| Message ID | 02c29f920d0d5fde6d85f7b86a69be92e3f0f34d.1643479633.git.gitgitgadget@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | In-core git merge-tree ("Server side merges") | expand |
"Elijah Newren via GitGitGadget" <gitgitgadget@gmail.com> writes: > From: Elijah Newren <newren@gmail.com> > > 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), 1 (conflicts present), anything else > (merge could not be performed; unknown if clean or conflicted) > > 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 It is unclear what NEWTREE has, if anything meaningful, when the command exited with non-zero status. Let's read on. > diff --git a/Documentation/git-merge-tree.txt b/Documentation/git-merge-tree.txt > index 58731c19422..569485815a0 100644 > --- a/Documentation/git-merge-tree.txt > +++ b/Documentation/git-merge-tree.txt > @@ -3,26 +3,73 @@ 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 OK. It is interesting that both apply equally to either command mode ;-) > +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 second form is deprecated and supported only for backward > +compatibility. It will likely be removed in the future, and will not > +be discussed further in this manual. This, especially the deletion of the original description on what trivial merge does, may be premature, especially if it is still "supported for backward compatibility". > +The first form will merge the two branches, doing a real merge. A real > +merge is distinguished from a trivial merge in that it includes: I think this is worth keeping, simply because I do not think you should entirely omit description on the trivial one. But if we were to remove the description on the trivial one, then it is totally meaningless to label the following as "... distinguished from a trivial merge in that". The list of things the real merge command mode does (below) is of course worth having. > + * three way content merges of individual files > + * rename detection > + * proper directory/file conflict handling > + * recursive ancestor consolidation (i.e. when there is more than one > + merge base, creating a virtual merge base by merging the merge bases) > + * etc. > + > +After the merge completes, it will create a new toplevel tree object. > +See `OUTPUT` below for details. > + > +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. So we would leave cruft in the object store, but that is very much on purpose, and the expectation is that the user would commit-tree the tree object and reference it with a ref soon enough before garbage collection prunes them, just like how write-tree is meant to be used. OK. > +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. And the output given to the standard output stream, when the command exits with status higher than 1, is...? "unspecified" is of course an acceptable answer, of course, but I am wondering if it is worth spelling out in the doc. > +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 A notable omission in the above list is 'write-tree'. > +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. I am not sure if that is a fair categorization. It is a fine building block at the lowest level of the tool hierarchy. The primary thing that differentiates plumbing from Porcelain is that the former is a better fit for scripting: doing one thing and one thing well with minimum and stable UI. The complexity of that one thing it does has much less to do with the categorization, and the rate at which users may use the command in a failure-inducing situation has nothing to do with it. The write-tree plumbing command will reliably fail with 100% chance when the index used as its input is unmerged. > @@ -392,7 +395,46 @@ 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-tree", > + _("not something we can merge")); > + > + parent2 = get_merge_parent(branch2); > + if (!parent2) > + help_unknown_ref(branch2, "merge-tree", > + _("not something we can merge")); > + > + init_merge_options(&opt, the_repository); > + > + opt.show_rename_progress = 0; > + > + opt.branch1 = branch1; > + opt.branch2 = 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); > + if (result.clean < 0) > + die(_("failure to merge")); > + puts(oid_to_hex(&result.tree->object.oid)); > + merge_finalize(&opt, &result); > + return !result.clean; /* result.clean < 0 handled above */ > } The implementation is rather straight-forward, if you know how to drive the merge_incore_recursive() helper ;-) > +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 ${actual_tree}:greeting >actual && > + test_cmp expect actual > +' It is somewhat sad that we need to reivent merge test cases over and over, instead of easily reuse an existing one by replacing git checkout one && git merge two with git checkout one && T=$(git merge-tree HEAD two) && C=$(git commit-tree $T -p HEAD -p two) && git reset --hard $C ;-) > +> +test_expect_success 'Barf on misspelled option, with exit code other than 0 or 1' ' > + # Mis-spell with single "s" instead of double "s" > + test_expect_code 129 git merge-tree --write-tree --mesages FOOBAR side1 side2 2>expect && > + > + grep "error: unknown option.*mesages" expect > +' > + > +test_expect_success 'Barf on too many arguments' ' > + test_expect_code 129 git merge-tree --write-tree side1 side2 side3 2>expect && > + > + grep "^usage: git merge-tree" expect > +'
On Wed, Feb 2, 2022 at 1:30 PM Junio C Hamano <gitster@pobox.com> wrote: > > "Elijah Newren via GitGitGadget" <gitgitgadget@gmail.com> writes: > > > From: Elijah Newren <newren@gmail.com> > > > > This adds the ability to perform real merges rather than just trivial > > merges (meaning handling three way content merges, recursive ancestor > > consolidation, renames, proper directory/file conflict handling, and so > > forth). However, unlike `git merge`, the working tree and index are > > left alone and no branch is updated. > > > > The only output is: > > - the toplevel resulting tree printed on stdout > > - exit status of 0 (clean), 1 (conflicts present), anything else > > (merge could not be performed; unknown if clean or conflicted) > > > > This output is meant to be used by some higher level script, perhaps in > > a sequence of steps like this: > > > > NEWTREE=$(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 > > It is unclear what NEWTREE has, if anything meaningful, when the > command exited with non-zero status. Let's read on. > > > diff --git a/Documentation/git-merge-tree.txt b/Documentation/git-merge-tree.txt > > index 58731c19422..569485815a0 100644 > > --- a/Documentation/git-merge-tree.txt > > +++ b/Documentation/git-merge-tree.txt > > @@ -3,26 +3,73 @@ 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 > > OK. It is interesting that both apply equally to either command > mode ;-) > > > +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 second form is deprecated and supported only for backward > > +compatibility. It will likely be removed in the future, and will not > > +be discussed further in this manual. > > This, especially the deletion of the original description on what > trivial merge does, may be premature, especially if it is still > "supported for backward compatibility". I actually extended it, but Dscho suggested removing it entirely -- https://lore.kernel.org/git/nycvar.QRO.7.76.6.2201251804250.2121@tvgsbejvaqbjf.bet/. I can restore it; does that paragraph look good to you (you can see the full thing even if it's split by Dscho's commentary). > > +The first form will merge the two branches, doing a real merge. A real > > +merge is distinguished from a trivial merge in that it includes: > > I think this is worth keeping, simply because I do not think you > should entirely omit description on the trivial one. > > But if we were to remove the description on the trivial one, then it > is totally meaningless to label the following as "... distinguished > from a trivial merge in that". The list of things the real merge > command mode does (below) is of course worth having. > > > + * three way content merges of individual files > > + * rename detection > > + * proper directory/file conflict handling > > + * recursive ancestor consolidation (i.e. when there is more than one > > + merge base, creating a virtual merge base by merging the merge bases) > > + * etc. > > + > > +After the merge completes, it will create a new toplevel tree object. > > +See `OUTPUT` below for details. > > + > > +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. > > So we would leave cruft in the object store, but that is very much > on purpose, and the expectation is that the user would commit-tree > the tree object and reference it with a ref soon enough before > garbage collection prunes them, just like how write-tree is meant to > be used. OK. > > > +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. > > And the output given to the standard output stream, when the command > exits with status higher than 1, is...? "unspecified" is of course > an acceptable answer, of course, but I am wondering if it is worth > spelling out in the doc. Yeah, "unspecified" -- whatever random error the user triggered (couldn't parse arguments, the refs you gave don't exist, the repo you are running from isn't a repo, disk is full, etc.) > > +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 > > A notable omission in the above list is 'write-tree'. Ooh, yeah, I should add that one. > > +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. > > I am not sure if that is a fair categorization. It is a fine > building block at the lowest level of the tool hierarchy. The > primary thing that differentiates plumbing from Porcelain is that > the former is a better fit for scripting: doing one thing and one > thing well with minimum and stable UI. The complexity of that one > thing it does has much less to do with the categorization, and the > rate at which users may use the command in a failure-inducing > situation has nothing to do with it. The write-tree plumbing > command will reliably fail with 100% chance when the index used as > its input is unmerged. > > > @@ -392,7 +395,46 @@ 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-tree", > > + _("not something we can merge")); > > + > > + parent2 = get_merge_parent(branch2); > > + if (!parent2) > > + help_unknown_ref(branch2, "merge-tree", > > + _("not something we can merge")); > > + > > + init_merge_options(&opt, the_repository); > > + > > + opt.show_rename_progress = 0; > > + > > + opt.branch1 = branch1; > > + opt.branch2 = 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); > > + if (result.clean < 0) > > + die(_("failure to merge")); > > + puts(oid_to_hex(&result.tree->object.oid)); > > + merge_finalize(&opt, &result); > > + return !result.clean; /* result.clean < 0 handled above */ > > } > > The implementation is rather straight-forward, if you know how to > drive the merge_incore_recursive() helper ;-) :-) > > > +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 ${actual_tree}:greeting >actual && > > + test_cmp expect actual > > +' > > It is somewhat sad that we need to reivent merge test cases over and > over, instead of easily reuse an existing one by replacing > > git checkout one && > git merge two > > with > > git checkout one && > T=$(git merge-tree HEAD two) && > C=$(git commit-tree $T -p HEAD -p two) && > git reset --hard $C > > ;-) Sorry...I'm afraid I'm not following.
Hi, On Wed, 2 Feb 2022, Elijah Newren wrote: > On Wed, Feb 2, 2022 at 1:30 PM Junio C Hamano <gitster@pobox.com> wrote: > > > > "Elijah Newren via GitGitGadget" <gitgitgadget@gmail.com> writes: > > > > > +Performs a merge, but does not make any new commits and does not read > > > +from or write to either the working tree or index. > > > + > > > +The second form is deprecated and supported only for backward > > > +compatibility. It will likely be removed in the future, and will not > > > +be discussed further in this manual. > > > > This, especially the deletion of the original description on what > > trivial merge does, may be premature, especially if it is still > > "supported for backward compatibility". > > I actually extended it, but Dscho suggested removing it entirely -- > https://lore.kernel.org/git/nycvar.QRO.7.76.6.2201251804250.2121@tvgsbejvaqbjf.bet/. > I can restore it; does that paragraph look good to you (you can see > the full thing even if it's split by Dscho's commentary). I do not necessarily feel strong about keeping the paragraph, but I would appreciate a better rationale for that than "because it was there previously". At this point there cannot be any doubt that the "trivial mode" is worth deprecating and getting rid off because it has been in little or no use. I mean, elsewhere we are overzealously removing stuff "because _core Git_ does not use it", and here we keep something for... reasons? > > > +test_expect_success 'Content merge and a few conflicts' ' > > > + git checkout side1^0 && > > > + test_must_fail git merge side2 && > > > + expected_tree=$(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 ${actual_tree}:greeting >actual && > > > + test_cmp expect actual > > > +' > > > > It is somewhat sad that we need to reivent merge test cases over and > > over, instead of easily reuse an existing one by replacing > > > > git checkout one && > > git merge two > > > > with > > > > git checkout one && > > T=$(git merge-tree HEAD two) && > > C=$(git commit-tree $T -p HEAD -p two) && > > git reset --hard $C > > > > ;-) > > Sorry...I'm afraid I'm not following. I cannot speak for Junio (nor do I want to). Having said that, I interpret the quoted section as a lament on the somewhat repetitive complexity that is required by our tests merely to set up a scenario where we can run the actual command we want to test. If my interpretation is correct, then it is probably fair to suggest using `test_merge` in a setup-type of test case (because that not only runs `git merge` but also tags the result), and then use `git reset --hard <tag>` in subsequent test cases instead of re-running the `checkout && merge` dance. Ciao, Dscho
diff --git a/Documentation/git-merge-tree.txt b/Documentation/git-merge-tree.txt index 58731c19422..569485815a0 100644 --- a/Documentation/git-merge-tree.txt +++ b/Documentation/git-merge-tree.txt @@ -3,26 +3,73 @@ 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> (deprecated) 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 second form is deprecated and supported only for backward +compatibility. It will likely be removed in the future, and will not +be discussed further in this manual. + +The first form will merge the two branches, doing a real merge. A real +merge is distinguished from a trivial merge in that it includes: + + * three way content merges of individual files + * rename detection + * proper directory/file conflict handling + * recursive ancestor consolidation (i.e. when there is more than one + merge base, creating a virtual merge base by merging the merge bases) + * etc. + +After the merge completes, it will create a new toplevel tree object. +See `OUTPUT` below for details. + +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 e98ec8a9f1d..d14c9f6e44e 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" @@ -392,7 +395,46 @@ 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-tree", + _("not something we can merge")); + + parent2 = get_merge_parent(branch2); + if (!parent2) + help_unknown_ref(branch2, "merge-tree", + _("not something we can merge")); + + init_merge_options(&opt, the_repository); + + opt.show_rename_progress = 0; + + opt.branch1 = branch1; + opt.branch2 = 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); + if (result.clean < 0) + die(_("failure to merge")); + puts(oid_to_hex(&result.tree->object.oid)); + 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-write-tree.sh b/t/t4301-merge-tree-write-tree.sh new file mode 100755 index 00000000000..66c3eaf2021 --- /dev/null +++ b/t/t4301-merge-tree-write-tree.sh @@ -0,0 +1,88 @@ +#!/bin/sh + +test_description='git merge-tree --write-tree' + +. ./test-lib.sh + +# This test is ort-specific +if test "${GIT_TEST_MERGE_ALGORITHM}" != "ort" +then + skip_all="GIT_TEST_MERGE_ALGORITHM != ort" + test_done +fi + +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