On Tue, 26 May 2026 at 18:27, Branko Čibej <[email protected]> wrote:
> On 26. 5. 26 18:09, [email protected] wrote: > > Author: ivan > Date: Tue May 26 16:09:14 2026 > New Revision: 1934646 > > Log: > Resolve compiler warning (C4312: 'type cast': conversion from 'unsigned int' > to 'void *' of greater size). > > * subversion/libsvn_repos/rev_hunt.c > (find_interesting_revisions): Use "1" instead of 0xdeadbeef as non-null > pointer for hashtable. > > Modified: > subversion/trunk/subversion/libsvn_repos/rev_hunt.c > > Modified: subversion/trunk/subversion/libsvn_repos/rev_hunt.c > ============================================================================== > --- subversion/trunk/subversion/libsvn_repos/rev_hunt.c Tue May 26 > 15:32:31 2026 (r1934645) > +++ subversion/trunk/subversion/libsvn_repos/rev_hunt.c Tue May 26 > 16:09:14 2026 (r1934646) > @@ -1198,7 +1198,7 @@ find_interesting_revisions(apr_array_hea > svn_hash_sets(duplicate_path_revs, > apr_psprintf(result_pool, "%s:%ld", path_rev->path, > path_rev->revnum), > - (void *)0xdeadbeef); > + "1"); > > if (path_rev->revnum <= start) > break; > > > That dead beef was there because we're using the hash table as a set, not > a dictionary; only the keys matter. It was intentionally an invalid pointer > so that the code would crash in a very recognisable way (better than NULL) > if someone ever tried to dereference the value from the hash table. If > you're fixing some useless compiler warning – frankly, a promotion that > doesn't lose data shouldn't warn at all, this is C, after all – then at > least replace it with NULL instead of a valid pointer that could one day > hide a real bug. > > Yes, I understand that not everyone likes my approach to defence against > incorrect code. :) > > It's common for Subversion code to use "" as placeholder in apr_hash_t when it used as set. Some examples: subversion\libsvn_client\conflicts.c(13293):svn_hash_sets(cswb->unresolved_tree_conflicts, tc_abspath, ""); subversion\libsvn_client\conflicts.c(13322):svn_hash_sets(unresolved_tree_conflicts, tc_abspath, ""); subversion\libsvn_delta\editor.c(497):svn_hash_sets(editor->pending_incomplete_children, child, ""); ... Another common pattern is to use 1 as pointer. For example: subversion\libsvn_ra_serf\options.c(268):apr_hash_set(session->supported_posts, "create-txn", 10, (void *)1); subversion\libsvn_ra_serf\options.c(340):svn_hash_sets(session->supported_posts, post_val, (void *)1); ... The 0xdeadbeef was used in only one place. I also would like to note that 0xdeadbeef value is not special and can be valid pointer. But I'd rather not split hairs on this (rather minor, to my opinion) topic. I have reverted the change in r1934681. -- Ivan Zhakov
