Elijah Newren <newren@xxxxxxxxx> writes: > On Fri, Dec 18, 2020 at 6:42 AM Sergey Organov <sorganov@xxxxxxxxx> wrote: >> >> Elijah Newren <newren@xxxxxxxxx> writes: >> >> > On Wed, Dec 16, 2020 at 10:50 AM Sergey Organov <sorganov@xxxxxxxxx> wrote: [...] >> >> diff --git a/log-tree.c b/log-tree.c >> >> index f9385b1dae6f..67060492ca0a 100644 >> >> --- a/log-tree.c >> >> +++ b/log-tree.c >> >> @@ -899,15 +899,21 @@ static int log_tree_diff(struct rev_info *opt, struct commit *commit, struct log >> >> int showed_log; >> >> struct commit_list *parents; >> >> struct object_id *oid; >> >> + int is_merge; >> >> + int regulars_need_diff = opt->diff || opt->diffopt.flags.exit_with_status; >> > >> > So rev_info.diff has changed in meaning from >> > commits-need-to-show-a-diff, to non-merge-commits-need-to-show-a-diff. >> > That's a somewhat subtle semantic shift. Perhaps it's worth adding a >> > comment to the declaration of rev_info.diff to highlight this? (And >> > perhaps even rename the flag?) >> >> No, the meaning of rev_info.diff hopefully didn't change. rev_info.diff >> still enables all the commits to pass further once set. It is still >> exactly the same old condition, just assigned to a variable for reuse. >> My aim was to avoid touching existing logic of this function and only >> add a new functionality when opt->merges_need_diff is set. >> >> It looks like I rather choose confusing name for the variable, and it'd >> be more clear if I'd call this, say: >> >> int need_diff = opt->diff || opt->diffopt.flags.exit_with_status; >> >> ? >> >> What do you think? > > I think need_diff would actually be confusing. It can be false when > you need diffs (e.g. --diff-merges=cc with no -p, because then you'd > need diffs for merge commits and not for non-merge commits). I'd > stick with your original local variable name. > > Perhaps opt->diff hasn't changed meaning and I just had a wrong mental > model in my head for what it meant, but even then what seems like its > obvious purpose given its name is mismatched with what it actually > does. Since you are already changing struct rev_info in this series, > this was more a note that a name change or at least a comment for > opt->diff might be useful. I mean, you asked a couple times on the > previous series for help trying to understand it, and I could only > offer some flailing guesses and Junio responded with a couple bits of > history. Clearly, it isn't very clear and this patch reminded me of > that and made me wonder if we're possibly making it a little harder > for others further down the road to figure out. I still don't see why opt->diff is needed in the first place, and second, why opt->diffopt.flags.exit_with_status check is here? Why whoever sets opt->diffopt.flags.exit_with_status doesn't just set opt->diff as well (provided opt->diff is needed in the first place)? >From the aforementioned discussion it looks like opt->diff is an optimization (maybe a remnant from the times when diff was a separate script), and that apparently there is some code instance somewhere that actually relies on the fact that clearing opt->diff is enough to disable diff machinery (as followed from my experiment of removing the check altogether and then getting only single seemingly unrelated test failing.) Overall, neither have I any idea how to clarify this, nor do I want to bother in this patch series. It'd be nice though if somebody who really does understand diff machinery in Git does the job. Thanks, -- Sergey
