Bug 18757 - Refine and test .editorconfig to set R Core style

[hturner]

A recurring annoyance for both contributors and R Core developers is that whitespace and other style changes can be introduced as a result of the contributor's IDE settings. An EditorConfig file is intended to address this exact issue.

@krlmlr shared a draft .editorconfig file in Bug 18757.

I think a useful contribution would be to refine the .editorconfig and test it with Editorconfig-Checker to identify any conflicts between the configuration and the R sources. This may help to refine the .editorconfig further and assess the impact of any unresolvable conflicts.

Here is an updated version of @krlmlr' .editorconfig:

# EditorConfig: https://EditorConfig.org

# Don't search for .editorconfig files in parent directories (may conflict)
root = true

# Global settings:
[*]
# Unix-style newlines with a newline ending every file
end_of_line = lf
insert_final_newline = true
# Set default charset
charset = utf-8
# In an ideal world, the setting below would be true, but we want to remove the existing
# spaces at EOL first before turning that on.
trim_trailing_whitespace = false

# DESCRIPTION is special, don't remove trailing spaces after :
[DESCRIPTION]
trim_trailing_whitespace = false

# C files: indentation = 4 spaces; every 8 spaces in indentation replaced with tab
[*.c]
indent_style = tab
indent_size = 4
tab_width = 8

# R files: indentation = 4 spaces (always); any tab should be displayed as 8 spaces
[*.R]
indent_style = space
indent_size = 4
tab_width = 8

# Rd files: indentation = 2 spaces (always)
[*.Rd]
indent_style = space
indent_size = 2

# Makefiles: Tab indentation (no size specified)
[Makefile]
indent_style = tab

The indentation rules for R and C files are consistent with @mmaechler's Comment 1 in the bug report. I have tested this with Vim and Emacs. Unfortunately the C configuration doesn't work in VS Code or Positron, as VS Code can not be set to replace spaces with tabs (see microsoft/vscode#42740, microsoft/vscode#5394). In that case, the best we can do is to use VS Code settings directly to get a close as possible to the right configuration - I'll open another issue about that.

Extension task

An extension to this task would be to add a section to the R Dev Guide, sharing the .editorconfig and how to use it Vim and Emacs. It could go in a new chapter "IDE Setup".

While there is no .editorconfig in the R sources, it is best to put it in a directory one level out from the source repository. E.g. you might have, e.g. svn/.editorconfig, then check out to svn/R-devel or similar.

Emacs

I did not need to install anything, just add (editorconfig-mode 1) to my init.el.

Vim

Install the EditorConfig plugin as a Vim8 plugin: https://github.com/editorconfig/editorconfig-vim#install-as-vim8-plugin (although I have Vim 9.1 on my mac, the EditorConfig plugin wasn't bundled in, you can check via :scriptnames).

[eddelbuettel]

While there is no .editorconfig in the R sources

Maybe we could make a case for including it, especially given the benefits to standardization you do outline quite nicely above? (Edit: Or not, see #105. That's why we can't have nice things.)

Alternatively, a common fallback is in the top-level as a local file plus an entry in ~/.gitignore (for git) and svn propset svn:ignore .editorconfig (for svn).

[MichaelChirico]

can #35 be closed as a duplicate?

[hturner]

It's not quite the same - #35 is a proposal to add an .editorconfig to R, while this is a proposal to develop and test it some more outside R to start with. But in terms of what we would do at a Dev Day, this issue probably covers it, so it does make sense to close #35.

[mmaechler]

I still favor such an eventual addition to the R sources. Indeed, it is important that it is tested in quite a few typical user setups, however, this is indeed, what 'R Dev Day' and other out-of-R-core contributors can help with. Hence "thumbs up!"

[lionel-]

Relevant issue for the Zed IDE, which doesn't support the mixed indentation style at all (not even partial support like in VS Code): zed-industries/zed#24108