Revert "Don't trigger a key event if a key with the same associated char was pressed (#13773)"

[erlehmann]

This reverts commit d57c936.

The reverted commit prevented recognition of key combinations.

Several keyboard layouts use a key combination to input a “+” (e.g. Neo2);
therefore some users could no longer input “+” to increase the view range.

Goal of the PR

I want to be able to input a “+” again in Minetest, outside of chat.

How does the PR work?

The PR simply reverts the logic that prevents recognition of key combinations.

Does it resolve any reported issue?

This PR resolves two issues actually:

• Restore the +/- numpad default behaviour (increase/decrease viewing range) #13890
• Key combinations are no longer recognized and can not be bound in the keybinding dialog anymore, which means inputing a “plus” is not possible without a keypad (Linux, X11/SDL, Neo 2 layout) #13899

The PR unresolves this issue:

• Don't trigger a key event if a key with the same associated char was pressed #13773

It is probably possible to fix this issue again in a way that does not cause multiple regressions.
In any case, reverting the solution for #13773 just restores what Minetest did for many years.

Does this relate to a goal in the roadmap?

• Fixing issues
• General correctness.

Default keybindings being unusable unless you have a layout where “+” can be input without using a modifier key seems incorrect to me.

How to test

1. Set your keyboard layout to German (Neo2).
2. Verify that you can not increase the viewing range by pressing ISO Level 3 Shift (the key above the left Shift key) and b together (which inputs a “+”) at the commit previous to this patch.
3. Verify that you can increase the viewing range by pressing ISO Level 3 Shift (the key above the left Shift key) and b together (which inputs a “+” ) with the patch in this PR.
4. Verify that you can increase the viewing range by pressing the “+” key on the Numpad with the patch in this PR.

[erlehmann]

Other keyboard layouts that need a key combination to input a plus sign (without a numpad, i.e. on laptops) are:

• French AZERTY (Shift =) before AZERTY amélioré
• Belgian AZERTY (Shift =)
• USA QWERT (Shift =)
• US-International (Shift =)
• UK QWERTY (Shift =)
• Polish QWERTS (Shift 6)
• Dvorak simplified (Shift =)
• Colemak (Shift =)
• MIT Space Cadet (Shift =)
• 4800-52 mainframe / dumb terminal keyboard (Shift =)
• Azerbaijani QÜERTY (Shift =)
• Dvorak-fr (Shift [)
• Bulgarian Cyrillic (Shift 3)
• Japanese QWERTY (Shift ;)

… so I am pretty sure at least some other layout than Neo 2 would be affected negatively without this patch.

Edit: IIRC Shift is bound to sneak by default in Minetest though, so I have no idea how this can work at all.

Edit 2: According to an IRC discussion, Shift works fine. Unclear how that is different from other modifiers.

[grorp]

I think it makes sense to revert #13773 for now. It seems unlikely that we will find good alternative solutions for #13890 and #13899 before the release.

After a full migration to the SDL Irrlicht device, a better solution to #13770 might be to use SDL scancodes for user-defined bindings and most default bindings, but SDL keycodes for the default "viewing range" bindings. (Assuming both the Neo2 plus combination and the numpad plus trigger the "SDLK_PLUS" SDL keycode.) (See also minetest/irrlicht#207.)

[SmallJoker]

Players can still use the the numpad by having NumLock disabled to assign the arrow keys instead.