Merge branch 'rs/tag-null-pointer-arith-fix'

Code clean-up.

* rs/tag-null-pointer-arith-fix:
tag: avoid NULL pointer arithmetic

diff --combined tag.c
index 7e10acfb6ef1673e783e0a42e1b8810a6e2eff06,a3ffffdbfad8022937028a986f690a6e11002531..fcbe012f7a2203e198dac9eac03aa9dab999f334
--- 1/tag.c
--- 2/tag.c
+++ b/tag.c
@@@ -33,7 -33,7 +33,7 @@@ static int run_gpg_verify(const char *b
        return ret;
  }
  
 -int gpg_verify_tag(const unsigned char *sha1, const char *name_to_report,
 +int gpg_verify_tag(const struct object_id *oid, const char *name_to_report,
                unsigned flags)
  {
        enum object_type type;
@@@ -41,20 -41,20 +41,20 @@@
        unsigned long size;
        int ret;
  
 -      type = sha1_object_info(sha1, NULL);
 +      type = sha1_object_info(oid->hash, NULL);
        if (type != OBJ_TAG)
                return error("%s: cannot verify a non-tag object of type %s.",
                                name_to_report ?
                                name_to_report :
 -                              find_unique_abbrev(sha1, DEFAULT_ABBREV),
 +                              find_unique_abbrev(oid->hash, DEFAULT_ABBREV),
                                typename(type));
  
 -      buf = read_sha1_file(sha1, &type, &size);
 +      buf = read_sha1_file(oid->hash, &type, &size);
        if (!buf)
                return error("%s: unable to read file.",
                                name_to_report ?
                                name_to_report :
 -                              find_unique_abbrev(sha1, DEFAULT_ABBREV));
 +                              find_unique_abbrev(oid->hash, DEFAULT_ABBREV));
  
        ret = run_gpg_verify(buf, size, flags);
  
@@@ -142,13 -142,13 +142,13 @@@ int parse_tag_buffer(struct tag *item, 
        bufptr = nl + 1;
  
        if (!strcmp(type, blob_type)) {
-               item->tagged = &lookup_blob(&oid)->object;
+               item->tagged = (struct object *)lookup_blob(&oid);
        } else if (!strcmp(type, tree_type)) {
-               item->tagged = &lookup_tree(&oid)->object;
+               item->tagged = (struct object *)lookup_tree(&oid);
        } else if (!strcmp(type, commit_type)) {
-               item->tagged = &lookup_commit(&oid)->object;
+               item->tagged = (struct object *)lookup_commit(&oid);
        } else if (!strcmp(type, tag_type)) {
-               item->tagged = &lookup_tag(&oid)->object;
+               item->tagged = (struct object *)lookup_tag(&oid);
        } else {
                error("Unknown type %s", type);
                item->tagged = NULL;