Re: [PATCH] merge-tree: accept 3 trees as arguments
From: Junio C Hamano <hidden>
Date: 2024-01-26 16:01:49
"Johannes Schindelin via GitGitGadget" [off-list ref] writes:
From: Johannes Schindelin <redacted> When specifying a merge base explicitly, there is actually no good reason why the inputs need to be commits: that's only needed if the merge base has to be deduced from the commit graph.
yes, Yes, YES, YEAHHHHH!
I was asked to implement this at $dayjob and it seems like a feature
that might be useful to other users, too.Yup, I think it is an obvious building block for machinery to perform any mergy operation to grow history. Many of the time you may have a commit, but requiring them to be commits when you know you will not do a virtual ancestor synthesis smells fundamentally wrong. Thanks for fixing it.
---merge-base=<commit>:: +--merge-base=<tree-ish>:: Instead of finding the merge-bases for <branch1> and <branch2>, specify a merge-base for the merge, and specifying multiple bases is currently not supported. This option is incompatible with `--stdin`. ++ +As the merge-base is provided directly, <branch1> and <branch2> do not need +o specify commits; it is sufficient if they specify trees.
"... do not need to specify commits; trees are enough"?
quoted hunk
diff --git a/builtin/merge-tree.c b/builtin/merge-tree.c index 3bdec53fbe5..cbd8e15af6d 100644 --- a/builtin/merge-tree.c +++ b/builtin/merge-tree.c@@ -429,35 +429,43 @@ static int real_merge(struct merge_tree_options *o, struct merge_options opt; copy_merge_options(&opt, &o->merge_options); - parent1 = get_merge_parent(branch1); - if (!parent1) - help_unknown_ref(branch1, "merge-tree", - _("not something we can merge")); - - parent2 = get_merge_parent(branch2); - if (!parent2) - help_unknown_ref(branch2, "merge-tree", - _("not something we can merge")); - opt.show_rename_progress = 0; opt.branch1 = branch1; opt.branch2 = branch2; if (merge_base) { - struct commit *base_commit; struct tree *base_tree, *parent1_tree, *parent2_tree; - base_commit = lookup_commit_reference_by_name(merge_base); - if (!base_commit) - die(_("could not lookup commit '%s'"), merge_base); + /* + * We actually only need the trees because we already + * have a merge base. + */ + struct object_id base_oid, head_oid, merge_oid; + + if (repo_get_oid_treeish(the_repository, merge_base, &base_oid)) + die(_("could not parse as tree '%s'"), merge_base); + base_tree = parse_tree_indirect(&base_oid); + if (repo_get_oid_treeish(the_repository, branch1, &head_oid)) + die(_("could not parse as tree '%s'"), branch1); + parent1_tree = parse_tree_indirect(&head_oid); + if (repo_get_oid_treeish(the_repository, branch2, &merge_oid)) + die(_("could not parse as tree '%s'"), branch2); + parent2_tree = parse_tree_indirect(&merge_oid); opt.ancestor = merge_base; - base_tree = repo_get_commit_tree(the_repository, base_commit); - parent1_tree = repo_get_commit_tree(the_repository, parent1); - parent2_tree = repo_get_commit_tree(the_repository, parent2); merge_incore_nonrecursive(&opt, base_tree, parent1_tree, parent2_tree, &result); } else { + parent1 = get_merge_parent(branch1); + if (!parent1) + help_unknown_ref(branch1, "merge-tree", + _("not something we can merge")); + + parent2 = get_merge_parent(branch2); + if (!parent2) + help_unknown_ref(branch2, "merge-tree", + _("not something we can merge")); + /* * Get the merge bases, in reverse order; see comment above * merge_incore_recursive in merge-ort.h
OK. The changes here look quite straight-forward.
quoted hunk
diff --git a/t/t4301-merge-tree-write-tree.sh b/t/t4301-merge-tree-write-tree.sh index 12ac4368736..71f21bb834f 100755 --- a/t/t4301-merge-tree-write-tree.sh +++ b/t/t4301-merge-tree-write-tree.sh@@ -945,4 +945,12 @@ test_expect_success 'check the input format when --stdin is passed' ' test_cmp expect actual ' +test_expect_success '--merge-base with tree OIDs' ' + git merge-tree --merge-base=side1^ side1 side3 >tree && + tree=$(cat tree) && + git merge-tree --merge-base=side1^^{tree} side1^{tree} side3^{tree} >tree2 && + tree2=$(cat tree2) && + test $tree = $tree2 +'
You do not need $tree and $tree2 variables that would make it harder to diagnose a failure case when we break merge-tree. You have tree and tree2 as files, and I think it is sufficient to do git merge-tree ... >result-from-commits && git merge-tree ... >result-from-trees && test_cmp result-from-commits result-from-trees (no, I am not suggesting to rename these tree and tree2 files; I just needed them to be descriptive in my illustration to show what is going on to myself). Thanks.