[PATCH 6/7] merge-ort: upon merge abort, only show messages causing the abort

["Elijah Newren via GitGitGadget" <gitgitgadget@gmail.com>]

From: Elijah Newren <newren@gmail.com>

When something goes wrong enough that we need to abort early and not
even attempt merging the remaining files, it probably does not make
sense to report conflicts messages for the subset of files we processed
before hitting the fatal error.  Instead, only show the messages
associated with paths where we hit the fatal error.  Also, print these
messages to stderr rather than stdout.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-ort.c | 76 ++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 52 insertions(+), 24 deletions(-)

diff --git a/merge-ort.c b/merge-ort.c
index 462bc6fb6e1..5410dec2b4f 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -543,10 +543,24 @@ enum conflict_and_info_types {
 	CONFLICT_SUBMODULE_HISTORY_NOT_AVAILABLE,
 	CONFLICT_SUBMODULE_MAY_HAVE_REWINDS,
 	CONFLICT_SUBMODULE_NULL_MERGE_BASE,
-	CONFLICT_SUBMODULE_CORRUPT,
+
+	/* INSERT NEW ENTRIES HERE */
+
+	/*
+	 * Keep this entry after all regular conflict and info types; only
+	 * errors (failures causing immediate abort of the merge) should
+	 * come after this.
+	 */
+	NB_REGULAR_CONFLICT_TYPES,
+
+	/*
+	 * Something is seriously wrong; cannot even perform merge;
+	 * Keep this group _last_ other than NB_CONFLICT_TYPES
+	 */
+	ERROR_SUBMODULE_CORRUPT,
 
 	/* Keep this entry _last_ in the list */
-	NB_CONFLICT_TYPES,
+	NB_TOTAL_TYPES,
 };
 
 /*
@@ -597,8 +611,10 @@ static const char *type_short_descriptions[] = {
 		"CONFLICT (submodule may have rewinds)",
 	[CONFLICT_SUBMODULE_NULL_MERGE_BASE] =
 		"CONFLICT (submodule lacks merge base)",
-	[CONFLICT_SUBMODULE_CORRUPT] =
-		"CONFLICT (submodule corrupt)"
+
+	/* Something is seriously wrong; cannot even perform merge */
+	[ERROR_SUBMODULE_CORRUPT] =
+		"ERROR (submodule corrupt)",
 };
 
 struct logical_conflict_info {
@@ -762,7 +778,8 @@ static void path_msg(struct merge_options *opt,
 
 	/* Sanity checks */
 	assert(omittable_hint ==
-	       !starts_with(type_short_descriptions[type], "CONFLICT") ||
+	       (!starts_with(type_short_descriptions[type], "CONFLICT") &&
+		!starts_with(type_short_descriptions[type], "ERROR")) ||
 	       type == CONFLICT_DIR_RENAME_SUGGESTED);
 	if (opt->record_conflict_msgs_as_headers && omittable_hint)
 		return; /* Do not record mere hints in headers */
@@ -1817,9 +1834,9 @@ static int merge_submodule(struct merge_options *opt,
 	/* check whether both changes are forward */
 	ret2 = repo_in_merge_bases(&subrepo, commit_o, commit_a);
 	if (ret2 < 0) {
-		path_msg(opt, CONFLICT_SUBMODULE_CORRUPT, 0,
+		path_msg(opt, ERROR_SUBMODULE_CORRUPT, 0,
 			 path, NULL, NULL, NULL,
-			 _("Failed to merge submodule %s "
+			 _("error: failed to merge submodule %s "
 			   "(repository corrupt)"),
 			 path);
 		ret = -1;
@@ -1828,9 +1845,9 @@ static int merge_submodule(struct merge_options *opt,
 	if (ret2 > 0)
 		ret2 = repo_in_merge_bases(&subrepo, commit_o, commit_b);
 	if (ret2 < 0) {
-		path_msg(opt, CONFLICT_SUBMODULE_CORRUPT, 0,
+		path_msg(opt, ERROR_SUBMODULE_CORRUPT, 0,
 			 path, NULL, NULL, NULL,
-			 _("Failed to merge submodule %s "
+			 _("error: failed to merge submodule %s "
 			   "(repository corrupt)"),
 			 path);
 		ret = -1;
@@ -1848,7 +1865,7 @@ static int merge_submodule(struct merge_options *opt,
 	/* Case #1: a is contained in b or vice versa */
 	ret2 = repo_in_merge_bases(&subrepo, commit_a, commit_b);
 	if (ret2 < 0) {
-		path_msg(opt, CONFLICT_SUBMODULE_CORRUPT, 0,
+		path_msg(opt, ERROR_SUBMODULE_CORRUPT, 0,
 			 path, NULL, NULL, NULL,
 			 _("Failed to merge submodule %s "
 			   "(repository corrupt)"),
@@ -1867,9 +1884,9 @@ static int merge_submodule(struct merge_options *opt,
 	}
 	ret2 = repo_in_merge_bases(&subrepo, commit_b, commit_a);
 	if (ret2 < 0) {
-		path_msg(opt, CONFLICT_SUBMODULE_CORRUPT, 0,
+		path_msg(opt, ERROR_SUBMODULE_CORRUPT, 0,
 			 path, NULL, NULL, NULL,
-			 _("Failed to merge submodule %s "
+			 _("error: failed to merge submodule %s "
 			   "(repository corrupt)"),
 			 path);
 		ret = -1;
@@ -1901,9 +1918,9 @@ static int merge_submodule(struct merge_options *opt,
 					 &merges);
 	switch (parent_count) {
 	case -1:
-		path_msg(opt, CONFLICT_SUBMODULE_CORRUPT, 0,
+		path_msg(opt, ERROR_SUBMODULE_CORRUPT, 0,
 			 path, NULL, NULL, NULL,
-			 _("Failed to merge submodule %s "
+			 _("error: failed to merge submodule %s "
 			   "(repository corrupt)"),
 			 path);
 		ret = -1;
@@ -4646,6 +4663,7 @@ void merge_display_update_messages(struct merge_options *opt,
 	struct hashmap_iter iter;
 	struct strmap_entry *e;
 	struct string_list olist = STRING_LIST_INIT_NODUP;
+	FILE *o = stdout;
 
 	if (opt->record_conflict_msgs_as_headers)
 		BUG("Either display conflict messages or record them as headers, not both");
@@ -4662,6 +4680,10 @@ void merge_display_update_messages(struct merge_options *opt,
 	}
 	string_list_sort(&olist);
 
+	/* Print to stderr if we hit errors rather than just conflicts */
+	if (result->clean < 0)
+		o = stderr;
+
 	/* Iterate over the items, printing them */
 	for (int path_nr = 0; path_nr < olist.nr; ++path_nr) {
 		struct string_list *conflicts = olist.items[path_nr].util;
@@ -4669,25 +4691,31 @@ void merge_display_update_messages(struct merge_options *opt,
 			struct logical_conflict_info *info =
 				conflicts->items[i].util;
 
+			/* On failure, ignore regular conflict types */
+			if (result->clean < 0 &&
+			    info->type < NB_REGULAR_CONFLICT_TYPES)
+				continue;
+
 			if (detailed) {
-				printf("%lu", (unsigned long)info->paths.nr);
-				putchar('\0');
+				fprintf(o, "%lu", (unsigned long)info->paths.nr);
+				fputc('\0', o);
 				for (int n = 0; n < info->paths.nr; n++) {
-					fputs(info->paths.v[n], stdout);
-					putchar('\0');
+					fputs(info->paths.v[n], o);
+					fputc('\0', o);
 				}
-				fputs(type_short_descriptions[info->type],
-				      stdout);
-				putchar('\0');
+				fputs(type_short_descriptions[info->type], o);
+				fputc('\0', o);
 			}
-			puts(conflicts->items[i].string);
+			fputs(conflicts->items[i].string, o);
+			fputc('\n', o);
 			if (detailed)
-				putchar('\0');
+				fputc('\0', o);
 		}
 	}
 	string_list_clear(&olist, 0);
 
-	print_submodule_conflict_suggestion(&opti->conflicted_submodules);
+	if (result->clean >= 0)
+		print_submodule_conflict_suggestion(&opti->conflicted_submodules);
 
 	/* Also include needed rename limit adjustment now */
 	diff_warn_rename_limit("merge.renamelimit",
-- 
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