brian m. carlson wrote: > On Mon, Jun 11, 2018 at 12:01:03PM -0700, Jonathan Nieder wrote: >> 1. Hash to be used for command output to the terminal >> 2. Hash used in pack files >> 3. Additional hashes (beyond (2)) that we can look up using the >> translation table >> 4. Additional hashes (beyond (1)) accepted in input from the command >> line and stdin >> >> In principle, (1) and (4) would be globals, and (2) and (3) would be >> tied to the repository. I think this is always what Duy was hinting Here, by 'always' I meant 'also'. Sorry for the confusion. >> at. >> >> All that said, as long as there is some notion of (1) and (4), I'm >> excited. :) Details of how they are laid out in memory are less >> important. > > I'm happy to hear suggestions on how this should or shouldn't work. I'm > seeing these things in my head, but it can be helpful to have feedback > about what people expect out of the code before I spend a bunch of time > writing it. So far you're doing pretty well. :) I just noticed that I have some copy-edits for the hash-function-transition doc from last year that I hadn't sent out yet (oops). I'll send them tonight or tomorrow morning. [...] >> brian m. carlson wrote: >>> The transition plan anticipates a stage 1 where accept only SHA-1 on >>> input and produce only SHA-1 on output, but store in NewHash. As I've >>> worked with our tests, I've realized such an implementation is not >>> entirely possible. We have various tools that expect to accept invalid >>> object IDs, and obviously there's no way to have those continue to work. >> >> Can you give an example? Do you mean commands like "git mktree"? > > I mean situations like git update-index. We allow the user to insert > any old invalid value (and in fact check that the user can do this). > t0000 does this, for example. I think we can forbid this in the new mode (using a test prereq to ensure the relevant tests don't get run). Likewise for the similar functionality in "git mktree" and "git hash-object -w". >> You can always use something like e.g. "doubled SHA-1" as a proof of >> concept, but I agree that it's nice to be able to avoid some churn by >> using an actual hash function that we're likely to switch to. > > I have a hash that I've been using, but redoing the work would be less > enjoyable. I'd rather write the tests only once if I can help it. Thanks for the test fixes so far that make most of the test suite hash-agnostic! For t0000, yeah, there's no way around having to hard-code the new hash there. Thanks, Jonathan
