Re: FORMAT_PATCH_NAME_MAX increase

[Laszlo Ersek <lersek@redhat.com>]

On 05/30/17 03:34, Junio C Hamano wrote:

> I cannot offhand guess what other places would suffer from such a
> project convention, because I do not work with such a project, but
> you may be able to come up with a list of various places in Git
> where the commit titles are used, and that if there were a mechanism
> to take these commit titles, pass them to your cutomization script,
> which abbreviates these "long common prefixes" to a shorter string,
> and to use the output from that script instead of the actual commit
> title, it would help all of these places.

The problem is that I can't really automate the subject munging. The
concrete subjects in this case were:

> OvmfPkg/QemuFwCfgLib: Implement SEV internal function for SEC phase
> OvmfPkg/QemuFwCfgLib: Implement SEV internal functions for PEI phase
> OvmfPkg/QemuFwCfgLib: Implement SEV internal function for Dxe phase

which got formatted as

> 0010-OvmfPkg-QemuFwCfgLib-Implement-SEV-internal-function.patch
> 0011-OvmfPkg-QemuFwCfgLib-Implement-SEV-internal-function.patch
> 0012-OvmfPkg-QemuFwCfgLib-Implement-SEV-internal-function.patch

and these filenames differ only in the running counter on the left.

The patch subjects themselves aren't overlong (the longest is 68
characters).

At best I could "normalize away" the "OvmfPkg/QemuFwCfgLib" prefix, but
that exact prefix is pretty accidental. Any standalone module (driver or
library instance) in the edk2 project is supposed to be named like this
in patch subjects, so all those prefixes would have to be normalized
somehow.

We generally try to limit subjects (and commit messages in general) to
74 columns. I think for one source of inspiration, we used the kernel
documentation, when setting that limit.
<https://www.kernel.org/doc/Documentation/process/submitting-patches.rst>
says, under section 14, "The canonical patch format",

> The canonical patch subject line is::
>
>     Subject: [PATCH 001/123] subsystem: summary phrase
>
> The canonical patch message body contains the following:
>
>   [...]
>
>   - The body of the explanation, line wrapped at 75 columns, which will
>     be copied to the permanent changelog to describe this patch.

It does not specify the subject length, but perhaps we can apply the
body line length to the subject as well.

So, even in kernel land, if subjects up to 75 columns are permitted, but
FORMAT_PATCH_NAME_MAX is 64, conflicts are possible, at least in theory,
aren't they? With the numbers stripped, of course.

Thanks,
Laszlo