ZLE got wrong prompt line size, resulting redisplay eats lines when called

ZLE got wrong prompt line size, resulting redisplay eats lines when called

[Zang]

Step to reproduce:

1. Run zsh in clean mode
```
zsh -d -f -i
```

2. Set PROMPT, fill line with dash, then carriage return, fill line
with dash again
```
PROMPT="${(pl:${COLUMNS}::-:)}$terminfo[cr]\
${(pl:${COLUMNS}::-:)}$terminfo[cr]\

%# "
```

By using this PROMPT, we filled the first line of the PROMPT with
dashes twice, it takes only a single line.
But it seems that ZLE doesn't understand carriage return, it considers
that the PROMPT takes multiple lines.

3. Bind ctrl-X to redisplay
```
bindkey "^X" redisplay
```

4. By pressing ctrl-x, one will experience the bug, that PROMPT is
eating lines from previous command outputs.

Re: ZLE got wrong prompt line size, resulting redisplay eats lines when called

[Mikael Magnusson]

On 10/24/22, Zang <zealot0630@gmail.com> wrote:
> Step to reproduce:
>
> 1. Run zsh in clean mode
> ```
> zsh -d -f -i
> ```
>
> 2. Set PROMPT, fill line with dash, then carriage return, fill line
> with dash again
> ```
> PROMPT="${(pl:${COLUMNS}::-:)}$terminfo[cr]\
> ${(pl:${COLUMNS}::-:)}$terminfo[cr]\
>
> %# "
> ```
>
> By using this PROMPT, we filled the first line of the PROMPT with
> dashes twice, it takes only a single line.
> But it seems that ZLE doesn't understand carriage return, it considers
> that the PROMPT takes multiple lines.

If you're printing characters that move the cursor, it is up to you to
tell zsh about it. In this case I suppose you could surround the
entire construct with %{ %}.

-- 
Mikael Magnusson

Re: ZLE got wrong prompt line size, resulting redisplay eats lines when called

[Zang]

On Mon, Oct 24, 2022 at 4:20 PM Mikael Magnusson <mikachu@gmail.com> wrote:
> If you're printing characters that move the cursor, it is up to you to
> tell zsh about it. In this case I suppose you could surround the
> entire construct with %{ %}.
>

%{ %} works for me. I wish there can be some debug message when any
unrecognized character is encountered while calculating string size.
It is not easy to triangle the root cause of the problem while one
just experiences that some lines are mysteriously gone.

> --
> Mikael Magnusson