[cfe-dev] clang-format custom format specification

[David Blaikie via cfe-dev]

I've cc'd Sam McCall who might have opinions on the specific feature
you're suggesting. In the mean time I'd like to/be happy to drill down
a bit more into your use case, perhaps there are other solutions or
it'll give Sam more context when he can reply

On Tue, Sep 15, 2020 at 10:21 AM Kyle Knoepfel <kyleknoepfel at gmail.com> wrote:
>
> David, the current situation I'm faced with is that we're experimenting with different formats, and there is no .clang-format file that resides in the directory hierarchy.

What sort of experiments are you running? If it's a matter of using
different formats in different parts of the codebase, that could be
done with more narrowly scoped .clang-format files, for instance. If
the project isn't open to having any .clang-format files checked in
during the experimentation phase, that's trickier - could put one
up/above/outside the project - but couldn't do that and have different
sub directories running different experimental formats.

> Once we settle on a format, I expect the .clang-format to be included in the source-code repository, and this problem can be a non-issue.  Until we get there, however, this would be a very helpful safety mechanism.
>
> That said, I'm very cognizant of the XY problem, and do not want to be a perpetrator of it.
>
> Thanks for your response,
> Kyle
>
> > On Sep 15, 2020, at 3:14 AM, David Blaikie <dblaikie at gmail.com> wrote:
> >
> > "clang-format for each input file will try to find the .clang-format
> > file located in the closest parent directory of the input file." - so
> > it shouldn't matter which directory you invoke the command from. If
> > you have the .clang-format file in the parent of the file you want to
> > format, it should always get that format.
> >
> > Perhaps there's something broken in your setup that's causing that
> > behavior not to work?
> >
> > On Mon, Sep 14, 2020 at 5:47 PM Kyle Knoepfel via cfe-dev
> > <cfe-dev at lists.llvm.org> wrote:
> >>
> >> Forgive me if this has already been discussed.
> >>
> >> I work on projects with different formatting guidelines.  For simple cases, it is simple to embed the .clang-format file in the correct (parent) directory, run `clang-format -style=file ...` and everyone's happy.  However, it is easy to get into a situation where the wrong format is applied, especially if you accidentally invoke the command from the wrong directory.
> >>
> >> Would Clang be opposed to a command line invocation such as:
> >>
> >> clang-format -style=custom:my-projects-format ...
> >>
> >> where a field in the .clang-format file would have the value 'my-projects-format', thus attributing the file to the format name?  If a user specified something like -style=custom:my-unsupported-format, and such a format name could not be discovered in the .clang-format file, then it would be a hard failure, not letting a silent error slip by.
> >>
> >> Thanks for your input.  If it is favorable, then I'm happy to explore implementing it.
> >>
> >> Kyle Knoepfel
> >>
> >> Software framework group leader, Fermilab
> >>
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>