trailing whitespace almost always added by company-capf of file names in ess-r-mode

[rdiaz02]

In R code buffers (ess-r-mode), when completing filenames, almost always a trailing whitespace is added to the end of the filename, and this is undesirable. The backend being used is company-capf (see output from company-diag, below).

Interestingly, this same backend does not add the trailing whitespace on iESS buffers (note: I had to add company-capf to the backends in the iESS buffer, as it is not used by default, and without it, there is no filename completion).

I reported this in company's discussion (company-mode/company-mode#1511) and @dgutov found that by setting comint-completion-addsuffix to nil this could be avoided.

Thus

(add-hook 'ess-r-mode-hook (lambda()
				 (setq-local comint-completion-addsuffix nil)))

works. However, it would probably be a good idea to have this work out-of-the-box without requiring to modify a var via a hook?

[mmaechler]

Thank you, Ramon. I use file name completion very often in emacs and ESS, but am not using any special backend,
and it has worked fine, always (w/o any space added ..).
In that sense there is no bug in ESS, but then (as you mention), in the interaction between comint (part of Emacs) and your company-mode setup ?

[rdiaz02]

Hi Martin. Thanks for your reply. I thought it was my config, but I can reproduce this without loading my config. This is what I do

1. emacs -Q
2. M-x package-initialize
3. find-file an R file (in a directory that contains other files).
4. M-x company-mode
5. (So that it is easier to see where parenthesis and quotes start and end, M-x electric-pair-mode, though this does not change anything relevant.)
6. Type something like source("file") [assuming there are other files with name file*]
7. When I select the entry, a trailing white space is added.

Since I am using emacs -Q I do not think this is due to anything in my config.

I am using right now GNU Emacs 30.1.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.43, cairo version 1.18.2) of 2025-02-25 and ess-20250110.1437.

The following two are screenshots right after steps 6 and 7, respectively.