Description:
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This problem only occurs sometimes. I only had it for 5-8 times, but it really drives me crazy for now. I can't explain myself to be such a bad programmer, so it must be a bug. 


It occurs sometimes in if clauses like:

if (isset($a) || isset($b)) {
	// do something
}

..and PHP returns 
"Fatal error: Call to undefined function  () in /index.php on line XX"


If the if-clause was "((isset($a)) || (isset($b)))" it helped to remove the additional parenthesis, and do "(isset($a) || isset($b))2 instead.
Also the error was eliminated in some cases by adding another side to the expressions, like "((isset($a)==true) || (isset($b)==false))".

But for now I'm really fed up with this:

$a=isset($_GET['action']);
$b=$a && (strpos($_GET['action'], 'admin')===false);

if (($a) || ($b)) {
	echo "if it works or not doesn't matter; the question is if it can be parsed";
}

I tried everything but I can't get that expression to work. In antoher case i really wrote TWO if-clauses with only one statement that called one and the same function. Working an above code also revaled that $b becomes unexptected, when writing:

if ($a || $b) {
	echo "if it works or not doesn't matter; the question is if it can be parsed";
}
Parse error: parse error, unexpected T_VARIABLE in /index.php on line 353


Anyway, that error occurs only in some bunch of code and cannot really be reproduced with a single file containing above code-snippets.

I appreciate appropiate workarounds for that problem ;)


PHP Version doesn't matter. I had the problem with PHP 4.x and still have it with 5.04 and 5.1RC3.