rectorphp/rector · error · InvalidEregException

unescaped metacharacter ")"

Error message

unescaped metacharacter ")"

What it means

EregToPcreTransformer::transform() converts a POSIX ERE pattern (from an ereg()/eregi()/ereg_replace()/split()/spliti() call handled by EregToPregMatchRector) into a PCRE pattern. After the recursive conversion returns, it checks that the whole input was consumed; leftover input means the pattern contained an unbalanced closing ')' at the top level, which is invalid ERE. The resulting InvalidEregException aborts the Rector run on that file.

Solutions

1. Find the failing ereg call (the Rector error output names the file) and fix the literal pattern: escape the parenthesis as '\)' if it is meant literally, or delete the stray one.
2. Re-run rector to confirm the pattern now converts cleanly.
3. If the pattern is intentionally odd, convert that call to preg_match() by hand and let rector skip it.
4. Before large migrations, preflight-scan the codebase for ereg/split calls and validate their literal patterns with EregToPcreTransformer::transform() in a try/catch.

Example fix

// before - unbalanced top-level ')'
ereg('abc)', $subject);

// after - escaped literal parenthesis
ereg('abc\)', $subject); // rector rewrites to: preg_match('#abc\)#m', $subject)

// preflight: validate literal ereg patterns before running rector
use Rector\Php70\EregToPcreTransformer;
use Rector\Php70\Exception\InvalidEregException;
$transformer = new EregToPcreTransformer();
try {
    $transformer->transform($literalPattern, false);
} catch (InvalidEregException $e) {
    echo "Fix pattern before rector run: {$literalPattern} — {$e->getMessage()}\n";
}

function isConvertibleEreg(string $pattern): bool
{
    try {
        (new \Rector\Php70\EregToPcreTransformer())->transform($pattern, false);
        return true;
    } catch (\Rector\Php70\Exception\InvalidEregException $e) {
        return false;
    }
}

try {
    $pcre = $eregToPcreTransformer->transform($pattern, $ignoreCase);
} catch (\Rector\Php70\Exception\InvalidEregException $e) {
    // log the file/pattern, fix the source literal by hand, then re-run rector
    $this->errors[] = [$file, $pattern, $e->getMessage()];
    continue;
}

When it happens

Trigger: Running rector with the Php70 set (or EregToPregMatchRector enabled) at a target PHP >= 7.0 on code containing an ereg-family call whose first argument is a string literal with a stray ')', e.g. `ereg('abc)', $s)` or `split(')|', $s)`. The inner parser breaks out at the ')' and transform() detects $i !== strlen($content).

Common situations: Migrating a legacy PHP 5 codebase to PHP 7+ where hand-written ereg patterns were never validated; patterns built by string concatenation that ended up with an extra ')'; copy-pasted legacy regexes that only worked because ereg tolerated them or were never executed.

Related errors

• a literal null byte in the regex
• an invalid bound
• an invalid character range
• an invalid escape sequence at the end
• an invalid or unsupported character class

AI-assisted analysis of rectorphp/rector@408fcb0ff1 (2026-08-21). Data as JSON: /api/errors/805b12bf3ccec70f. Report an issue: GitHub.

Appendix: source

Thrown at rules/Php70/EregToPcreTransformer.php:81

     * Single type is chosen to prevent every regular with different delimiter.
     */
    public function __construct(string $pcreDelimiter = '#')
    {
        $this->pcreDelimiter = $pcreDelimiter;
    }
    // converts the ERE $s into the PCRE $r. triggers error on any invalid input.
    public function transform(string $content, bool $ignorecase): string
    {
        if ($ignorecase) {
            if (isset($this->icache[$content])) {
                return $this->icache[$content];
            }
        } elseif (isset($this->cache[$content])) {
            return $this->cache[$content];
        }
        [$r, $i] = $this->_ere2pcre($content, 0);
        if ($i !== strlen($content)) {
            throw new InvalidEregException('unescaped metacharacter ")"');
        }
        if ($ignorecase) {
            return $this->icache[$content] = $this->pcreDelimiter . $r . $this->pcreDelimiter . 'mi';
        }
        return $this->cache[$content] = $this->pcreDelimiter . $r . $this->pcreDelimiter . 'm';
    }
    /**
     * Recursively converts ERE into PCRE, starting at the position $i.
     *
     * @return float[]|int[]|string[]
     */
    private function _ere2pcre(string $content, int $i): array
    {
        $r = [''];
        $rr = 0;
        $l = strlen($content);
        $normalizeUnprintableChar = \false;
        while ($i < $l) {

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