set-head: better output for --auto

Currently, set-head --auto will print a message saying "remote/HEAD set
to branch", which implies something was changed.

Change the output of --auto, so the output actually reflects what was
done: a) set a previously unset HEAD, b) change HEAD because remote
changed or c) no updates. As a fourth output, if HEAD is changed from
a previous value that was not a remote branch, explicitly call attention
to this fact.

Signed-off-by: Bence Ferdinandy <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: ferdinandyb

builtin/remote.c

@@ -1399,10 +1399,34 @@ static int show(int argc, const char **argv, const char *prefix)
 	return result;
 }
 
+static void report_auto(const char *remote, const char *head_name,
+			struct strbuf *buf_prev) {
+	struct strbuf buf_prefix = STRBUF_INIT;
+	const char *prev_head = NULL;
+
+	strbuf_addf(&buf_prefix, "refs/remotes/%s/", remote);
+	skip_prefix(buf_prev->buf, buf_prefix.buf, &prev_head);
+
+	if (prev_head && !strcmp(prev_head, head_name))
+		printf("'%s/HEAD' is unchanged and points to '%s'\n",
+			remote, head_name);
+	else if (prev_head)
+		printf("'%s/HEAD' has changed from '%s' and now points to '%s'\n",
+			remote, prev_head, head_name);
+	else if (buf_prev->len == 0)
+		printf("'%s/HEAD' is now created and points to '%s'\n",
+			remote, head_name);
+	else
+		printf("'%s/HEAD' used to point to '%s' "
+			"(which is unusual), but now points to '%s'\n",
+			remote, buf_prev->buf, head_name);
+}
+
 static int set_head(int argc, const char **argv, const char *prefix)
 {
 	int i, opt_a = 0, opt_d = 0, result = 0;
-	struct strbuf buf = STRBUF_INIT, buf2 = STRBUF_INIT;
+	struct strbuf buf = STRBUF_INIT, buf2 = STRBUF_INIT,
+		buf_prev = STRBUF_INIT;
 	char *head_name = NULL;
 	struct ref_store *refs = get_main_ref_store(the_repository);
 
@@ -1445,15 +1469,17 @@ static int set_head(int argc, const char **argv, const char *prefix)
 		/* make sure it's valid */
 		if (!refs_ref_exists(refs, buf2.buf))
 			result |= error(_("Not a valid ref: %s"), buf2.buf);
-		else if (refs_update_symref(refs, buf.buf, buf2.buf, "remote set-head", NULL))
+		else if (refs_update_symref(refs, buf.buf, buf2.buf, "remote set-head", &buf_prev))
 			result |= error(_("Could not setup %s"), buf.buf);
-		else if (opt_a)
-			printf("%s/HEAD set to %s\n", argv[0], head_name);
+		else if (opt_a) {
+			report_auto(argv[0], head_name, &buf_prev);
+		}
 		free(head_name);
 	}
 
 	strbuf_release(&buf);
 	strbuf_release(&buf2);
+	strbuf_release(&buf_prev);
 	return result;
 }
 

t/t5505-remote.sh

@@ -429,12 +429,51 @@ test_expect_success 'set-head --auto' '
 	)
 '
 
+test_expect_success 'set-head --auto detects creation' '
+	(
+		cd test &&
+		rm .git/refs/remotes/origin/HEAD &&
+		git remote set-head --auto origin >output &&
+		echo "'\''origin/HEAD'\'' is now created and points to '\''main'\''" >expect &&
+		test_cmp expect output
+	)
+'
+
+test_expect_success 'set-head --auto detects no change' '
+	(
+		cd test &&
+		git remote set-head --auto origin >output &&
+		echo "'\''origin/HEAD'\'' is unchanged and points to '\''main'\''" >expect &&
+		test_cmp expect output
+	)
+'
+
+test_expect_success 'set-head --auto detects change' '
+	(
+		cd test &&
+		echo "ref: refs/remotes/origin/ahead" >.git/refs/remotes/origin/HEAD &&
+		git remote set-head --auto origin >output &&
+		echo "'\''origin/HEAD'\'' has changed from '\''ahead'\'' and now points to '\''main'\''" >expect &&
+		test_cmp expect output
+	)
+'
+
+test_expect_success 'set-head --auto detects strange ref' '
+	(
+		cd test &&
+		echo "ref: refs/heads/main" >.git/refs/remotes/origin/HEAD &&
+		git remote set-head --auto origin >output &&
+		echo "'\''origin/HEAD'\'' used to point to '\''refs/heads/main'\'' (which is unusual), but now points to '\''main'\''" >expect &&
+		test_cmp expect output
+	)
+'
+
 test_expect_success 'set-head --auto has no problem w/multiple HEADs' '
 	(
 		cd test &&
 		git fetch two "refs/heads/*:refs/remotes/two/*" &&
 		git remote set-head --auto two >output 2>&1 &&
-		echo "two/HEAD set to main" >expect &&
+		echo "'\''two/HEAD'\'' is now created and points to '\''main'\''" >expect &&
 		test_cmp expect output
 	)
 '
@@ -453,6 +492,17 @@ test_expect_success 'set-head explicit' '
 	)
 '
 
+
+test_expect_success 'set-head --auto reports change' '
+	(
+		cd test &&
+		git remote set-head origin side2 &&
+		git remote set-head --auto origin >output 2>&1 &&
+		echo "'\''origin/HEAD'\'' has changed from '\''side2'\'' and now points to '\''main'\''" >expect &&
+		test_cmp expect output
+	)
+'
+
 cat >test/expect <<EOF
 Pruning origin
 URL: $(pwd)/one