get_sha1: warn about full or short object names that look like refs

diff --git a/sha1_name.c b/sha1_name.c
index 95003c77ea9a0ee240d60bc7958bb48245b14ad4..502d107a5e427f61374a97d36ebc392f9619f3ad 100644 (file)
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -435,12 +435,31 @@ static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned l
 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 {
        static const char *warn_msg = "refname '%.*s' is ambiguous.";
+       static const char *object_name_msg = N_(
+       "Git normally never creates a ref that ends with 40 hex characters\n"
+       "because it will be ignored when you just specify 40-hex. These refs\n"
+       "may be created by mistake. For example,\n"
+       "\n"
+       "  git checkout -b $br $(git rev-parse ...)\n"
+       "\n"
+       "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
+       "examine these refs and maybe delete them. Turn this message off by\n"
+       "running \"git config advice.object_name_warning false\"");
+       unsigned char tmp_sha1[20];
        char *real_ref = NULL;
        int refs_found = 0;
        int at, reflog_len;
 
-       if (len == 40 && !get_sha1_hex(str, sha1))
+       if (len == 40 && !get_sha1_hex(str, sha1)) {
+               refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
+               if (refs_found > 0 && warn_ambiguous_refs) {
+                       warning(warn_msg, len, str);
+                       if (advice_object_name_warning)
+                               fprintf(stderr, "%s\n", _(object_name_msg));
+               }
+               free(real_ref);
                return 0;
+       }
 
        /* basic@{time or number or -number} format to query ref-log */
        reflog_len = at = 0;
@@ -481,7 +500,9 @@ static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
        if (!refs_found)
                return -1;
 
-       if (warn_ambiguous_refs && refs_found > 1)
+       if (warn_ambiguous_refs &&
+           (refs_found > 1 ||
+            !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
                warning(warn_msg, len, str);
 
        if (reflog_len) {