The following issues have been identified by running Psalm with the DBAL 4.0.x-dev:

1. See Modified AbstractPlatform::getLocateExpression() and ::getSubstringExpression() signatures dbal#3494:

   ERROR: PossiblyFalseArgument - lib/Doctrine/ORM/Query/AST/Functions/LocateFunction.php:38:14 - Argument 3 of Doctrine\DBAL\Platforms\AbstractPlatform::getLocateExpression cannot be false, possibly null|string value expected (see https://psalm.dev/104)
               ($this->simpleArithmeticExpression
                   ? $sqlWalker->walkSimpleArithmeticExpression($this->simpleArithmeticExpression)
                   : false
   

2. See Changed the type of $char in AbstractPlatform::getTrimExpression()from string|false to ?string dbal#3491:

    ERROR: InvalidArgument - lib/Doctrine/ORM/Query/AST/Functions/TrimFunction.php:46:50 - Argument 1 of Doctrine\DBAL\Connection::quote expects string, true provided (see https://psalm.dev/004)
                ? $sqlWalker->getConnection()->quote($this->trimChar)
    
    
    ERROR: PossiblyFalseArgument - lib/Doctrine/ORM/Query/AST/Functions/TrimFunction.php:49:72 - Argument 3 of Doctrine\DBAL\Platforms\AbstractPlatform::getTrimExpression cannot be false, possibly null|string value expected (see https://psalm.dev/104)
            return $platform->getTrimExpression($stringPrimary, $trimMode, $trimChar);
   

3. See Connection::quote() can only quote strings dbal#3488:

   ERROR: InvalidArgument - lib/Doctrine/ORM/Query/SqlWalker.php:2197:71 - Argument 1 of Doctrine\DBAL\Connection::quote expects string, Doctrine\ORM\Query\AST\Node provided (see https://psalm.dev/004)
               : (is_numeric($leftExpr) ? $leftExpr : $this->conn->quote($leftExpr));
   
   ERROR: InvalidArgument - lib/Doctrine/ORM/Query/SqlWalker.php:2203:73 - Argument 1 of Doctrine\DBAL\Connection::quote expects string, Doctrine\ORM\Query\AST\Node provided (see https://psalm.dev/004)
               : (is_numeric($rightExpr) ? $rightExpr : $this->conn->quote($rightExpr));