>
> typeset -g "${1-x}=$match[2]" "${2-y}=$match[1]"


> Doesn't work either. I guess there's no way to access variables
> by the same name in that parent scope or to unlocal a variable?


I just stumbled on the module zsh/param/private
<https://zsh.sourceforge.io/Doc/Release/Zsh-Modules.html#The-zsh_002fparam_002fprivate-Module>,
which makes it possible (but I won't claim that it's very practical):

assign() {
>     print -v "$1" "$2"
> }
>
> curpos() {
>     set -o localoptions -o extendedglob
>     # Initialize the return variables. Without this, print -v fails if
>     # the variable is the same as one of the private variables.
>     eval "${1-x}= ${2-y}="
>     zmodload zsh/param/private
>     local -P -a match mbegin mend
>     local -P answer
>     IFS= read -rsdR -t0.2 answer$'?\e[6n' &&
>         [[ $answer = (#b)$'\e['(<->)';'(<->) ]] &&
>         assign ${1-x} "$match[2]" &&
>         assign ${2-y} "$match[1]"
> }
>
> curpos answer match
> echo x=$answer y=$match
>

It's a bit strange that the initialization is needed. Private variables
don't hide global variables of the same name, nor prevent their assignment,
but prevent their initial declaration.

Philippe