bug#62265: Underline does not work in Terminal Emacs

[Mohsin Kaleem]

Eli Zaretskii <eliz@gnu.org> writes:

> However, what about the non-TERMINFO branch?  Do termcap databases
> support this capability and tigetstr?  I wonder whether we should do
> one of the following:
>
>   . support "smxx" only when TERMINFO is defined
>   . support "smxx" regardless of whether TERMINFO is defined

The latter wouldn't be possible for those using terminfo because of the
issue I described before. I'm okay with the former approach but I
imagine the author of the original TTY strikethrough patch was building
Emacs without terminfo and they described the patch as working for them
so I'd have to conclude termcap does support this (in a non-compliant
ncurses way). Switching to the former approach might break their
workflow since if they build without terminfo they'd lose strikethrough
altogether. I'm happy to test whether this would be the case but not
sure how to. The difference between termcap and terminfo seem kinda
arbitrary to me and I can't find any documentation describing the exact
difference (except this sort of 2 letter restriction in termcap
extensions).

-- 
Mohsin Kaleem