TYPO3 Core

when replacing the IF construction in the LDAP extension with the following line:
require_once(PATH_tslib.'class.tslib_content.php');
does this help? Require_once should care for not including files twice.

Okay, this might help.
However I'm not very familiar with Typo3 so I don't know which way is the right way to go. Is there a suggestion about which path to use? I don't really know why there are two files in the first place. I assume there is a good reason and maybe I should read the archive first.
I think, the fix I suggested has the advantage, that it should remove this problem for all extensions and should not do any harm.

tslib is normally a symbolic link to typo3/sysext/cms/tslib (where this is possible). I don't know if PHP checks for symlinks when a require_once is done.
Does somebody else using the LDAP extensions have the same problem? I don't use it, that's why I can't say anything about it.
Greets, Sebastian

As I wrote, at least two people in the (main, english) mailinglist reported the problem first. Maybe two weeks ago or something. There even were some suggesion to solve the problem but they did not help.
I will ask the author of the LDAP-extension as well, I do have some patches for him anyways.

For me the problem could be solved by Sebastians suggestion.

...on a windows installation, that is.

... but then in the backend, the ldap_sync module didn't work anymore.

I worked around this using a sledgehammer:

if(!class_exists('tslib_cObj')) {
if (PATH_tslib == "PATH_tslib") {
define("PATH_tslib", t3lib_extmgm::extPath('cms','tslib/'));
}
debug(PATH_tslib);
require_once(PATH_tslib.'class.tslib_content.php');
}

Resolved, unable to reproduce: ldap login works fine for me, everything is ok.