Motivation
Developers are supposed to follow Coding style. However, from time to time a PR is created and then its author is asked to change tabs to spaces, for example.
Introducing an .editorconfig file can mitigate these formatting issues.
User story
A contributor wants to create a new PR. She clones Bitcoin Core repo, opens her editor, the editor loads .editorconfig rules and writes her patch with correct formatting rules. Less Coding Style issues is then discovered in the PR review process and thus less CI runs are needed.
What is EditorConfig file?
https://editorconfig.org provides very well and concise explanation:
What is EditorConfig?
EditorConfig helps maintain consistent coding styles for multiple developers working on the same project across various editors and IDEs. The EditorConfig project consists of a file format for defining coding styles and a collection of text editor plugins that enable editors to read the file format and adhere to defined styles. EditorConfig files are easily readable and they work nicely with version control systems.
Support
.editorconfig is supported by many IDEs and text editors. Sometimes, the support is out of the box and sometimes a plugin is needed. However, for example, VS Code detects .editorconfig presence and automatically offers you to install the missing plugin.
See https://editorconfig.org/#pre-installed for details on support. To name a few:
- Visual Studio (out of the box)
- VS Code (plugin)
- JetBrains IDEs (IntelliJ IDEA, PyCharm, etc.) (out of the box)
- Sublime Text (plugin)
- Emacs (plugin)
- Vim (plugin)
Not supported (AFAIK):
My editor does not support .editorconfig
Then nothing really changes for you.
.editorconfig vs .clang-format
As explained here:
Note that Visual Studio also supports EditorConfig, which works in a similar way. ClangFormat, however, has a much larger variety of style options than EditorConfig, including some very C++ specific rules that can be set, and it is already used by C++ developers today.
Having both .editorconfig and .clang-format in a project, may not always work correctly though, I think. As some editors may have a plugin for .editorconfig and a plugin for clang-formatter which may not work correctly in unison. In VS Code & Visual Studio EditorConfig takes precedence over other settings.
Possible issues
Your editor may change formatting for some 3rd party library if you edit the code. A solution for this would be to make EditorConfig rules more specific (include only certain paths). I’m not sure if it is an issue in practice.
Testing
Add some trailing whitespace to a Python file and save the file. You should see that the trailing whitespace is removed.
Possible future work
It would be great to define rules for Makefiles. This would be good start:
0# Makefiles
1[Makefile,*.am]
2indent_style = tab
3trim_trailing_whitespace = true
I don’t know makefiles in this project good enough to propose something reasonable. If this PR is well received, it would be great to add it in this PR.
Also, there are actually many different file extensions and so the proposed .editorconfig file can be probably improved very much:
0Get-ChildItem -Recurse | % {$_.Extension.ToLower()} | sort | unique
0.1
1.ac
2.adoc
3.am
4.bash-completion
5.bat
6.bmp
7.c
8.cc
9.cert
10.cfg
11.clang_complete
12.clang-format
13.cmake
14.cmd
15.cnf
16.com
17.conf
18.cpp
19.css
20.csv
21.doxyfile
22.dtd
23.empty
24.exe
25.exp
26.gci
27.gitattributes
28.github
29.gitignore
30.gitmodules
31.guess
32.h
33.hex
34.hpp
35.html
36.icns
37.ico
38.idb
39.ilk
40.in
41.include
42.ini
43.init
44.ipp
45.jam
46.js
47.json
48.lastbuildstate
49.lib
50.list
51.log
52.m
53.m4
54.md
55.mk
56.mm
57.moc
58.obj
59.openrc
60.openrcconf
61.patch
62.pc
63.pdb
64.pl
65.plist
66.png
67.po
68.pro
69.py
70.python-version
71.qbk
72.qm
73.qml
74.qrc
75.raw
76.rb
77.rc
78.recipe
79.res
80.s
81.sage
82.sass
83.scm
84.scss
85.service
86.sgml
87.sh
88.sln
89.spec
90.sub
91.supp
92.svg
93.targets
94.td
95.tlog
96.ts
97.tx
98.txt
99.ui
100.user
101.v2
102.vcxproj
103.verbatim
104.vscode
105.xml
106.xpm
107.xsl
108.y
109.yapf
110.yml
111.yy
Fixes #21092
