> On 26 Jul 2019, at 13:30, Viktor Mitin <viktor.mitin...@gmail.com> wrote: > > Hi All, > > The Xen Project has a coding standard in place, but like many > projects, the standard is only enforced through peer review. Such > mistakes slip through and code is imported from other projects which > may not follow the same standard. The goal would be to come up with a > tool that can audit the code base as part of a CI loop for code style > inconsistencies and potentially provide corrections. This tool is to > embed as a part of the continuous integration loop. For clarity, let’s > call such a tool as ‘Xen checkpatch tool’. > > References for those who are interested in the background are in [5]. > > The idea of the new tool is to use the clang-format approach as a base > for Xen ‘checkpatch’ process. The new tool consists of modified > clang-format binary and modified clang-format-diff.py python script to > automate Xen patches format checking and reformatting. The tool can be > used as a pre-commit hook to check and format every patch > automatically. See the tool code under [1]. > > Known limitations: > > Xen coding style > Xen coding style is defined in two 'CODING_STYLE' documents in Xen > code: Xen common coding style and Xen libxl coding style. The > documents describe some of the coding style rules. However, there is > no information about ‘base’ coding style used (i.e. K&R, Linux, LLVM, > Google, Chromium, Mozilla, WebKit…). For this reason, it is unclear > how to deal with some of the coding style rules not described in the > Xen coding style documents. See examples of the tool output under [2]. > > Clang-format > Generally, the design of clang-format is to only make formatting > changes, not adding or removing tokens (there are some exceptions to > this, like wrapping string literals). It means that clang-format can't > add or remove braces or change the style of the comments from C89 to > C++. Tool clang-tidy can make syntactic changes to the code. However, > unfortunately, clang-tidy is a heavyweight tool as it needs the > compile options to parse the file (See [3] and [4]) > > This can be clang generic limitation, e.g. we might want to add a > possibility to clang to alter the code, e.g. adding braces, > characters, etc". The concern here is that it seems it is against main > clang-format design principles, so those changes will not be > integrated into clang-format mainstream. It should be checked with > clang-format community first. > > As an option, to overcome the limitations of clang-format tool in the > case of Xen coding style, it is possible to move some Xen code format > logic to the modified clang-format-diff.py tool. > > Summary > To sum up, it is possible to automate Xen patches format checking and > corrections with some known clang-format limitations. Ideally, it > would be good to slowly migrate the entire code-base to be conforming, > thus eliminating the need for discussing and enforcing style issues > manually on the mailing list. The ‘Xen checkpatch tool’ provides the > closest approximation of the established Xen style (including styles > not formally spelled out by CODING_STYLE, but commonly requested). > The tool can be used as-is at the moment and improved later in case of > necessity. > > The tool allows achieving automation of Xen patches format checking > and corrections with some known clang-format limitations (see below). > All the xen/*.c files have been tested with it. > See the results of the tool output under [2]. > > Summary of the changes: > - Added 3 new formatting styles to cover all the cases mentioned in > Xen coding style document: Xen, Libxl, Linux; > - Added list of the files and corresponding style name mappings; > - Added indentation according to Xen coding style; > - Added white space formatting according to Xen coding style; > - Added bracing support exception for do/while loops; > > Added to clang-format, however, probably this logic should be moved to > python part (see known clang-format limitations above): > - Braces should be omitted for blocks with a single statement. Note: > these braces will be required by MISRA, for example, so it is probably > worth adding such a requirement to the coding style. > - Comments format requirements. Note: //-style comments are defined in > C99 as well, and not just in the case of C++. C99 standard is 20-years > old… > > To be added: > - Emacs local variables. Open points: Why to keep emacs local > variables in Xen code? What about other editors' comments (vim)? > - Warning to stderr in the case when ‘unfixable’ line/s detected. > > To be fixed: > - Max line length from 80 to 79 chars; > - Disable // comments; > > > The links: > [1] > https://github.com/xen-troops/Xen-Clang-format/blob/devel/clang-format.patch > [2] > https://raw.githubusercontent.com/viktor-mitin/xen-clang-format-example/master/0001-clang-format-checkpatch-output-example.patch > [3] https://developer.blender.org/T53211 > [4] > http://clang-developers.42468.n3.nabble.com/clang-format-add-around-statement-after-if-while-for-td4049620.html > > [5] > Project status: > https://docs.google.com/document/d/10NJn-QvO1TvyJJJGE2PD6FtElYCT3neBAffIqeWHdiE/edit > > <https://docs.google.com/document/d/10NJn-QvO1TvyJJJGE2PD6FtElYCT3neBAffIqeWHdiE/edit> This seems to be an old outreachy document
> https://docs.google.com/document/d/1tCcwZ9K38ToLGTPHZkfs2sS4s4YulrGoH8LIHwBMbg4/edit > > <https://docs.google.com/document/d/1tCcwZ9K38ToLGTPHZkfs2sS4s4YulrGoH8LIHwBMbg4/edit> I suppose this is the project status? > Mailing list discussions: > https://lists.xenproject.org/archives/html/xen-devel/2016-09/msg02848.html > https://lists.xenproject.org/archives/html/xen-devel/2017-04/msg00131.html > https://lists.xenproject.org/archives/html/xen-devel/2017-04/msg01739.html > > Original implementation on GitHub: > https://github.com/sam5125/Xen-Clang-format > <https://github.com/sam5125/Xen-Clang-format> Hi Viktor, thank you for putting this mail together and driving this forward. I added committers@ as well as Doug. I am going to let others respond first. I am assuming we are looking for some testing? Is there a simple set of instructions to get started and test the tool? Regards Lars
_______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
