in reply to Re^7: Regexp not capturing in named subrules
in thread Regexp not capturing in named subrules

Oh, hey. I didn't find that earlier because it seems to be misfiled under the (?(condition)yes-pattern|no-pattern) section but it goes on to answer my original question

From perlre:

/(?<NAME>(?&NAME_PAT)) (?(DEFINE) (?<NAME_PAT>....) )/x

Note that capture buffers matched inside of recursion are not accessible after the recursion returns, so the extra layer of capturing buffers is necessary. Thus $+{NAME_PAT} would not be defined even though $+{NAME} would be.