[systemd-devel] clang-format: auto-formatting the code base of systemd

[Sebastian Jennen]

Hello systemd team,

there is a pull request currently on systemd, which adds a .clang-format 
support, which you can find here:
https://github.com/systemd/systemd/pull/11308

clang-format is an automatic formatter for C code maintained by the llvm 
project. It works by tokenizing the source code and reassembling it 
under consideration of a single source code style defining file 
(.clang-format).

I would like to ask you to participate on a poll on this, as this topic 
is controversial.
One the hand this:
- enables programmers to auto-format their patches to comply with the 
systemd style
- fixes a couple of minor code inconsistencies
on the other hand this:
- reformats all existing code, which requires review
- break some systemd specific styles which would need be changed some 
way (see especially the formatting of table blocks in pull request)
- may annoy some developers, as custom styling is lost

Please also take into consideration the suggested file 
tools/format-file.py to extend the clang-format formatting.


Here are poll alternatives in detail, to the question, whether the new 
style should be applied:

no
--> speaks for itself

no,
--> but *some* features should be derived from it and applied to the 
code base.
That would be tedious and not automatable for future changes. This will 
not enable programmers to auto apply the code format to their patches, 
as this format would need to be cherry picked for the reformatting 
allowed by systemd.

yes
--> but with the wrapper script in tools/format-file.py as mentioned in 
the pr to be as close as possible to the existing style
Together with this script the coding style already comes quite close to 
the style in systemd right now.
All custom changes in tools/format-file.py have been posted on the llvm 
mailing list, so these changes might be implemented upstream so the 
custom script might eventually get redundant with a newer version of 
clang-format. see request on mailing list here:
http://lists.llvm.org/pipermail/cfe-dev/2019-January/060690.html

yes
--> clang-format should applied in the pure form defined by the 
.clang-format file without any wrapper script. This makes the most 
changes to the code base, but also makes it most obvious how to 
auto-format the code.

Independently source code style file and the wrapper script can further 
be changed.

You can find the poll here:
http://www.easypolls.net/poll.html?p=5c2f3659e4b026f889160411

Cheers, Sebastian Jennen