unicode string corruption when using PDO_ODBC with FreeTDS 1.3.6 and MS SQL Server 2016

Description

The following code:

<?php
// setup database connection
$u = getenv('DB_USERNAME');
$p = getenv('DB_PASSWORD');
$dsn = 'odbc:testUTF8';
$db = new \PDO($dsn, $u, $p);
$db->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);

$constant_tests = [
    "SELECT CAST(0x72006f017e016f007600fd00 AS nvarchar(10)) AS pink_in_czech_binary_encoded_utf16;",
    "SELECT CAST(0x6b26 AS nvarchar(3)) AS Beamed_Eighth_Notes_binary_encoded_utf16;",
    "SELECT NCHAR(0x266b) AS Beamed_Eighth_Notes_nchar;",
    "SELECT N'♫' AS Beamed_Eighth_Notes_unicode_string_constant;",
    "SELECT N'růžový' AS pink_in_czech_unicode_string_constant;",
];
foreach($constant_tests as $t) {
    fwrite(STDERR, "Running query '$t'...\n");
    var_dump($db->query($t, \PDO::FETCH_ASSOC)->fetchAll());
}

Resulted in this output:

Running query 'SELECT CAST(0x72006f017e016f007600fd00 AS nvarchar(10)) AS pink_in_czech_binary_encoded_utf16;'...
array(1) {
  [0]=>
  array(1) {
    ["pink_in_czech_binary_encoded_utf16"]=>
    string(9) "růžový"
  }
}
Running query 'SELECT CAST(0x6b26 AS nvarchar(3)) AS Beamed_Eighth_Notes_binary_encoded_utf16;'...
array(1) {
  [0]=>
  array(1) {
    ["Beamed_Eighth_Notes_binary_encoded_utf16"]=>
    string(3) "♫"
  }
}
Running query 'SELECT NCHAR(0x266b) AS Beamed_Eighth_Notes_nchar;'...
array(1) {
  [0]=>
  array(1) {
    ["Beamed_Eighth_Notes_nchar"]=>
    string(3) "▒▒"
  }
}
Running query 'SELECT N'♫' AS Beamed_Eighth_Notes_unicode_string_constant;'...
array(1) {
  [0]=>
  array(1) {
    ["Beamed_Eighth_Notes_unicode_string_constant"]=>
    string(3) "▒▒"
  }
}
Running query 'SELECT N'růžový' AS pink_in_czech_unicode_string_constant;'...
array(1) {
  [0]=>
  array(1) {
    ["pink_in_czech_unicode_string_constant"]=>
    string(9) "růžo"
  }
}

But I expected this output instead:

Running query 'SELECT CAST(0x72006f017e016f007600fd00 AS nvarchar(10)) AS pink_in_czech_binary_encoded_utf16;'...
array(1) {
  [0]=>
  array(1) {
    ["pink_in_czech_binary_encoded_utf16"]=>
    string(9) "růžový"
  }
}
Running query 'SELECT CAST(0x6b26 AS nvarchar(3)) AS Beamed_Eighth_Notes_binary_encoded_utf16;'...
array(1) {
  [0]=>
  array(1) {
    ["Beamed_Eighth_Notes_binary_encoded_utf16"]=>
    string(3) "♫"
  }
}
Running query 'SELECT NCHAR(0x266b) AS Beamed_Eighth_Notes_nchar;'...
array(1) {
  [0]=>
  array(1) {
    ["Beamed_Eighth_Notes_nchar"]=>
    string(3) "♫"
  }
}
Running query 'SELECT N'♫' AS Beamed_Eighth_Notes_unicode_string_constant;'...
array(1) {
  [0]=>
  array(1) {
    ["Beamed_Eighth_Notes_unicode_string_constant"]=>
    string(3) "♫"
  }
}
Running query 'SELECT N'růžový' AS pink_in_czech_unicode_string_constant;'...
array(1) {
  [0]=>
  array(1) {
    ["pink_in_czech_unicode_string_constant"]=>
    string(9) "růžový"
  }
}

PHP Version

PHP 8.1.7

Operating System

Debian GNU/Linux testing/bookworm/unstable

まず、提供された PHP スクリプト、PDO::query()、fetchAll() を PDO_ODBC 経由で FreeTDS 1.3.6 および SQL Server 2016 と組み合わせて使用し、問題を再現します。NCHAR と N プレフィックス付き文字列定数について返された値を、期待される Unicode 文字列と比較します。完了の条件は、一覧にあるすべてのクエリが文字化けなしで期待される文字を返すことです。