> Sometimes "status" does need the actual blobs, if it's going to do > inexact rename detection. Likewise if break-detection is turned on, > though I don't think anything does it by default, and there's (I don't > think) any config option to enable it. > > So something like "git log --name-status -B -M" would probably regress > from this (though only in speed, of course; I do think we can play a > little loose with heuristics since we'd generate the correct answer > either way). > > You could get pretty specific by putting logic inside diffcore_rename(), > which would know if anything is left over after exact rename detection, > but I suspect just checking: > > (options->break_opt != -1 || options->detect_rename) > > in diffcore_std() would be OK in practice. Thanks for taking a look at this patch and for the pointers, especially to rename detection. I investigated and found that in practice, with respect to rename detection, options->detect_rename is insufficient to determine exactly when we need to fetch; we need to fetch when (for example) a file is deleted and another added, but not when a file is merely changed, and these rules are not reflected in options->detect_rename. These rules indeed are in diffcore_rename(), as you mentioned, but putting logic inside diffcore_rename() (or copying the same logic over to diffcore_std()) complicates things for too little benefit, I think. To add to this, rename detection is turned on by default, so it wouldn't even fix the original issue with "status". So I'll abandon this patch, at least until someone finds a use case for diffing with no rename detection on a partial clone and would rather not have a prefetch. > > - Is the whitelist of output_format constants the best? > > I think it could be pared down a bit. For example, --raw doesn't > need the blobs (aside from renames, etc, above). I think the same is > true of --summary. You've already omitted --name-status and --name-only, > which makes sense. > > I think --dirstat, even though it is only showing per-file info, still > relies on the line-level stat info. So it should stay. Thanks for taking a look at this.
