PHP eval and capturing errors (as much as possible)

Since PHP 7 eval() will generate a ParseError exception for syntax errors:

try {    $result = eval($code);} catch (ParseError $e) {    // Report error somehow}

In PHP 5 eval() will generate a parse error, which is special-cased to not abort execution (as parse errors would usually do). However, it also cannot be caught through an error handler. A possibility is to catch the printed error message, assuming that display_errors=1:

ob_start();$result = eval($code);if ('' !== $error = ob_get_clean()) {    // Report error somehow}

I've found a good alternative/answer to my question.

First of, let me start by saying that nikic's suggestion works when I set error_reporting(E_ALL); notices are shown in PHP output, and thanks to OB, they can be captured.

Next, I've found this very useful code:

/** * Check the syntax of some PHP code. * @param string $code PHP code to check. * @return boolean|array If false, then check was successful, otherwise an array(message,line) of errors is returned. */function php_syntax_error($code){    if(!defined("CR"))        define("CR","\r");    if(!defined("LF"))        define("LF","\n") ;    if(!defined("CRLF"))        define("CRLF","\r\n") ;    $braces=0;    $inString=0;    foreach (token_get_all('<?php ' . $code) as $token) {        if (is_array($token)) {            switch ($token[0]) {                case T_CURLY_OPEN:                case T_DOLLAR_OPEN_CURLY_BRACES:                case T_START_HEREDOC: ++$inString; break;                case T_END_HEREDOC:   --$inString; break;            }        } else if ($inString & 1) {            switch ($token) {                case '`': case '\'':                case '"': --$inString; break;            }        } else {            switch ($token) {                case '`': case '\'':                case '"': ++$inString; break;                case '{': ++$braces; break;                case '}':                    if ($inString) {                        --$inString;                    } else {                        --$braces;                        if ($braces < 0) break 2;                    }                    break;            }        }    }    $inString = @ini_set('log_errors', false);    $token = @ini_set('display_errors', true);    ob_start();    $code = substr($code, strlen('<?php '));    $braces || $code = "if(0){{$code}\n}";    if (eval($code) === false) {        if ($braces) {            $braces = PHP_INT_MAX;        } else {            false !== strpos($code,CR) && $code = strtr(str_replace(CRLF,LF,$code),CR,LF);            $braces = substr_count($code,LF);        }        $code = ob_get_clean();        $code = strip_tags($code);        if (preg_match("'syntax error, (.+) in .+ on line (\d+)$'s", $code, $code)) {            $code[2] = (int) $code[2];            $code = $code[2] <= $braces                ? array($code[1], $code[2])                : array('unexpected $end' . substr($code[1], 14), $braces);        } else $code = array('syntax error', 0);    } else {        ob_end_clean();        $code = false;    }    @ini_set('display_errors', $token);    @ini_set('log_errors', $inString);    return $code;}

Seems it easily does exactly what I need (yay)!

How to test for parse errors inside eval():

$result = @eval($evalcode . "; return true;");

If $result == false, $evalcode has a parse error and does not execute the 'return true' part. Obviously $evalcode must not return itself something, but with this trick you can test for parse errors in expressions effectively...