bug#65068: 29.1; xkb-interception interaction causes problems with key combinations

[Po Lu]

Alexander Prähauser <alexander.praehauser@gmx.at> writes:

> It does seem to register the correct level shifts now, but it seems to
> evaluate each key immediately after having been
> pressed. For instance, when I press Space-CapsLock-U, this should
> evaluate to C-; and it does, but this is the output
> I'm receiving in-between:
>
> <Control_R> is undefined
> C-' is undefined
> C-; is undefined
>
> Po Lu [2023-08-24 Thu 17:56] wrote:
>
>> Alexander Prähauser <alexander.praehauser@gmx.at> writes:
>>
>>> The significance of the U-key is that when I press Space-CapsLock-U
>>> (or any other key, I think), it doesn't send the signal
>>> that is configured by xkb but the corresponding key of the default
>>> English keymap (u for the U-key), which really
>>> shouldn't happen. Anyway, here the output after pressing the
>>> sequence
>>> you wanted:
>>>
>>> keycode: 48, keysym: 65027, 0
>>> keycode: 192, keysym: 269025093, 0
>>> keycode: 37, keysym: 65507, 0
>>> keycode: 37, keysym: 65507, 0 <- Control_R
>>> keycode: 48, keysym: 65027, 0 <- AC11, ISO_Level3_Shift
>>> keycode: 192, keysym: 269025093, <- XF86Launch5
>>
>> This attests to Emacs registering the keysyms you meant it to. If
>> ISO_Level3_Shift is registered as a modifier key, it should not be
>> translated into keyboard input afterwards, let alone the original
>> apostrophe symbol.
>>
>> Does this patch resolve your problems with typing level 3 characters
>> coupled with Control?
>>
>> diff --git a/src/xterm.c b/src/xterm.c
>> index 6a1642ff56e..7391041ea0c 100644
>> --- a/src/xterm.c
>> +++ b/src/xterm.c
>> @@ -23734,6 +23734,7 @@ handle_one_xevent (struct x_display_info
>> *dpyinfo,
>>            ptrdiff_t i;
>>            unsigned int old_state;
>>            struct xi_device_t *device, *source;
>> +          bool is_modifier_key;
>>            coding = Qlatin_1;
>>  @@ -24175,17 +24176,7 @@ handle_one_xevent (struct x_display_info
>> *dpyinfo,
>>                     /* Any "vendor-specific" key is ok.  */
>>                     || (keysym & (1 << 28))
>>                     || (keysym != NoSymbol && nbytes == 0))
>> -                  && ! (IsModifierKey (keysym)
>> -                        /* The symbols from XK_ISO_Lock
>> -                           to XK_ISO_Last_Group_Lock
>> -                           don't have real modifiers but
>> -                           should be treated similarly to
>> -                           Mode_switch by Emacs. */
>> -#if defined XK_ISO_Lock && defined XK_ISO_Last_Group_Lock
>> -                        || (XK_ISO_Lock <= keysym
>> -                            && keysym <= XK_ISO_Last_Group_Lock)
>> -#endif
>> -                        ))
>> +                  && !is_modifier_key)
>>                  {
>>                    STORE_KEYSYM_FOR_DEBUG (keysym);
>>                    /* make_lispy_event will convert this to a
>> symbolic
>> @@ -24204,7 +24195,11 @@ handle_one_xevent (struct x_display_info
>> *dpyinfo,
>>                    STORE_KEYSYM_FOR_DEBUG (copy_bufptr[i]);
>>                  }
>>  -             if (nbytes)
>> +              /* Mind that NBYTES can be set even if KEYSYM
>> +                 represents a modifier key, but that no character
>> +                 events should be sent in that case.  */
>> +
>> +              if (nbytes && !is_modifier_key)
>>                  {
>>                    inev.ie.kind =  MULTIBYTE_CHAR_KEYSTROKE_EVENT;
>>                    inev.ie.arg = make_unibyte_string  (copy_bufptr,
>> nbytes);

Please excuse my carelessness, I appear to have ommitted a chunk of the
diff:

diff --git a/src/xterm.c b/src/xterm.c
index 6a1642ff56e..4b2da066694 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -23734,6 +23734,7 @@ handle_one_xevent (struct x_display_info *dpyinfo,
              ptrdiff_t i;
              unsigned int old_state;
              struct xi_device_t *device, *source;
+             bool is_modifier_key;
 
              coding = Qlatin_1;
 
@@ -24091,6 +24092,18 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                      goto xi_done_keysym;
                    }
 
+                 is_modifier_key = (IsModifierKey (keysym)
+                                    /* The symbols from XK_ISO_Lock
+                                       to XK_ISO_Last_Group_Lock
+                                       don't have real modifiers but
+                                       should be treated similarly to
+                                       Mode_switch by Emacs. */
+#if defined XK_ISO_Lock && defined XK_ISO_Last_Group_Lock
+                                    || (XK_ISO_Lock <= keysym
+                                        && keysym <= XK_ISO_Last_Group_Lock)
+#endif
+                                    );
+
                  /* Random non-modifier sorts of keysyms.  */
                  if (((keysym >= XK_BackSpace && keysym <= XK_Escape)
                       || keysym == XK_Delete
@@ -24175,17 +24188,7 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                       /* Any "vendor-specific" key is ok.  */
                       || (keysym & (1 << 28))
                       || (keysym != NoSymbol && nbytes == 0))
-                     && ! (IsModifierKey (keysym)
-                           /* The symbols from XK_ISO_Lock
-                              to XK_ISO_Last_Group_Lock
-                              don't have real modifiers but
-                              should be treated similarly to
-                              Mode_switch by Emacs. */
-#if defined XK_ISO_Lock && defined XK_ISO_Last_Group_Lock
-                           || (XK_ISO_Lock <= keysym
-                               && keysym <= XK_ISO_Last_Group_Lock)
-#endif
-                           ))
+                     && !is_modifier_key)
                    {
                      STORE_KEYSYM_FOR_DEBUG (keysym);
                      /* make_lispy_event will convert this to a symbolic
@@ -24204,7 +24207,11 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                      STORE_KEYSYM_FOR_DEBUG (copy_bufptr[i]);
                    }
 
-                 if (nbytes)
+                 /* Mind that NBYTES can be set even if KEYSYM
+                    represents a modifier key, but that no character
+                    events should be sent in that case.  */
+
+                 if (nbytes && !is_modifier_key)
                    {
                      inev.ie.kind = MULTIBYTE_CHAR_KEYSTROKE_EVENT;
                      inev.ie.arg = make_unibyte_string (copy_bufptr, nbytes);