bug#24456: 25.1; [PATCH] Caps-lock doesn't affect interpretation of key chords

[Dima Kogan]

npostavs@users.sourceforge.net writes:

> After applying the patch to emacs-25, I built --with-x-toolkit=lucid and
> --enable-checking; I get an assertion violation when hitting C-n with
> capslock on.

Thanks for testing. I didn't realize that assertions are disabled by
default. Fixed patch attached.


Eli Zaretskii writes:

> Doesn't this mean that ASCII keys will behave differently from
> non-ASCII when Caps Lock is ON?

If you're talking about characters used in non-English languages, then I
really have no idea what the current behavior is, or how to test it. I'm
hoping one of yall who actually use these languages will tell me.

dima

>From 66510839464f0efdc625790f3e64091012408dda Mon Sep 17 00:00:00 2001
From: Dima Kogan <dima@secretsauce.net>
Date: Sat, 17 Sep 2016 23:47:48 -0700
Subject: [PATCH] Caps-lock doesn't affect interpretation of key chords

* src/keyboard.c (make_lispy_event): when a user pressed key-chords the
caps-lock no longer affects the "shift" state of the generated chord.  For
instance Control+s produces C-s regardless of the caps-lock state.  And
Control+Shift+s produces C-S-s regardless of the caps-lock state.
---
 src/keyboard.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/src/keyboard.c b/src/keyboard.c
index b8bc361..cd8413b 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -5417,6 +5417,33 @@ make_lispy_event (struct input_event *event)
          {
            c &= 0377;
            eassert (c == event->code);
+
+            /* Caps-lock shouldn't affect interpretation of key chords:
+               Control+s should produce C-s whether caps-lock is on or
+               not.  And Control+Shift+s should produce C-S-s whether
+               caps-lock is on or not. */
+            if (event->modifiers & ~shift_modifier)
+              {
+                /* this is a key chord: some non-shift modifier is
+                   depressed */
+
+                if ('A' <= c && c <= 'Z' &&
+                    !(event->modifiers & shift_modifier) )
+                  {
+                    /* Got a capital letter without a shift.  The caps
+                       lock is on.   Un-capitalize the letter */
+                    c |= (unsigned)('a' - 'A');
+                  }
+                else if (('a' <= c && c <= 'z') &&
+                         (event->modifiers & shift_modifier) )
+                  {
+                    /* Got a lower-case letter even though shift is
+                       depressed.  The caps lock is on.  Capitalize the
+                       letter */
+                    c &= ~(unsigned)('a' - 'A');
+                  }
+              }
+
            /* Turn ASCII characters into control characters
               when proper.  */
            if (event->modifiers & ctrl_modifier)
-- 
2.9.3