alias: show the call history when an alias is looping

diff --git a/git.c b/git.c
index 15727c17f1823a96e4623fcda59eb104668acf60..a20eb4fa1536c0d81a12cc09340d8dff3a373e82 100644 (file)
--- a/git.c
+++ b/git.c
@@ -675,6 +675,7 @@ static int run_argv(int *argcp, const char ***argv)
 {
        int done_alias = 0;
        struct string_list cmd_list = STRING_LIST_INIT_NODUP;
+       struct string_list_item *seen;
 
        while (1) {
                /*
@@ -692,9 +693,21 @@ static int run_argv(int *argcp, const char ***argv)
                /* .. then try the external ones */
                execv_dashed_external(*argv);
 
-               if (unsorted_string_list_has_string(&cmd_list, *argv[0])) {
+               seen = unsorted_string_list_lookup(&cmd_list, *argv[0]);
+               if (seen) {
+                       int i;
+                       struct strbuf sb = STRBUF_INIT;
+                       for (i = 0; i < cmd_list.nr; i++) {
+                               struct string_list_item *item = &cmd_list.items[i];
+
+                               strbuf_addf(&sb, "\n  %s", item->string);
+                               if (item == seen)
+                                       strbuf_addstr(&sb, " <==");
+                               else if (i == cmd_list.nr - 1)
+                                       strbuf_addstr(&sb, " ==>");
+                       }
                        die(_("alias loop detected: expansion of '%s' does"
-                             " not terminate"), cmd_list.items[0].string);
+                             " not terminate:%s"), cmd_list.items[0].string, sb.buf);
                }
 
                string_list_append(&cmd_list, *argv[0]);