Hi Junio, On Mon, 11 Nov 2024, Junio C Hamano wrote: > "Johannes Schindelin via GitGitGadget" <gitgitgadget@xxxxxxxxx> > writes: > > > From: Johannes Schindelin <johannes.schindelin@xxxxxx> > > > > To show a remerge diff, the merge needs to be recreated. For that to > > work, the merge base(s) need to be found, which means that the commits' > > parents have to be traversed until common ancestors are found (if any). > > > > However, one optimization that hails all the way back to > > cb115748ec0d (Some more memory leak avoidance, 2006-06-17) is to release > > the commit's list of parents immediately after showing it. This can break > > the merge base computation. > > > Note that it matters more clearly when traversing the commits in > > reverse: In that instance, if a parent of a merge commit has been shown > > as part of the `git log` command, by the time the merge commit's diff > > needs to be computed, that parent commit's list of parent commits will > > have been set to `NULL` and as a result no merge base will be found. > > Ouch. > > I am curious about "more clearly" in the above, though. I consider these examples less clear, but they are still affected: git show --remerge-diff v2.45.2^0 vs git show --remerge-diff v2.44.2^0 v2.45.2^0 git show --remerge-diff v2.45.1~1 vs git log --topo-order --first-parent --remerge-diff v2.44.2 v2.45.1 Concretely, these diffs should be empty, but are not: git diff --no-index \ <(git show --remerge-diff v2.45.2^0 | sed 1d) \ <(git show --remerge-diff v2.44.2^0 v2.45.2^0 | sed 1,/^commit/d) and git diff --no-index \ <(git show --remerge-diff v2.45.1~1 | grep -v ^commit) \ <(git log --topo-order --first-parent -6 --remerge-diff v2.44.2 v2.45.1 | sed '1,/^commit 1c00f92eb5ee4a48ab615eefa41f2dd6024d43bc/d;/^commit/,$d') No `--reverse` required, not even clock skew. Ciao, Johannes
