ESS layer help.start makes inferior ess read-only

[izahn]

Description

Starting an R repl and opening the help system in a browser makes the inferior-ess buffer read-only.

Reproduction guide

• Start Emacs
• SPC a' R <ret> to start an R repl (requires ess layer)
• At the R prompt type help.start() to launch R help in a browser
• Click on a link in the browser, e.g., "Packages".

Observed behaviour:
In the inferior ess buffer I see

> help.start()
starting httpd help server ... done
If the browser launched by '/usr/bin/xdg-open' is already running, it
    is *not* restarted, and you must switch to its window.
Otherwise, be patient ...
> 
Making 'packages.html' ... done

(which is expected), but further input is impossible. Any attempt to type in the inferior ess buffer results in Text is read-only being echoed in the minibuffer.

Expected behaviour:
The R repl should be usable after starting the help system in R.

System Info

• OS: gnu/linux
• Emacs: 24.5.1
• Spacemacs: 0.105.13
• Spacemacs branch: develop (rev. 895455d)
• Graphic display: t
• Distribution: spacemacs
• Editing style: hybrid
• Completion: ivy
• Layers:

(spacemacs-ivy auto-completion command-log emacs-lisp ess octave python sql latex git markdown org pdf-tools pandoc
               (shell :variables shell-default-height 35 shell-default-position 'bottom shell-default-shell 'multi-term)
               (mu4e :variables mu4e-headers-include-related t mu4e-headers-skip-duplicates t mu4e-headers-fields
                     '((:human-date . 12)
                       (:flags . 6)
                       (:mailing-list . 10)
                       (:from-or-to . 22)
                       (:thread-subject))))
(spacemacs-ivy auto-completion command-log emacs-lisp ess octave python sql latex git markdown org pdf-tools pandoc
               (shell :variables shell-default-height 35 shell-default-position 'bottom shell-default-shell 'multi-term)
               (mu4e :variables mu4e-headers-include-related t mu4e-headers-skip-duplicates t mu4e-headers-fields
                     '((:human-date . 12)
                       (:flags . 6)
                       (:mailing-list . 10)
                       (:from-or-to . 22)
                       (:thread-subject))))

Backtrace

No error is triggered, so no backtrace.

[izahn]

I can also reproduce this on the latest released version of spacemacs, i.e.,

System Info

• OS: gnu/linux
• Emacs: 24.5.1
• Spacemacs: 0.105.13
• Spacemacs branch: master (rev. 2c3e6b4)
• Graphic display: t
• Distribution: spacemacs
• Editing style: hybrid
• Completion: helm
• Layers:

(spacemacs-ivy auto-completion command-log emacs-lisp ess octave python sql latex git markdown org pdf-tools pandoc
               (shell :variables shell-default-height 35 shell-default-position 'bottom shell-default-shell 'multi-term)
               (mu4e :variables mu4e-headers-include-related t mu4e-headers-skip-duplicates t mu4e-headers-fields
                     '((:human-date . 12)
                       (:flags . 6)
                       (:mailing-list . 10)
                       (:from-or-to . 22)
                       (:thread-subject))))

[izahn]

OK, I've narrowed it down to an interaction with the shell layer. Without the shell layer enabled it works fine, with the shell layer enabled I have this problem. Digging in to the shell layer code now.

[izahn]

The shell layer sets comint-prompt-read-only to a non-nil value, which is enough to reproduce the problem after loading ess-site after starting with emacs -q. I've reported this upstream at emacs-ess/ESS#300 but will leave this open pending a response from the ESS developers.

[StreakyCobra]

👍 :-)

[jackkamm]

This same issue make it impossible to kill a shinyApp() running in ESS -- trying to send the kill signal with C-c C-c just results in the message Text is read-only in the minibuffer. The line (setq comint-prompt-read-only t) that @izahn identified in the shell layer causes the problem.

There is a solution in a comment on the corresponding issue page for ESS (emacs-ess/ESS#300 (comment)), to add the following toinferior-ess-mode-hook:

(setq-local comint-use-prompt-regexp nil)
(setq-local inhibit-field-text-motion nil)

I will submit this as a PR to the ess layer.

[github-actions]

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