Re: emacs-29 80e1037df44: Add string-interpolation feature to bash-ts-mode

[Kévin Le Gouguec]

Hey Yuan,

Yuan Fu <casouri@gmail.com> writes:

> branch: emacs-29
> commit 80e1037df44c0b4607423d744a8b9b409a15efce
> Author: Yuan Fu <casouri@gmail.com>
> Commit: Yuan Fu <casouri@gmail.com>
>
>     Add string-interpolation feature to bash-ts-mode
>     
>     * lisp/progmodes/sh-script.el:
>     (bash-ts-mode): Add string-interpolation feature.
>     (sh-mode--treesit-settings): Add rule for string-interpolation feature.

Prior to that commit, I rather liked how bash-ts-mode handled command
substitutions; specifically, how syntactic elements (commands, "quoted
words", ${variables}) were fontified just as well inside `backticks` or
$(parens) as outside.

(See for example some `echo $stuff | sed -e 'morestuff'` pipelines we
have in autogen.sh)

AFAICT I can get that back with something like…

  (mapc (lambda (l) (delq 'string-interpolation l))
        treesit-font-lock-feature-list)
  (treesit-font-lock-recompute-features)

… but I wonder if there might be a way to have my cake and eat it too?
E.g. theming sh-quoted-exec to something more subtle (like a faint
background), I've tried replacing :override t in the hunk below with
:override 'append, but that does not seem to be enough to get all the
syntax elements back; only "quoted words" seem to return.

I know that the current implementation more or less has feature parity
with sh-mode's bash dialect (it's actually an improvement, because it
handles $(nested $(command) substitutions) better); still, wondering if
(1) what I have in mind sounds achievable (2) there is appetite for it.

> ---
>  lisp/progmodes/sh-script.el | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/lisp/progmodes/sh-script.el b/lisp/progmodes/sh-script.el
> index 4c06efc8146..29820049636 100644
> --- a/lisp/progmodes/sh-script.el
> +++ b/lisp/progmodes/sh-script.el
> @@ -1619,7 +1619,8 @@ not written in Bash or sh."
>      (setq-local treesit-font-lock-feature-list
>                  '(( comment function)
>                    ( command declaration-command keyword string)
> -                  ( builtin-variable constant heredoc number variable)
> +                  ( builtin-variable constant heredoc number
> +                    string-interpolation variable)
>                    ( bracket delimiter misc-punctuation operator)))
>      (setq-local treesit-font-lock-settings
>                  sh-mode--treesit-settings)
> @@ -3289,6 +3290,12 @@ See `sh-mode--treesit-other-keywords' and
>     :language 'bash
>     '([(string) (raw_string)] @font-lock-string-face)
>  
> +   :feature 'string-interpolation
> +   :language 'bash
> +   :override t
> +   '((command_substitution) @sh-quoted-exec
> +     (string (expansion (variable_name) @font-lock-variable-name-face)))
> +
>     :feature 'heredoc
>     :language 'bash
>     '([(heredoc_start) (heredoc_body)] @sh-heredoc)

(Sorry for coming late to the party, I know this dates from
<83bklacluc.fsf@gnu.org>, but I wanted to find the time to tinker a bit
before badgering you)