I try use global variable in function. When variable is not defined and I have set error_reporting to E_ALL, PHP doesn't
report, that variable is not defined, but silently define it.

<?php
// Test for use global variable if variable not defined.
// PHP don't write any warning

ini_set("error_reporting", E_ALL);

function test_me(){
	global $test_var;
	return $test_var;
};

// Next line report message "Undefined variable..." - It's ok.
echo "Following message 'Undefined variable...' is OK! It's feature.\n";
echo "Test var (direct test_var): ".$test_var."\n";

// Next line DOESN'T report message "Undefined variable" - It's bug?
echo "Is after this message, message about 'Undefined variable...'? If not - PHP bug\n";
echo "Test var (test_me): ".test_me()."\n";

// Next line DOESN'T report message "Undefined variable" - It's bug?
echo "Test var (direct test_var): ".$test_var."\n";

echo "Now defining test_var\n";
$test_var = "I am here!";
echo "Test var (test_me): ".test_me()."\n";

?>

Is this problem known?