Description

The Html::_namespaceInputs() function can't take numbers as a namespace, because they break the regex replacement pattern. Numbers get concatenated with the capture reference, which changes the reference number.

Problem: '$1' . $namespace . '[$3]$4$2' turns into '$13[$3]$4$2' when $namespace = '3'. The reference $1 changed to $13.

This twig code

{{ '<input name="test">'|namespace('3')|raw }}

currently generates this html

<input [test]">

More info from php.net/manual/en/function.preg-replace

When working with a replacement pattern where a backreference is immediately followed by another number (i.e.: placing a literal number immediately after a matched pattern), you cannot use the familiar \1 notation for your backreference. \11, for example, would confuse preg_replace() since it does not know whether you want the \1 backreference followed by a literal 1, or the \11 backreference followed by nothing. In this case the solution is to use ${1}1. This creates an isolated $1 backreference, leaving the 1 as a literal.

Related issues

-/-