Merge branch 'mg/name-rev-debug' into pu

"git describe --debug --contains" did not add any meaningful
information, even though without "--contains" it did.

* mg/name-rev-debug:
  describe: pass --debug down to name-rev
  name-rev: provide debug output

Author: gitster

Documentation/git-name-rev.txt

@@ -42,6 +42,11 @@ OPTIONS
 --all::
 	List all commits reachable from all refs
 
+--debug::
+	Verbosely display information about the searching strategy
+	being employed to standard error.  The symbolic name will still
+	be printed to standard out.
+
 --stdin::
 	Transform stdin by substituting all the 40-character SHA-1
 	hexes (say $hex) with "$hex ($rev_name)".  When used with

builtin/describe.c

@@ -486,6 +486,8 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
 				 NULL);
 		if (always)
 			argv_array_push(&args, "--always");
+		if (debug)
+			argv_array_push(&args, "--debug");
 		if (!all) {
 			argv_array_push(&args, "--tags");
 			for_each_string_list_item(item, &patterns)

builtin/name-rev.c

@@ -18,6 +18,10 @@ typedef struct rev_name {
 
 static timestamp_t cutoff = TIME_MAX;
 
+static const char *prio_names[] = {
+	N_("head"), N_("lightweight"), N_("annotated"),
+};
+
 /* How many generations are maximally preferred over _one_ merge traversal? */
 #define MERGE_TRAVERSAL_WEIGHT 65535
 
@@ -59,10 +63,19 @@ static int is_better_name(struct rev_name *name,
 	return 0;
 }
 
+struct name_ref_data {
+	int tags_only;
+	int name_only;
+	int debug;
+	struct string_list ref_filters;
+	struct string_list exclude_filters;
+	struct object_array *revs;
+};
+
 static void name_rev(struct commit *commit,
 		const char *tip_name, timestamp_t taggerdate,
 		int generation, int distance, int from_tag,
-		int deref)
+		int deref, struct name_ref_data *data)
 {
 	struct rev_name *name = (struct rev_name *)commit->util;
 	struct commit_list *parents;
@@ -76,6 +89,7 @@ static void name_rev(struct commit *commit,
 
 	if (deref) {
 		tip_name = to_free = xstrfmt("%s^0", tip_name);
+		from_tag += 1;
 
 		if (generation)
 			die("generation: %d, but deref?", generation);
@@ -88,6 +102,36 @@ static void name_rev(struct commit *commit,
 	} else if (is_better_name(name, tip_name, taggerdate,
 				  generation, distance, from_tag)) {
 copy_data:
+		if (data->debug) {
+			int i;
+			static int label_width = -1;
+			static int name_width = -1;
+			if (label_width < 0) {
+				int w;
+				for (i = 0; i < ARRAY_SIZE(prio_names); i++) {
+					w = strlen(_(prio_names[i]));
+					if (label_width < w)
+						label_width = w;
+				}
+			}
+			if (name_width < 0) {
+				int w;
+				for (i = 0; i < data->revs->nr; i++) {
+					w = strlen(data->revs->objects[i].name);
+					if (name_width < w)
+						name_width = w;
+				}
+			}
+			for (i = 0; i < data->revs->nr; i++)
+				if (!oidcmp(&commit->object.oid,
+					    &data->revs->objects[i].item->oid))
+					fprintf(stderr, " %-*s %8d %-*s %s~%d\n",
+						label_width,
+						_(prio_names[from_tag]),
+						distance, name_width,
+						data->revs->objects[i].name,
+						tip_name, generation);
+		}
 		name->tip_name = tip_name;
 		name->taggerdate = taggerdate;
 		name->generation = generation;
@@ -115,11 +159,11 @@ static void name_rev(struct commit *commit,
 
 			name_rev(parents->item, new_name, taggerdate, 0,
 				 distance + MERGE_TRAVERSAL_WEIGHT,
-				 from_tag, 0);
+				 from_tag, 0, data);
 		} else {
 			name_rev(parents->item, tip_name, taggerdate,
 				 generation + 1, distance + 1,
-				 from_tag, 0);
+				 from_tag, 0, data);
 		}
 	}
 }
@@ -149,13 +193,6 @@ static const char *name_ref_abbrev(const char *refname, int shorten_unambiguous)
 	return refname;
 }
 
-struct name_ref_data {
-	int tags_only;
-	int name_only;
-	struct string_list ref_filters;
-	struct string_list exclude_filters;
-};
-
 static struct tip_table {
 	struct tip_table_entry {
 		struct object_id oid;
@@ -239,7 +276,6 @@ static int name_ref(const char *path, const struct object_id *oid, int flags, vo
 	}
 
 	add_to_tip_table(oid, path, can_abbreviate_output);
-
 	while (o && o->type == OBJ_TAG) {
 		struct tag *t = (struct tag *) o;
 		if (!t->tagged)
@@ -256,7 +292,7 @@ static int name_ref(const char *path, const struct object_id *oid, int flags, vo
 			taggerdate = ((struct commit *)o)->date;
 		path = name_ref_abbrev(path, can_abbreviate_output);
 		name_rev(commit, xstrdup(path), taggerdate, 0, 0,
-			 from_tag, deref);
+			 from_tag, deref, data);
 	}
 	return 0;
 }
@@ -389,7 +425,7 @@ int cmd_name_rev(int argc, const char **argv, const char *prefix)
 {
 	struct object_array revs = OBJECT_ARRAY_INIT;
 	int all = 0, transform_stdin = 0, allow_undefined = 1, always = 0, peel_tag = 0;
-	struct name_ref_data data = { 0, 0, STRING_LIST_INIT_NODUP, STRING_LIST_INIT_NODUP };
+	struct name_ref_data data = { 0, 0, 0, STRING_LIST_INIT_NODUP, STRING_LIST_INIT_NODUP };
 	struct option opts[] = {
 		OPT_BOOL(0, "name-only", &data.name_only, N_("print only names (no SHA-1)")),
 		OPT_BOOL(0, "tags", &data.tags_only, N_("only use tags to name the commits")),
@@ -399,6 +435,7 @@ int cmd_name_rev(int argc, const char **argv, const char *prefix)
 				   N_("ignore refs matching <pattern>")),
 		OPT_GROUP(""),
 		OPT_BOOL(0, "all", &all, N_("list all commits reachable from all refs")),
+		OPT_BOOL(0, "debug", &data.debug, N_("debug search strategy on stderr")),
 		OPT_BOOL(0, "stdin", &transform_stdin, N_("read from stdin")),
 		OPT_BOOL(0, "undefined", &allow_undefined, N_("allow to print `undefined` names (default)")),
 		OPT_BOOL(0, "always",     &always,
@@ -464,6 +501,7 @@ int cmd_name_rev(int argc, const char **argv, const char *prefix)
 
 	if (cutoff)
 		cutoff = cutoff - CUTOFF_DATE_SLOP;
+	data.revs = &revs;
 	for_each_ref(name_ref, &data);
 
 	if (transform_stdin) {