Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

You can't have nested php-tags, try:

eval('if (1 == 1) { ?>works<? }');

in a sense your example does:
<?php <? if (1 == 1) { ?><? } ?> ?>

Which is wrong

Not enough information was provided for us to be able
to handle this bug. Please re-read the instructions at
http://bugs.php.net/how-to-report.php

If you can provide more information, feel free to add it
to this bug and change the status back to "Open".

Thank you for your interest in PHP.

Hello. I was wrong. My real problem is:

# taken from a user comment

function eval_buffer($string) {
   ob_start();
   eval("$string[2];");
   $return = ob_get_contents();
   ob_end_clean();
   return $return;
}

function eval_print_buffer($string) {
   ob_start();
   eval("print $string[2];");
   $return = ob_get_contents();
   ob_end_clean();
   return $return;
}

function eval_html($string) {
   $string = preg_replace_callback("/(<\?=)(.*?)\?>/si",
                                   "eval_print_buffer",$string);
   return preg_replace_callback("/(<\?php|<\?)(.*?)\?>/si",
                                 "eval_buffer",$string);
}

echo html_eval('<? if (1 == 1) { ?><? } ?>');

And this causes the error. But I don't know if it is the fault of the user-comment-script or if the problem is in eval.

oops, tom is right

Drop this annoying evalHtml crap. Use eval("?>" . $string);!