get_html_translation_table() inconsistent results with ENT_XHTML?

Description

The following code:

<?php

print_r(get_html_translation_table(HTML_SPECIALCHARS, ENT_QUOTES | ENT_SUBSTITUTE | ENT_XHTML, "UTF-8"));
print_r(get_html_translation_table(HTML_ENTITIES, ENT_QUOTES | ENT_SUBSTITUTE | ENT_XHTML, "UTF-8"));

Resulted in this output:

Array
(
    ["] => "
    [&] => &
    ['] => '
    [<] => &lt;
    [>] => &gt;
)
Array
(
    ["] => &quot;
    [&] => &amp;
    ['] => &#039;
    [<] => &lt;
    [>] => &gt;
    [ ] => &nbsp;
    // ...
    // ...
)

But I expected the specialchars table to be a subset of the entities table. The single quotes in the entities table is substituted using the decimal notation, while it uses the html5 named entity notation in the specialchars table.

PHP Version

PHP 5.4 to PHP 8.2

Operating System

mint/ubuntu 22.04

首先，在受支持的 PHP 构建上重现 issue 中的 get_html_translation_table() 调用，并将 HTML_SPECIALCHARS 和 HTML_ENTITIES 与 ENT_XHTML 进行比较。追踪这些 flags 的实现和现有测试；当 specialchars 表中的引号映射与 entities 表保持一致（包括单引号的表示形式）时，即可视为完成。