From: Elijah Newren <newren@xxxxxxxxx>
This adds the ability to perform real merges rather than just trivial
merges (meaning handling three way content merges, recursive ancestor
consolidation, renames, proper directory/file conflict handling, and so
forth). However, unlike `git merge`, the working tree and index are
left alone and no branch is updated.
The only output is:
- the toplevel resulting tree printed on stdout
- exit status of 0 (clean) or 1 (conflicts present)
This output is meant to be used by some higher level script, perhaps in
a sequence of steps like this:
NEWTREE=$(git merge-tree --write-tree $BRANCH1 $BRANCH2)
test $? -eq 0 || die "There were conflicts..."
NEWCOMMIT=$(git commit-tree $NEWTREE -p $BRANCH1 -p $BRANCH2)
git update-ref $BRANCH1 $NEWCOMMIT
Note that higher level scripts may also want to access the
conflict/warning messages normally output during a merge, or have quick
access to a list of files with conflicts. That is not available in this
preliminary implementation, but subsequent commits will add that
ability.
Signed-off-by: Elijah Newren <newren@xxxxxxxxx>
---
Documentation/git-merge-tree.txt | 74 ++++++++++++++++++++++-----
builtin/merge-tree.c | 55 +++++++++++++++++++-
t/t4301-merge-tree-real.sh | 87 ++++++++++++++++++++++++++++++++
3 files changed, 203 insertions(+), 13 deletions(-)
create mode 100755 t/t4301-merge-tree-real.sh
diff --git a/Documentation/git-merge-tree.txt b/Documentation/git-merge-tree.txt
index 58731c19422..b900bc1362c 100644
--- a/Documentation/git-merge-tree.txt
+++ b/Documentation/git-merge-tree.txt
@@ -3,26 +3,76 @@ git-merge-tree(1)
NAME
----
-git-merge-tree - Show three-way merge without touching index
+git-merge-tree - Perform merge without touching index or working tree
SYNOPSIS
--------
[verse]
-'git merge-tree' <base-tree> <branch1> <branch2>
+'git merge-tree' [--write-tree] <branch1> <branch2>
+'git merge-tree' [--trivial-merge] <base-tree> <branch1> <branch2>
DESCRIPTION
-----------
-Reads three tree-ish, and output trivial merge results and
-conflicting stages to the standard output. This is similar to
-what three-way 'git read-tree -m' does, but instead of storing the
-results in the index, the command outputs the entries to the
-standard output.
-
-This is meant to be used by higher level scripts to compute
-merge results outside of the index, and stuff the results back into the
-index. For this reason, the output from the command omits
-entries that match the <branch1> tree.
+
+Performs a merge, but does not make any new commits and does not read
+from or write to either the working tree or index.
+
+The first form will merge the two branches, doing a full recursive
+merge with rename detection. The rest of this manual (other than the
+next paragraph) describes the first form in more detail -- including
+options, output format, exit status, and usage notes.
+
+The second form is deprecated; it is kept for backward compatibility
+reasons but may be deleted in the future. It will only do a trivial
+merge. It reads three tree-ish, and outputs trivial merge results and
+conflicting stages to the standard output in a semi-diff format.
+Since this was designed for higher level scripts to consume and merge
+the results back into the index, it omits entries that match
+<branch1>. The result of this second form is is similar to what
+three-way 'git read-tree -m' does, but instead of storing the results
+in the index, the command outputs the entries to the standard output.
+This form not only has limited applicability, the output format is
+also difficult to work with, and it will generally be less performant
+than the first form even on successful merges (especially if working
+in large repositories). The remainder of this manual will only
+discuss the first form.
+
+OUTPUT
+------
+
+For either a successful or conflicted merge, the output from
+git-merge-tree is simply one line:
+
+ <OID of toplevel tree>
+
+The printed tree object corresponds to what would be checked out in
+the working tree at the end of `git merge`, and thus may have files
+with conflict markers in them.
+
+EXIT STATUS
+-----------
+
+For a successful, non-conflicted merge, the exit status is 0. When the
+merge has conflicts, the exit status is 1. If the merge is not able to
+complete (or start) due to some kind of error, the exit status is
+something other than 0 or 1.
+
+USAGE NOTES
+-----------
+
+git-merge-tree was written to be low-level plumbing, similar to
+hash-object, mktree, commit-tree, update-ref, and mktag. Thus, it could
+be used as a part of a series of steps such as
+
+ NEWTREE=$(git merge-tree --write-tree $BRANCH1 $BRANCH2)
+ test $? -eq 0 || die "There were conflicts..."
+ NEWCOMMIT=$(git commit-tree $NEWTREE -p $BRANCH1 -p $BRANCH2)
+ git update-ref $BRANCH1 $NEWCOMMIT
+
+However, it does not quite fit into the same category of low-level
+plumbing commands since the possibility of merge conflicts give it a
+much higher chance of the command not succeeding.
GIT
---
diff --git a/builtin/merge-tree.c b/builtin/merge-tree.c
index 33e47cc1534..0c19639594d 100644
--- a/builtin/merge-tree.c
+++ b/builtin/merge-tree.c
@@ -2,6 +2,9 @@
#include "builtin.h"
#include "tree-walk.h"
#include "xdiff-interface.h"
+#include "help.h"
+#include "commit-reach.h"
+#include "merge-ort.h"
#include "object-store.h"
#include "parse-options.h"
#include "repository.h"
@@ -393,7 +396,57 @@ struct merge_tree_options {
static int real_merge(struct merge_tree_options *o,
const char *branch1, const char *branch2)
{
- die(_("real merges are not yet implemented"));
+ struct commit *parent1, *parent2;
+ struct commit_list *common;
+ struct commit_list *merge_bases = NULL;
+ struct commit_list *j;
+ struct merge_options opt;
+ struct merge_result result = { 0 };
+
+ parent1 = get_merge_parent(branch1);
+ if (!parent1)
+ help_unknown_ref(branch1, "merge",
+ _("not something we can merge"));
+
+ parent2 = get_merge_parent(branch2);
+ if (!parent2)
+ help_unknown_ref(branch2, "merge",
+ _("not something we can merge"));
+
+ init_merge_options(&opt, the_repository);
+ /*
+ * TODO: Support subtree and other -X options?
+ if (use_strategies_nr == 1 &&
+ !strcmp(use_strategies[0]->name, "subtree"))
+ opt.subtree_shift = "";
+ for (x = 0; x < xopts_nr; x++)
+ if (parse_merge_opt(&opt, xopts[x]))
+ die(_("Unknown strategy option: -X%s"), xopts[x]);
+ */
+
+ opt.show_rename_progress = 0;
+
+ opt.branch1 = merge_remote_util(parent1)->name; /* or just branch1? */
+ opt.branch2 = merge_remote_util(parent2)->name; /* or just branch2? */
+
+ /*
+ * Get the merge bases, in reverse order; see comment above
+ * merge_incore_recursive in merge-ort.h
+ */
+ common = get_merge_bases(parent1, parent2);
+ if (!common)
+ die(_("refusing to merge unrelated histories"));
+ for (j = common; j; j = j->next)
+ commit_list_insert(j->item, &merge_bases);
+
+ merge_incore_recursive(&opt, merge_bases, parent1, parent2, &result);
+ printf("%s\n", oid_to_hex(&result.tree->object.oid));
+ if (result.clean < 0)
+ die(_("failure to merge"));
+ else if (!result.clean)
+ printf(_("Conflicts!\n"));
+ merge_finalize(&opt, &result);
+ return !result.clean; /* result.clean < 0 handled above */
}
int cmd_merge_tree(int argc, const char **argv, const char *prefix)
diff --git a/t/t4301-merge-tree-real.sh b/t/t4301-merge-tree-real.sh
new file mode 100755
index 00000000000..e03688515c5
--- /dev/null
+++ b/t/t4301-merge-tree-real.sh
@@ -0,0 +1,87 @@
+#!/bin/sh
+
+test_description='git merge-tree --write-tree'
+
+. ./test-lib.sh
+
+# This test is ort-specific
+test "${GIT_TEST_MERGE_ALGORITHM:-ort}" = ort || {
+ skip_all="GIT_TEST_MERGE_ALGORITHM != ort"
+ test_done
+}
+
+test_expect_success setup '
+ test_write_lines 1 2 3 4 5 >numbers &&
+ echo hello >greeting &&
+ echo foo >whatever &&
+ git add numbers greeting whatever &&
+ test_tick &&
+ git commit -m initial &&
+
+ git branch side1 &&
+ git branch side2 &&
+
+ git checkout side1 &&
+ test_write_lines 1 2 3 4 5 6 >numbers &&
+ echo hi >greeting &&
+ echo bar >whatever &&
+ git add numbers greeting whatever &&
+ test_tick &&
+ git commit -m modify-stuff &&
+
+ git checkout side2 &&
+ test_write_lines 0 1 2 3 4 5 >numbers &&
+ echo yo >greeting &&
+ git rm whatever &&
+ mkdir whatever &&
+ >whatever/empty &&
+ git add numbers greeting whatever/empty &&
+ test_tick &&
+ git commit -m other-modifications
+'
+
+test_expect_success 'Content merge and a few conflicts' '
+ git checkout side1^0 &&
+ test_must_fail git merge side2 &&
+ expected_tree=$(cat .git/AUTO_MERGE) &&
+
+ # We will redo the merge, while we are still in a conflicted state!
+ test_when_finished "git reset --hard" &&
+
+ test_expect_code 1 git merge-tree --write-tree side1 side2 >RESULT &&
+ actual_tree=$(head -n 1 RESULT) &&
+
+ # Due to differences of e.g. "HEAD" vs "side1", the results will not
+ # exactly match. Dig into individual files.
+
+ # Numbers should have three-way merged cleanly
+ test_write_lines 0 1 2 3 4 5 6 >expect &&
+ git show ${actual_tree}:numbers >actual &&
+ test_cmp expect actual &&
+
+ # whatever and whatever~<branch> should have same HASHES
+ git rev-parse ${expected_tree}:whatever ${expected_tree}:whatever~HEAD >expect &&
+ git rev-parse ${actual_tree}:whatever ${actual_tree}:whatever~side1 >actual &&
+ test_cmp expect actual &&
+
+ # greeting should have a merge conflict
+ git show ${expected_tree}:greeting >tmp &&
+ cat tmp | sed -e s/HEAD/side1/ >expect &&
+ git show ${actual_tree}:greeting >actual &&
+ test_cmp expect actual
+'
+
+test_expect_success 'Barf on misspelled option, with exit code other than 0 or 1' '
+ # Mis-spell with single "s" instead of double "s"
+ test_expect_code 129 git merge-tree --write-tree --mesages FOOBAR side1 side2 2>expect &&
+
+ grep "error: unknown option.*mesages" expect
+'
+
+test_expect_success 'Barf on too many arguments' '
+ test_expect_code 129 git merge-tree --write-tree side1 side2 side3 2>expect &&
+
+ grep "^usage: git merge-tree" expect
+'
+
+test_done
--
gitgitgadget
