bug#72561: 31.0.50; Scan error in ert--pp-with-indentation-and-newline

[Eli Zaretskii <eliz@gnu.org>]

> From: "J.P." <jp@neverwas.me>
> Date: Sat, 10 Aug 2024 06:48:11 -0700
> 
> Tags: patch
> 
> This apparently began after
> 
>   2f181d60323bd9e0196775828de633100479f4c2
>   Author:     Stefan Monnier <monnier@iro.umontreal.ca>
>   AuthorDate: Fri Jun 16 13:35:06 2023 -0400
>   CommitDate: Sat Jun 17 17:24:38 2023 -0400
> 
>   pp.el (pp-fill): New default pp function
>   
>   1 file changed, 90 insertions(+), 1 deletion(-)
>   lisp/emacs-lisp/pp.el | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++-
> 
> So I guess it also affects Emacs 30. To reproduce, put this in
> test/lisp/emacs-lisp/ert-tests.el:
> 
>    (ert-deftest ert--pp-with-indentation-and-newline ()
>      (should (equal '((:one "1" :three "3" :two "2")) '((:one "1")))))
> 
> Then run something like:
> 
>    $ make -C test \
>      SELECTOR=ert--pp-with-indentation-and-newline \
>      lisp/emacs-lisp/ert-tests.log
> 
>    Error: scan-error ("Containing expression ends prematurely" 221 221)
>      forward-sexp-default-function(-1)
>      forward-sexp(-1)
>      calculate-lisp-indent((5 221 238 nil nil nil 4 nil nil (5 27 161 175
>      lisp-indent-calc-next(#s(lisp-indent-state :stack (50 16 6 5 nil) :p
>      indent-sexp()
>      ert--pp-with-indentation-and-newline((ert-test-failed ((should (equa
>      #f(compiled-function (event-type &rest event-args) #<bytecode 0x16b6
>      #f(compiled-function () #<bytecode -0xb4ce749a56118cd>)()
>      ert-run-or-rerun-test(#s(ert--stats :selector ert--pp-with-indentati
>    
>    Aborted: Ran 1 tests, 0 results as expected, 1 unexpected, -1 skipped
>    
> No idea if there's a deeper issue at play here, maybe something in
> pp.el that a patch like the attached would just be papering over.

Adding Stefan.