Initial prompt invisible (regression in 5.4.1)

Initial prompt invisible (regression in 5.4.1)

[Ruud van Asseldonk]

Hi,

After upgrading from Zsh 5.3.1 to 5.4.1, the initial prompt is sometimes
not painted when I open a gnome-terminal window. See screenshot here:

https://imgur.com/a/vBDyL

There is a single text-colored pixel in the terminal at the normal
location of the cursor.

When trying to take a screenshot of this, I noticed that the prompt is
painted when the window loses (or gains, I am not sure any more) focus,
if it was not painted initally.

This does not happen consistently, it happens about 1 in 4 times when I
open a new terminal. It seems a weird issue to be a Zsh bug, but after
downgrading to 5.3.1 I have not observed this issue again. When
upgrading to 5.4.2 later I did observe the issue again.

Last known good version (of Arch package): zsh-5.3.1-2
Known bad versions: zsh-5.4.1-1, zsh-5.4.2-1

My zshrc is here:

https://raw.githubusercontent.com/ruuda/dotfiles/master/zsh/.zshrc

I did customize the prompt near the end.

Let me know if there is anything I can do to help diagnose this issue.

Kind regards,

Ruud

Re: Initial prompt invisible (regression in 5.4.1)

[Bart Schaefer]

On Sep 2, 10:22pm, Ruud van Asseldonk wrote:
}
} There is a single text-colored pixel in the terminal at the normal
} location of the cursor.

That would not be a zsh thing, the shell would never print anything
smaller than a period (.) unless you are using special drawing chars
in your prompt.

} This does not happen consistently, it happens about 1 in 4 times when I
} open a new terminal.

This sounds like a race condition.

} It seems a weird issue to be a Zsh bug, but after
} downgrading to 5.3.1 I have not observed this issue again. When
} upgrading to 5.4.2 later I did observe the issue again.

I've reviewed code changes made between those version and there has been
no update to the prompt code that would account for this.

However, there have been several changes intended to make the shell
start up faster, including a signal handling optimization around the
reading of the .zshrc et al. files.  A possibility is that the shell
now finishes its start-up and outputs the initial prompt, before the
terminal has been fully drawn by the windowing system.

As an experiment, try placing a "sleep 1" at the end of your .zshrc,
and see if that reduces the frequency of this recurring.