Re: [PATCH 08/12] merge-ort: provide a merge_get_conflicted_files() helper function

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

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Hi Elijah,

[after this update, I will shut up until you chime in, promise!]

On Mon, 6 Jun 2022, Johannes Schindelin wrote:

> On Sun, 5 Jun 2022, Johannes Schindelin wrote:
>
> > On Sat, 4 Jun 2022, Johannes Schindelin wrote:
> >
> > > It would be great if you could have a quick look over the commits I
> > > added on top of your branch, to see whether things make more or less
> > > sense to you. But if you're too busy elsewhere, I am one of the best
> > > persons to understand that, too.
> >
> > Hopefully I will get this into a reviewable shape before you get to
> > looking at it, so that your time is spent more wisely than what I
> > asked for ;-)
>
> I hope to find some time to work on this more tomorrow; If not, I will
> get back to the project on Wednesday and push it further.

I did get a chance, and polished the patch series a bit. I also rebased it
onto the current tip of Git's main branch, mainly to address some merge
conflicts preemptively. The result is pushed up to
https://github.com/dscho/git/tree/js/in-core-merge-tree. This is the
range-diff relative to `newren/wip-for-in-core-merge-tree`:

-- snip --
 1:  cccb3888070 <  -:  ----------- tmp-objdir: new API for creating temporary writable databases
 2:  4e44121c2d7 <  -:  ----------- tmp-objdir: disable ref updates when replacing the primary odb
 3:  0b94724311d <  -:  ----------- show, log: provide a --remerge-diff capability
 4:  f06de6c1b2f <  -:  ----------- log: clean unneeded objects during `log --remerge-diff`
 5:  8d6c3d48f0e <  -:  ----------- ll-merge: make callers responsible for showing warnings
 6:  de8e8f88fa4 <  -:  ----------- merge-ort: capture and print ll-merge warnings in our preferred fashion
 7:  6b535a4d55a <  -:  ----------- merge-ort: mark a few more conflict messages as omittable
 8:  e2441608c63 <  -:  ----------- merge-ort: format messages slightly different for use in headers
 9:  62734beb693 <  -:  ----------- diff: add ability to insert additional headers for paths
10:  17eccf7e0d6 <  -:  ----------- show, log: include conflict/warning messages in --remerge-diff headers
11:  b3e7656cfc6 <  -:  ----------- merge-ort: mark conflict/warning messages from inner merges as omittable
12:  ea5df61cf35 <  -:  ----------- diff-merges: avoid history simplifications when diffing merges
13:  4a7cd5542bb =  1:  8fb51817ed4 merge-tree: rename merge_trees() to trivial_merge_trees()
14:  4780ff6784d =  2:  8e0a79fa1ad merge-tree: move logic for existing merge into new function
15:  60253745f5c =  3:  baf0950bcb6 merge-tree: add option parsing and initial shell for real merge function
16:  f8266d39c1b =  4:  697470e50ae merge-tree: implement real merges
17:  6629af14919 =  5:  069af1ecc30 merge-ort: split out a separate display_update_messages() function
18:  17b57efb714 =  6:  53c92a5d8d9 merge-tree: support including merge messages in output
19:  4c8f42372dd =  7:  67a728d35f0 merge-ort: provide a merge_get_conflicted_files() helper function
25:  8fe5be07cd0 !  8:  6419487e26b merge-ort: remove command-line-centric submodule message from merge-ort
    @@ merge-ort.c: static int merge_submodule(struct merge_options *opt,
      		strbuf_release(&sb);
      		break;
      	default:
    +
    + ## t/t6437-submodule-merge.sh ##
    +@@ t/t6437-submodule-merge.sh: test_expect_success 'merging should conflict for non fast-forward' '
    + 	(cd merge-search &&
    + 	 git checkout -b test-nonforward b &&
    + 	 (cd sub &&
    +-	  git rev-parse sub-d > ../expect) &&
    ++	  git rev-parse --short sub-d > ../expect) &&
    + 	  if test "$GIT_TEST_MERGE_ALGORITHM" = ort
    + 	  then
    + 		test_must_fail git merge c >actual
20:  7b1ee417f3d !  9:  c92b81e7366 merge-tree: provide a list of which files have conflicts
    @@ builtin/merge-tree.c: static int real_merge(struct merge_tree_options *o,
     +		string_list_clear(&conflicted_files, 1);
     +	}
      	if (o->show_messages) {
    - 		printf("\n");
    +-		printf("\n");
    ++		putchar(line_termination);
      		merge_display_update_messages(&opt, &result);
    + 	}
    + 	merge_finalize(&opt, &result);
     @@ builtin/merge-tree.c: int cmd_merge_tree(int argc, const char **argv, const char *prefix)

      	/* Do the relevant type of merge */
21:  f1231a8fbc8 = 10:  d7360f58f16 merge-tree: provide easy access to `ls-files -u` style info
 -:  ----------- > 11:  b53ef9c2116 merge-ort: store messages in a list, not in a single strbuf
 -:  ----------- > 12:  b16d570d248 merge-ort: make `path_messages` a strmap to a string_list
 -:  ----------- > 13:  b575a6b5f8a merge-ort: store more specific conflict information
 -:  ----------- > 14:  4f245cc28ae merge-ort: optionally produce machine-readable output
22:  22297e6ce75 ! 15:  6a369f837be merge-tree: allow `ls-files -u` style info to be NUL terminated
    @@ builtin/merge-tree.c: static int real_merge(struct merge_tree_options *o,
      	if (!result.clean) {
      		struct string_list conflicted_files = STRING_LIST_INIT_NODUP;
      		const char *last = NULL;
    -@@ builtin/merge-tree.c: static int real_merge(struct merge_tree_options *o,
    - 		string_list_clear(&conflicted_files, 1);
    - 	}
    - 	if (o->show_messages) {
    --		printf("\n");
    -+		putchar(line_termination);
    - 		merge_display_update_messages(&opt, &result);
    - 	}
    - 	merge_finalize(&opt, &result);
     @@ builtin/merge-tree.c: int cmd_merge_tree(int argc, const char **argv, const char *prefix)
      			    N_("do a trivial merge only"), MODE_TRIVIAL),
      		OPT_BOOL(0, "messages", &o.show_messages,
    @@ t/t4301-merge-tree-write-tree.sh: test_expect_success 'Check conflicted oids and
     +
     +	test_expect_code 1 git merge-tree --write-tree -z tweak1 side2 >out &&
     +	anonymize_hash out >actual &&
    ++	printf "\\n" >>actual &&
     +
     +	# Expected results:
     +	#   "greeting" should merge with conflicts
    @@ t/t4301-merge-tree-write-tree.sh: test_expect_success 'Check conflicted oids and
     +
     +	EOF
     +
    -+	cat <<-EOF >>expect &&
    -+	Auto-merging greeting
    -+	CONFLICT (content): Merge conflict in greeting
    -+	CONFLICT (file/directory): directory in the way of whatever from tweak1; moving it to whatever~tweak1 instead.
    -+	CONFLICT (modify/delete): whatever~tweak1 deleted in side2 and modified in tweak1.  Version tweak1 of whatever~tweak1 left in tree.
    -+	Auto-merging Αυτά μου φαίνονται κινέζικα
    -+	CONFLICT (content): Merge conflict in Αυτά μου φαίνονται κινέζικα
    ++	q_to_nul <<-EOF >>expect &&
    ++	1QgreetingQAuto-mergingQAuto-merging greeting
    ++	Q1QgreetingQCONFLICT (contents)QCONFLICT (content): Merge conflict in greeting
    ++	Q2Qwhatever~tweak1QwhateverQCONFLICT (file/directory)QCONFLICT (file/directory): directory in the way of whatever from tweak1; moving it to whatever~tweak1 instead.
    ++	Q1Qwhatever~tweak1QCONFLICT (modify/delete)QCONFLICT (modify/delete): whatever~tweak1 deleted in side2 and modified in tweak1.  Version tweak1 of whatever~tweak1 left in tree.
    ++	Q1QΑυτά μου φαίνονται κινέζικαQAuto-mergingQAuto-merging Αυτά μου φαίνονται κινέζικα
    ++	Q1QΑυτά μου φαίνονται κινέζικαQCONFLICT (contents)QCONFLICT (content): Merge conflict in Αυτά μου φαίνονται κινέζικα
    ++	Q
     +	EOF
     +
     +	test_cmp expect actual
23:  db73c6dd823 = 16:  47146dd59dd merge-tree: add a --allow-unrelated-histories flag
24:  d58a7c7a9f6 ! 17:  3ce28f6fd97 git-merge-tree.txt: add a section on potentional usage mistakes
    @@ Documentation/git-merge-tree.txt: with linkgit:git-merge[1]:
     +<<IM,Informational messages>> section has the necessary info, though it
     +is not designed to be machine parseable.
     +
    ++Do NOT assume that each paths from <<CFI,Conflicted file info>>, and
    ++the logical conflicts in the <<IM,Informational messages>> have a
    ++one-to-one mapping, nor that there is a one-to-many mapping, nor a
    ++many-to-one mapping.  Many-to-many mappings exist, meaning that each
    ++path can have many logical conflict types in a single merge, and each
    ++logical conflict type can affect many paths.
    ++
     +Do NOT assume all filenames listed in the <<IM,Informational messages>>
     +section had conflicts.  Messages can be included for files that have no
     +conflicts, such as "Auto-merging <file>".
26:  78e1243eca1 <  -:  ----------- WIP
-- snap --

I am pretty happy with the current state of the patches, and hope that we
can push this patch series over the finish line.

If you can think of anything I can do to help with this, please do let me
know, I am _very_ interested in getting this done, and finally am in a
position to help.

Ciao,
Dscho