Please can you provide a simple test script that shows this.

Forgot to update the status to feedback. Also, the reason I'm asking for an example is that the code for generating warning or exceptions looks really quite unlikely to do both.

https://github.com/php/php-src/blob/528468579b002ff17e3c38d9330da67749fd85ec/ext/pdo/pdo_dbh.c#L149-L165

example:
```
error_reporting(E_ALL);
ini_set('display_errors', 'on');
try {
    $pdo = new PDO('mysql:dbname=qiye;host=100.73.13.5;charset=utf8', 'myroot', 'Hsql1234');
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    $stmt1 = $pdo->prepare('SELECT * FROM auth limit 1');
    $stmt1->execute();
    var_dump($stmt1->fetchAll());

    sleep('30'); // stop the mysql server at this time

    $stmt1 = $pdo->prepare('SELECT * FROM jdb_company_info limit 1');
    $stmt1->execute();
    var_dump($stmt1->fetchAll());
} catch (Throwable $e) {
    var_dump($e->__toString());
}
```

output:

```
array(0) {
}
Warning: PDOStatement::execute(): MySQL server has gone away in /mnt/g/workspace/workspace/qiye/tests/web/test.php on line 21

Warning: PDOStatement::execute(): Error reading result set's header in /mnt/g/workspace/workspace/qiye/tests/web/test.php on line 21
string(240) "PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away in /mnt/g/workspace/workspace/qiye/tests/web/test.php:21
Stack trace:
#0 /mnt/g/workspace/workspace/qiye/tests/web/test.php(21): PDOStatement->execute()
#1 {main}"
```

https://bugs.php.net/bug.php?id=63812 , same problem.

mysqlnd_result.c line 429
php_error_docref(NULL, E_WARNING, "Error reading result set's header");

mysqlnd_wireprotocol.c 
line 298 and line 310
php_error_docref(NULL, E_WARNING, "%s", mysqlnd_server_gone);

7.3.1 this issue actual

This should be fixed since PHP 7.4, by https://github.com/php/php-src/commit/2856afc70e50b85424b2bd2d6653020679160a0b.