bug#5414: 23.1.91; /sys/devices files trigger loading tramp

[Michael Albinus <michael.albinus@gmx.de>]

Chong Yidong <cyd@stupidchicken.com> writes:

> Here's a proper recipe for reproducing this (the previous recipe does
> not do it, maybe it was untested):
>
>  emacs -Q
>  C-x C-f
>  C-a C-k
>  /sys/devices/pc [TAB]
>     => Tramp will be loaded

Thanks, I can reproduce it as well.

Tramp is loaded due to `rfn-eshadow-update-overlay'. In the loop
commented with "Binary search ...", it recomputes `mid', and calls
`rfn-eshadow-sifn-equal'. This function applies
`substitute-in-file-name' for a part of the the whole file name, which
looks like a remote file name, accidently. Bingo!

See the backtrace:

  tramp-file-name-handler(substitute-in-file-name "/pci0000:00/")
  substitute-in-file-name("/pci0000:00/")
  byte-code("ÁÂ\bd\"!‡" [pos substitute-in-file-name buffer-substring-no-properties] 4)
  byte-code("ÆÇ !È\b!É d\x19\x1a^[\x1c\vƒ;\0\v	=„'\0\f\vT\x1d‰\x1cÊË̏š*„;\0\v
=„‡\0\f\v\x1d‰\x1cÊË̏š*„‡\0
T	W„a\0	TdWƒ€\0\f	T\x1d‰\x1cÊË̏š*ƒ€\0	T\x12d‰\x11ƒ€\0
	\\Í¥\x13\f\v\x1d‰\x1cÊË̏š*ƒ{\0\v‰\x12‚<\0\v\x11‚;\0Î\bÉ 
#ˆÏÐ!,‡" [rfn-eshadow-overlay end start mid goal pos substitute-in-file-name minibuffer-contents overlay-end minibuffer-prompt-end nil (byte-code "ÁÂ\bd\"!‡" [pos substitute-in-file-name buffer-substring-no-properties] 4) ((error)) 2 move-overlay run-hooks rfn-eshadow-update-overlay-hook] 5)
  rfn-eshadow-update-overlay()
  run-hooks(post-command-hook)

I wouldn't regard it as a bug. One could argue, that rfn-shadow should
deactivate file name handlers for its work, but this might result in
collateral damages.

Best regards, Michael.