Equality checks in query.php can break permalinks

[agharbeia]

According to this ​http://wordpress.org/support/topic/122702,
there is bug in the way WP 2.2 handles permalinks consisting only of date/time elements.

The blog in which the problem manifests uses the permalink structure /%year%/%monthnum%/%day%/%hour%%minute%%second%

In this case WP fails to uniquely identify a post whose %hour% permalink tag resolves to zero, and resorts instead to displaying the archive page for the calendar day in which the post referred to by the permalink was published, which in turn means that is_single() will always resolve to false and that no single post page can ever be obtained.

Posts having anything other than zero in their %hour% of publication will resolve normally.

Please note that unlike some people might first assume, this permalink structure worked in versions before 2.2. WordPress was indeed able to handle permalink structures which do not have neither %post_id% nor %postname%

This is due to all the instances in query.php where it's checking for things like this:

if ( '' != $q['hour'] ) ...

The empty string == zero, in php. Evidence:

<?php if ('' == 0) echo "equal"; else echo "not equal"; ?>

All these checks need to be changed from != to !== in order to test for identity instead of equality.

Note that he would get the same result for minute == 0 or second == 0 as well. There are also possibly other equality checks that can result in broken links like this.

Should be a simple search+replace.

Can't make a patch at the moment, however I made a modified copy of query.php, and the original poster says it works. It can be found here:
​http://wordpress.pastebin.ca/579658

Patched based on Otto42's modified query.php file (for trunk)

We have to fix it in trunk before we can even consider fixing it in 2.2.2

4499-trunk.diff is a diff based on Otto42's modified query.php

Look good?

Looks good to me, mark. It may not fix all of the possibles of this issue, but it does fix the hour/minute/second ones.

(In [5848]) Allow for hour/minute/second values in the QS that evaluate as false (like 0). Props Otto42 and agharbeia. fixes #4499