Ctrl/Shift + function keys mappings do not work

[antoinemadec]

• nvim --version: NVIM v0.2.1-944-g77f1392
• Vim (version: 7.4.1689) behaves differently? Yes
• Operating system/version: Ubuntu 16.04
• Terminal name/version: GNOME Terminal 3.18.3 / terminator 0.98
• $TERM: xterm-256color

Steps to reproduce using nvim -u vimrc_test.txt

Minimal vimrc to reproduce the issue: vimrc_test.txt
In normal mode, press F5, then Ctrl+F5, then Shift+F5.

Actual behaviour

F5 echos "FOO"
Ctrl+F5 mapping does not work
Shift+F5 mapping does not work

Expected behaviour

F5 echos "FOO"
Ctrl+F5 echos "BAR"
Shift+F5 echos "HELLO"

It seems Ctrl/Shift + function keys mappings do not work in neovim.
I tried to bisect to the cause of regression, but it seems this issue has been present from at least v0.1.7

Cheers,
Antoine

[teto]

"xterm-256color" is not good for "GNOME Terminal 3.18.3" thought it won't solve this.

Have you tried with neovim-qt ? the problem most likely lies with the terminal though I've no solution to offer but others might.

[justinmk]

see also #5795

@antoinemadec thanks for bisecting, this is a known issue. Most likely we need to send extra info to libtermkey in tui/input.c.

[nateozem]

I found the issue. It's because there is a mismatch data between the mapped command and input buffer.

The reason <f5> works because the data from input_buffer->read_ptr matches to the value from a field called m_keys. This field came from one of the elements inside maphash.

However, when <c-f5> is pressed, there wouldn't be a match because input_buffer->read_ptr contains the data value of 0x80466a (length of 3) and the element, from maphash that suppose to be matched with, has a different value of 0x80fc04806b35 (length of 6) from m_keys field.

I don't know if this is libtermkey issue or the key mapping needs to be updated.

Please let me know which direction to take.

[nateozem]

To note:
input_buffer->read_ptr is set when input_enqueue() is called.
The function, that contains the logic for matching, is from vgetorpeek().

[nateozem]

From my last inspection, it might not be a bug, but a problem with the keyboard configuration from the terminal emulator itself.
My terminal is set in a way that the following works for me:

nmap <F17> :echo "HELLO"<CR>
nmap <F29> :echo "BAR"<CR>

Have you tried mapping to <F17> or <F29>? Any of them not work?
As mention from #5795, try executing $ showkey -a to see what the key value comes back with?

[antoinemadec]

@nateozem , here are the answers to your questions:

showkey -a:
F5
^[[15~ 27 0033 0x1b
91 0133 0x5b
49 0061 0x31
53 0065 0x35
126 0176 0x7e
Ctrl+F5
^[[15;5~ 27 0033 0x1b
91 0133 0x5b
49 0061 0x31
53 0065 0x35
59 0073 0x3b
53 0065 0x35
126 0176 0x7e
Shift+F5
^[[15;2~ 27 0033 0x1b
91 0133 0x5b
49 0061 0x31
53 0065 0x35
59 0073 0x3b
50 0062 0x32
126 0176 0x7e

map on F17 and F29:
F17 mapping catches Shift+F5
F29 mapping catches Ctrl+F5

If it is not a bug from neovim:

1. what should I change on my side ?
2. how come vim is working fine when neovim is not ?

[nateozem]

1. I'm don't know how to change the key value for gnome terminal. With iterm2, it has the ability add (or change) the keys in the preference settings. To make it work with <c-f5> & <s-f5>, I had to changed the key values as follows:
   ^F5 to send as \E[>15;5~
   and
   <Shift>F5 to send as \E[>15;2~
   If you can see, there is a small difference and that difference is by adding > character.
   You may see the values I used is from xterm+pcf3.
2. My guess for the reason why vim works, they are probably transforming the value that comes from pressing the function + modifier keys into one kind of value. Or they probably mapped the keys like so :nmap <f29> <c-f5>.

It's a good question and I'll try to confirm this.

[antoinemadec]

@nateozem thanks for your response and support. However what you propose sounds like a workaround. I was more expecting to have to change $TERM or something like that.

Here are my questions:

1. To be clear, do you mean that gnome terminal, terminator (my every day terminal) and iterm2 don't handle <c-func_keys> & <s-func_keys> properly ?
2. If so, do you know a terminal that handles it properly ?

I know very little about key values and how they are generated but those are very mainstream terminals. Besides, the fact that Vim works fine makes me even more skeptical when you say that the issue does not come from Neovim.
But once again, I know very little about those things.

Cheers!

[nateozem]

I was going to write something elegant, but I'll try to answer as best as I can.

iterm2 and gnome-terminal are working properly. neovim is also working properly. There is just a misunderstanding of the expectation of what the keycodes suppose to be within terminal emulator (that includes me).

I have tested vim and my assumption is correct. vim wouldn't work if I change the keycodes to the values I have mentioned. I tried changing gnome-terminal keycodes for testing, but there aren't no easy way (maybe none at all). So I tested "Konsole" application instead and able to change the keycodes. Then, I tested neovim under the same condition and tested vim to verify my assumption.

To conclude, I don't know if "proper" is the right way of looking at this issue. I'd suggest the focus to be on "simplicity" and "clearness". I would agree, from my finding, it's not the case. To answer the last question, I don't know if there are any terminal emulator that handles it properly.

Sorry I don't have a definitive answer. I'd think someone more knowledgeable than me would weigh in.