rectorphp/rector · error · ShouldNotHappenException

"%s" rule is deprecated, as it creates unreadable code with

Error message

"%s" rule is deprecated, as it creates unreadable code with messy checks; refactor the value to a sole type instead

What it means

Rector\Strict\Rector\Empty_\DisallowedEmptyRuleFixerRector is deprecated: refactor() throws Rector\Exception\ShouldNotHappenException on the first Empty_ or BooleanNot node. The rule tried to satisfy the strict/rule 'no empty()' policy by replacing empty()/!empty() with explicit type checks, but the generated comparisons were messy and hard to read. The accepted answer is to refactor the value so it has a single unambiguous type, after which a plain comparison replaces empty().

Source

Thrown at rules/Strict/Rector/Empty_/DisallowedEmptyRuleFixerRector.php:65

        return $items === [];
    }
}
CODE_SAMPLE
, [self::TREAT_AS_NON_EMPTY => \false])]);
    }
    /**
     * @return array<class-string<Node>>
     */
    public function getNodeTypes(): array
    {
        return [Empty_::class, BooleanNot::class];
    }
    /**
     * @param Empty_|BooleanNot $node
     */
    public function refactor(Node $node): ?Node
    {
        throw new ShouldNotHappenException(sprintf('"%s" rule is deprecated, as it creates unreadable code with messy checks; refactor the value to a sole type instead', self::class));
    }
}

View on GitHub (pinned to 408fcb0ff1)

Solutions

Remove DisallowedEmptyRuleFixerRector from rector.php.
Refactor the offending value to a single concrete type (e.g. always an array), then replace empty($x) with an explicit comparison like $x === [].
Enforce the 'no empty()' policy in code review or a sniff that only reports, instead of an automated rewrite.

Example fix

// before (rector.php)
->withRules([DisallowedEmptyRuleFixerRector::class])

// after (rector.php) - removed; fix types by hand

// before
if (empty($items)) {
    return [];
}

// after - $items is guaranteed to be an array
if ($items === []) {
    return [];
}

Defensive patterns

Strategy: validation

Validate before calling

use Rector\Strict\Rector\Empty_\DisallowedEmptyRuleFixerRector;

$rules = [/* your list */ DisallowedEmptyRuleFixerRector::class];
if (in_array(DisallowedEmptyRuleFixerRector::class, $rules, true)) {
    throw new InvalidArgumentException('Rule deprecated; refactor the value to a sole type instead of rewriting empty()');
}

Try / catch

try {
    exit($rectorApplication->run());
} catch (\Rector\Exception\ShouldNotHappenException $e) {
    if (str_contains($e->getMessage(), 'DisallowedEmptyRuleFixerRector')) {
        fwrite(STDERR, 'Remove the rule; fix variable types so empty() can become an explicit comparison.' . PHP_EOL);
        exit(1);
    }
    throw $e;
}

Prevention

Enforce 'no empty()' with a detector (slevomat coding standard sniff) that only reports, instead of an automated rewriter.
Narrow variable types first (PHPStan), then replace empty() manually with the exact comparison.
After rector upgrades, remove 'strict' bundle rules that now throw instead of rewriting.

When it happens

Trigger: The rule is listed in rector.php (often via an old custom 'strict' rule list) and the analyzed code contains empty(...) or !empty(...) or negated expressions; refactor() throws on the first Empty_/BooleanNot match.

Common situations: Enabling a copied 'strict' rule bundle after a rector upgrade; CI failing as soon as it scans a file using empty(); teams trying to ban empty() project-wide via rector.

Related errors

AI-assisted analysis of rectorphp/rector@408fcb0ff1 (2026-08-21). Data as JSON: /api/errors/66f79ef4eeaa6cbe. Report an issue: GitHub.