Subject: 25.2; xclip fails to set X selection when using tramp

From: Ian Mackinnon <[email-masked]>
Date: Thu, 15 Nov 2018 10:41:28 +0100

When visiting a file with tramp and killing text with xclip-mode
enabled, the text gets sent to the kill-ring but the X clipboard does
not get set. Additionally, the xclip shell process does not close.

Steps to reproduce:

-   Ensure xclip is installed (In the shell: `which xclip`)
-   Install xclip Emacs package
-   Set variables `x-select-enable-clipboard` and/or
`x-select-enable-primary` to `t`.
-   Enable xclip (`M-x xclip-mode RET`)
-   Visit a file using tramp (eg. `/sudo:user@localhost:/tmp/tramp-file`)
-   Type some text
-   Select a region and kill it

Expected behaviour

-   Selected text gets sent to the kill-ring and X clipboard or primary
    buffer (this can be verified in the shell with `xclip -o -selection
primary` and/or
    `xclip -o -selection clipboard`.
-   xclip processes exit cleanly

Observed behaviour

-   Selected text gets sent to the kill-ring, but not the X clipboard or
    primary buffers.
-   xclip processes do not terminate (user is warned that they are still
    running when exiting Emacs).
-   Further, yanking text at this point causes the contents of the X
    clipboard or primary buffer to be inserted at the tip of the
    kill-ring so that gets yanked instead of the killed text.

Workarounds

As suggested in Emacs StackExchange by user Stefan
(https://emacs.stackexchange.com/q/45991/7189) replacing
`start-file-process` with `start-process` in a copy of the xclip 1.4
source fixes this particular issue though whether this causes any
unwanted side effects has not been extensively tested.

--

In GNU Emacs 25.2.2 (x86_64-pc-linux-gnu, GTK+ Version 3.23.2)
 of 2018-08-27, modified by Debian built on lgw01-amd64-037
System Description: Ubuntu 18.10

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