Merge branch 'tr/describe-advice'

* tr/describe-advice:
describe: when failing, tell the user about options that work

diff --combined builtin-describe.c
index 390c14ec5953447bc2458ba8cc39d35373fdeb51,504d9b120976e7d65d4a229b251e1a006c69e715..d4efb10ddfddedb1671fa91130e5fe78400ad154
--- 1/builtin-describe.c
--- 2/builtin-describe.c
+++ b/builtin-describe.c
@@@ -5,14 -5,12 +5,14 @@@
  #include "builtin.h"
  #include "exec_cmd.h"
  #include "parse-options.h"
 +#include "diff.h"
  
  #define SEEN          (1u<<0)
  #define MAX_TAGS      (FLAG_BITS - 1)
  
  static const char * const describe_usage[] = {
        "git describe [options] <committish>*",
 +      "git describe [options] --dirty",
        NULL
  };
  
@@@ -25,13 -23,6 +25,13 @@@ static int max_candidates = 10
  static int found_names;
  static const char *pattern;
  static int always;
 +static const char *dirty;
 +
 +/* diff-index command arguments to check if working tree is dirty. */
 +static const char *diff_index_args[] = {
 +      "diff-index", "--quiet", "HEAD", "--", NULL
 +};
 +
  
  struct commit_name {
        struct tag *tag;
@@@ -105,8 -96,6 +105,6 @@@ static int get_name(const char *path, c
        if (!all) {
                if (!prio)
                        return 0;
-               if (!tags && prio < 2)
-                       return 0;
        }
        add_to_known_names(all ? path + 5 : path + 10, commit, prio, sha1);
        return 0;
@@@ -193,6 -182,7 +191,7 @@@ static void describe(const char *arg, i
        struct possible_tag all_matches[MAX_TAGS];
        unsigned int match_cnt = 0, annotated_cnt = 0, cur_match;
        unsigned long seen_commits = 0;
+       unsigned int unannotated_cnt = 0;
  
        if (get_sha1(arg, sha1))
                die("Not a valid object name %s", arg);
@@@ -208,8 -198,6 +207,8 @@@
                display_name(n);
                if (longformat)
                        show_suffix(0, n->tag ? n->tag->tagged->sha1 : sha1);
 +              if (dirty)
 +                      printf("%s", dirty);
                printf("\n");
                return;
        }
@@@ -228,7 -216,9 +227,9 @@@
                seen_commits++;
                n = c->util;
                if (n) {
-                       if (match_cnt < max_candidates) {
+                       if (!tags && !all && n->prio < 2) {
+                               unannotated_cnt++;
+                       } else if (match_cnt < max_candidates) {
                                struct possible_tag *t = &all_matches[match_cnt++];
                                t->name = n;
                                t->depth = seen_commits - 1;
@@@ -267,13 -257,17 +268,20 @@@
        if (!match_cnt) {
                const unsigned char *sha1 = cmit->object.sha1;
                if (always) {
 -                      printf("%s\n", find_unique_abbrev(sha1, abbrev));
 +                      printf("%s", find_unique_abbrev(sha1, abbrev));
 +                      if (dirty)
 +                              printf("%s", dirty);
 +                      printf("\n");
                        return;
                }
-               die("cannot describe '%s'", sha1_to_hex(sha1));
+               if (unannotated_cnt)
+                       die("No annotated tags can describe '%s'.\n"
+                           "However, there were unannotated tags: try --tags.",
+                           sha1_to_hex(sha1));
+               else
+                       die("No tags can describe '%s'.\n"
+                           "Try --always, or create some tags.",
+                           sha1_to_hex(sha1));
        }
  
        qsort(all_matches, match_cnt, sizeof(all_matches[0]), compare_pt);
@@@ -305,8 -299,6 +313,8 @@@
        display_name(all_matches[0].name);
        if (abbrev)
                show_suffix(all_matches[0].depth, cmit->object.sha1);
 +      if (dirty)
 +              printf("%s", dirty);
        printf("\n");
  
        if (!last_one)
@@@ -331,9 -323,6 +339,9 @@@ int cmd_describe(int argc, const char *
                           "only consider tags matching <pattern>"),
                OPT_BOOLEAN(0, "always",     &always,
                           "show abbreviated commit object as fallback"),
 +              {OPTION_STRING, 0, "dirty",  &dirty, "mark",
 +                         "append <mark> on dirty working tree (default: \"-dirty\")",
 +               PARSE_OPT_OPTARG, NULL, (intptr_t) "-dirty"},
                OPT_END(),
        };
  
@@@ -374,11 -363,7 +382,11 @@@
                die("No names found, cannot describe anything.");
  
        if (argc == 0) {
 +              if (dirty && !cmd_diff_index(ARRAY_SIZE(diff_index_args) - 1, diff_index_args, prefix))
 +                      dirty = NULL;
                describe("HEAD", 1);
 +      } else if (dirty) {
 +              die("--dirty is incompatible with committishes");
        } else {
                while (argc-- > 0) {
                        describe(*argv++, argc == 0);