[ was: Re: [pushed] [gdb/tui] Fix TUI resizing for TERM=ansi ]

On 4/30/23 21:15, Tom Tromey wrote:
>>>>>> "Tom" == Tom de Vries via Gdb-patches <gdb-patches@sourceware.org> writes:
> 
> Tom> As it happens, when TERM is set to ansi, readline decides that the terminal
> Tom> cannot auto-wrap lines, and reserves one column to deal with that, and as a
> Tom> result reports back one less than the actual screen width:
> ...
> Tom> This is currently not causing trouble in testing because we have a workaround
> Tom> in place in proc Term::resize.  If we disable the workaround:
> 
> Thank you for tracking this down.
> I never even considered this might be a readline issue.
> 
> Tom> +      readline_hidden_cols = _rl_term_autowrap ? 0 : 1;
> 
> I hate to have a new dependency on a readline internal variable.

Agreed, it's ugly.

> Don't some distros mark these as hidden in libreadline.so?
> I feel like there was another bug along these lines.
> 

That's probably PR10723 - "Dependency on readline internal variable" ( 
https://sourceware.org/bugzilla/show_bug.cgi?id=10723 ).

> However, I don't see another way to do it.

I had an earlier version of the patch that used the COLUMNS env variable 
instead.  It felt a bit hacky, so I went for _rl_term_autowrap, but 
patch attached below goes back to the COLUMNS approach.  WDYT?

> Maybe some official API could be added by the upstream readline.
> Would you want to bring it up there?
> 

If we commit the patch below, then this is solved for _rl_term_autowrap, 
but not for the other instances.

I expect bringing it up will will need to be done per instance, with a 
detailed explanation of why we need it, so that sounds like project I 
don't have time for atm.

> Anyway it seems ok to me.

Thanks for the review.

- Tom