Emacs 30 breaks agda mode

[kutsurak]

A relatively recent change in pp.el in the development branch of emacs breaks the function agda2-send-command by adding newlines at the end of filenames.

To reproduce open any agda file in a recent emacs 30 build running version 2.6.4 or master (the issue is reproducible in both), and call agda2-load. This results in the following errors in the *agda2* buffer:

IOTCM "/tmp/hello-world-dep.agda"
 NonInteractive Indirect ( Cmd_load "/tmp/hello-world-dep.agda"
 [] )
Agda2> cannot read: IOTCM "/tmp/hello-world-dep.agda"
Agda2> cannot read:  NonInteractive Indirect ( Cmd_load "/tmp/hello-world-dep.agda"
Agda2> cannot read:  [] )

I used the following as a minimal emacs configuration after installing agda using stack:

;;; -*- lexical-binding: t -*-

(load-file (let ((coding-system-for-read 'utf-8))
             (shell-command-to-string "agda-mode locate")))

;; auto-load agda-mode for .agda and .lagda.md
(setq auto-mode-alist
   (append
     '(("\\.agda\\'" . agda2-mode)
       ("\\.lagda.md\\'" . agda2-mode))
     auto-mode-alist))

I am not entirely convinced that the change in the behavior of pp-to-string is correct, but I have a simple workaround until the issue has been investigated/resolved on the emacs side. A PR with it follows.

[andreasabel]

A relatively recent change in pp.el in the development branch of emacs breaks the function agda2-send-command by adding newlines at the end of filenames.

Oh, but this is also an explanation for the malformed strings in #6983 (comment) which have additional line-breaks after filenames.

So this issue is not fully fixed with

• Remove whitespace around substrings before concatenation #6954

More string-trimming is needed after we invoke pp- functions.