struct commit *p = parent->item;
                const char *hex = NULL;
                if (pp->abbrev)
-                       hex = find_unique_abbrev(p->object.sha1, pp->abbrev);
+                       hex = find_unique_abbrev(p->object.oid.hash, pp->abbrev);
                if (!hex)
-                       hex = sha1_to_hex(p->object.sha1);
+                       hex = oid_to_hex(&p->object.oid);
                parent = parent->next;
 
                strbuf_addf(sb, " %s", hex);
 
        /* these depend on the commit */
        if (!commit->object.parsed)
-               parse_object(commit->object.sha1);
+               parse_object(commit->object.oid.hash);
 
        switch (placeholder[0]) {
        case 'H':               /* commit hash */
                strbuf_addstr(sb, diff_get_color(c->auto_color, DIFF_COMMIT));
-               strbuf_addstr(sb, sha1_to_hex(commit->object.sha1));
+               strbuf_addstr(sb, oid_to_hex(&commit->object.oid));
                strbuf_addstr(sb, diff_get_color(c->auto_color, DIFF_RESET));
                return 1;
        case 'h':               /* abbreviated commit hash */
                        strbuf_addstr(sb, diff_get_color(c->auto_color, DIFF_RESET));
                        return 1;
                }
-               strbuf_addstr(sb, find_unique_abbrev(commit->object.sha1,
+               strbuf_addstr(sb, find_unique_abbrev(commit->object.oid.hash,
                                                     c->pretty_ctx->abbrev));
                strbuf_addstr(sb, diff_get_color(c->auto_color, DIFF_RESET));
                c->abbrev_commit_hash.len = sb->len - c->abbrev_commit_hash.off;
                return 1;
        case 'T':               /* tree hash */
-               strbuf_addstr(sb, sha1_to_hex(commit->tree->object.sha1));
+               strbuf_addstr(sb, oid_to_hex(&commit->tree->object.oid));
                return 1;
        case 't':               /* abbreviated tree hash */
                if (add_again(sb, &c->abbrev_tree_hash))
                        return 1;
-               strbuf_addstr(sb, find_unique_abbrev(commit->tree->object.sha1,
+               strbuf_addstr(sb, find_unique_abbrev(commit->tree->object.oid.hash,
                                                     c->pretty_ctx->abbrev));
                c->abbrev_tree_hash.len = sb->len - c->abbrev_tree_hash.off;
                return 1;
                for (p = commit->parents; p; p = p->next) {
                        if (p != commit->parents)
                                strbuf_addch(sb, ' ');
-                       strbuf_addstr(sb, sha1_to_hex(p->item->object.sha1));
+                       strbuf_addstr(sb, oid_to_hex(&p->item->object.oid));
                }
                return 1;
        case 'p':               /* abbreviated parent hashes */
                        if (p != commit->parents)
                                strbuf_addch(sb, ' ');
                        strbuf_addstr(sb, find_unique_abbrev(
-                                       p->item->object.sha1,
+                                       p->item->object.oid.hash,
                                        c->pretty_ctx->abbrev));
                }
                c->abbrev_parent_hashes.len = sb->len -