On 2021-08-16 08:17, David Bremner <david@tethera.net> writes:

> That particular function won't work for us because it would introduce a
> new dependency on s.el. But if someone wants to make an equivalent using
> only core emacs functions and integrate it into notmuch-tag, that seems
> likely OK to me.

What is the minimal emacs version notmuch requires? Because if it’s
above 24.4, we could use string-trim-right:

string-trim-right is a compiled function defined in subr-x.el.gz.

Signature
(string-trim-right STRING &optional REGEXP)

Documentation
Trim STRING of trailing string matching REGEXP.

REGEXP defaults to  "[ \\t\\n\\r]+".

Demos
:PROPERTIES:
:added:    24.4
:changes:  26.1 The optional REGEXP argument is added.
:END:

Best,

Alan