Emacs on Android - org-mode - error - `(wrong-type-argument stringp (require . t-mouse))`

Question

I'm running Emacs in Android under ZShaolin, with whatever the default configuration is. When I open an org-mode file (or try to enable org-mode), I get an error:

(wrong-type-argument stringp (require . t-mouse))

[This seems to be the case whether or not I enable the trackpad (I'm running on a tablet with keyboard)]

Here is the backtrace:

Debugger entered--Lisp error: (wrong-type-argument stringp (require . t-mouse))
  string-match("\\(\\`\\|/\\)org-exp\\(\\.elc\\|\\.el\\)?\\(\\.gz\\)?\\'" (require . t-mouse))
  load-history-filename-element("\\(\\`\\|/\\)org-exp\\(\\.elc\\|\\.el\\)?\\(\\.gz\\)?\\'")
  eval-after-load("org-exp" (add-hook (quote org-export-preprocess-before-normalizing-links-hook) (quote org-remove-file-link-modifiers)))
  org-mode()
  set-auto-mode-0(org-mode nil)
  set-auto-mode()
  normal-mode(t)
  after-find-file(nil t)
  find-file-noselect-1(#<buffer Notes.org> "/sdcard/Android/data/com.dropbox.android/files/u139630781/scratch/Org/Notes.org" nil nil "/storage/emulated/legacy/Android/data/com.dropbox.android/files/u139630781/scratch/Org/Notes.org" ((16419 . 51200) 20))
  find-file-noselect("/sdcard/Android/data/com.dropbox.android/files/u139630781/scratch/Org/Notes.org" nil nil t)
  find-file("/sdcard/Android/data/com.dropbox.android/files/u139630781/scratch/Org/Notes.org" t)
  call-interactively(find-file nil nil)

Answer 1

Seems like your Emacs has a malformed load-history variable. Its documentation states:

Documentation: Alist mapping loaded file names to symbols and features. Each alist element should be a list (FILE-NAME ENTRIES...), where FILE-NAME is the name of a file that has been loaded into Emacs. The file name is absolute and true (i.e. it doesn't contain symlinks). As an exception, one of the alist elements may have FILE-NAME nil, for symbols and features not associated with any file.

In your case load-history contains an element whose car is not a string but (require . t-mouse). load-history-filename-element expects a file name (a string) and bails.

I don't know what the reason is (and cannot find out because I don't have an Android device) , but we can try to get around this by creating a slightly more robust version of load-history-filename-element:

(defun load-history-filename-element (file-regexp)
  "Get the first elt of `load-history' whose car matches FILE-REGEXP.
        Return nil if there isn't one."
  (let* ((loads load-history)
         (load-elt (and loads (car loads))))
    (save-match-data
      (while (and loads
                  (or (null (car load-elt))
                      (not (and (stringp (car load-elt)) ; new condition
                                (string-match file-regexp (car load-elt))))))
        (setq loads (cdr loads)
              load-elt (and loads (car loads)))))
    load-elt))

For the record, this is the original version (Emacs 24.4.1):

(defun load-history-filename-element (file-regexp)
  "Get the first elt of `load-history' whose car matches FILE-REGEXP.
    Return nil if there isn't one."
  (let* ((loads load-history)
         (load-elt (and loads (car loads))))
    (save-match-data
      (while (and loads
                  (or (null (car load-elt))
                      (not (string-match file-regexp (car load-elt)))))
        (setq loads (cdr loads)
              load-elt (and loads (car loads)))))
    load-elt))

All of this is a bit of a shot in the dark, but I hope it helps.

Answer 2

For the record: I have dug up the root cause for this one. It is not for ZShaolin build, but rather, for Termux build of Emacs, but the source of the broken load-history entry is the same, it's an Emacs bug resulting from running undumped, which Android builds necessarily have to do.

See https://github.com/termux/termux-packages/issues/423 for the full story.

The most general solution appears to be commenting out the line (setq current-load-list nil) in /usr/share/emacs/<version>/loadup.el -- the presence of this line is intended to excise loadup.el from load-history with emacs that is dumped into a single binary with the lisp components during compilation. On Android, with the requirement that executables must be PIE, a dumped binary will simply not run, so both the ZShaolin and Termux builds of emacs run undumped, and this line results in the creation of a bogus load-history entry.