54d2d81ad 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -705,8 +705,13 @@ read_filtered_event (bool no_switch_frame, bool ascii_required,
   /* Read until we get an acceptable event.  */
  retry:
   do
-    val = read_char (0, Qnil, (input_method ? Qnil : Qt), 0,
-                     NUMBERP (seconds) ? &end_time : NULL);
+    {
+      ptrdiff_t count = SPECPDL_INDEX ();
+      specbind (Qecho_keystrokes, Qnil);
+      val = read_char (0, Qnil, (input_method ? Qnil : Qt), 0,
+                       NUMBERP (seconds) ? &end_time : NULL);
+      unbind_to (count, Qnil);
+    }
   while (FIXNUMP (val) && XFIXNUM (val) == -2); /* wrong_kboard_jmpbuf */
 
   if (BUFFERP (val))