On Mon, Aug 10, 2020 at 08:15:41AM -0700, Junio C Hamano wrote: > > A lot of those patches couldn't be applied cleanly to old > > versions of said software, thus requires some changes from > > developer and they needs to be regenerated from their trimmed > > tree. Because the archive tree has significantly fewer > > objects, the abbreviation in the index line is usually shorter > > than the original patch. Thus, it generates some noise when > > said developers try to compare the new patch with the original > > patch if there's an exact file-hunk match. > > > > Make the object name's abbreviation length configurable to > > lower those noise. > > I agree with Peff that with the above as the sole motivating use > case, the "--full-index" option is the right approach. It is a much > more robust solution than "--abbrev=16 would be long enough for all > project participants to avoid length drift". IOW these four > paragraphs do not argue _for_ this change, at least to me. Yeah, that's what I was getting at: if you care about robust machine-readability, then the full index is the best solution. Reading between the lines, I think the argument may be "using --full-index is too long and therefore ugly, so people like the short-ish names but with a bit of extra safety". There's an extra challenge here, which is that you have to convince the sender to use the extra --abbrev option, even though they themselves won't be the ones running into the problem when applying. But I don't think there's an elegant solution to that (we could just bump the default abbrev everywhere to 12+, which is enough in practice). Though I'm not 100% sure that "git apply" is smart enough to only look at blobs (i.e., if "1234abcd" is ambiguous between a tree and a blob, ignore the tree since patches always apply to blobs). That might be another avenue that would make things more likely to work without anybody having to configure anything. > On the other hand, I think you could argue that "--full-index" is > merely a synonym for "--abbrev=40", and the patch fixes the > inconsistency between the object names on the "index" line, which > can choose only between the default abbrev length and the full > abbrev length, and all the other places we show object names, which > uniformly honor the "--abbrev" option. Yeah, I certainly don't mind the extra flexibility between "full" and "default" for "index" lines. I do wonder if people want to configure the abbreviations for those lines separately from other parts. I don't know that I've ever particularly cared about that flexibility, but the fact that they were set up separately all those years ago makes me think somebody might. -Peff
