Fix slow analysis on return with a big OR condition

Author: staabm

src/Analyser/SpecifiedTypes.php

@@ -3,13 +3,16 @@
 namespace PHPStan\Analyser;
 
 use PhpParser\Node\Expr;
+use PHPStan\Type\GeneralizePrecision;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
+use PHPStan\Type\UnionType;
 use function array_key_exists;
 use function array_merge;
 
 final class SpecifiedTypes
 {
+	private const MAX_SURE_NOT_TYPES = 8;
 
 	private bool $overwrite = false;
 
@@ -179,6 +182,10 @@ public function unionWith(SpecifiedTypes $other): self
 				continue;
 			}
 
+			if ($type instanceof UnionType && count($type->getTypes()) >= self::MAX_SURE_NOT_TYPES) {
+				continue;
+			}
+
 			$sureNotTypeUnion[$exprString] = [
 				$exprNode,
 				TypeCombinator::union($type, $other->sureNotTypes[$exprString][1]),