On Mon, May 01, 2017 at 12:34:38PM +0200, Ævar Arnfjörð Bjarmason wrote: > > I don't know if we would want to be extra paranoid about patch-ids. > > There is no helping: > > > > git rev-list HEAD | git diff-tree --stdin -p | git patch-id --stable > > > > because diff-tree doesn't know that it's trying for "--stable" output. > > But the diffs we compute internally for patch-id could disable the > > heuristics. I'm not sure if those matter, though. AFAIK those are used > > only for internal comparisons within a single program. I.e., we never > > compare them against input from the user, nor do we output them to the > > user. So they'll change, but I don't think anybody would care. > > I have a few-million row table with commit_id as one column & patch_id > as another. I.e. a commit -> patch_id mapping. Thanks for this data point. It's always interesting to hear about unforeseen uses of the tools. Out of curiosity, how do you generate the patch-ids? Is it with something like diff-tree piped to patch-id? I do feel a bit sad about breaking this case (or at the very least forcing you to set an option to retain cross-version compatibility). But my gut says that we don't want to lock ourselves into never changing the diff algorithm (and I'm sure we've done it inadvertently a few times over the years; even the recent switch to turning on renames would have had that impact). -Peff