Personally, I would find the use of parentheses quirky here, but square
brackets don't work because [[ and ]] are meant to be for attributes always.

Maybe if you had some really good motivating examples that show where you
need nested structured bindings frequently, I could be convinced, but
otherwise from me, it's a big

eh, not worth the trouble, and we can't have nice syntax for it


The example that you have provided seems to use an artificially long name
for the bindings rather than e.g. [key, val] in order to make the savings
seem more significant. Do you have some real-world examples?


On Mon, 21 Sept 2026 at 14:15, HHN via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> Currently structured bindings do not allow for nested bindings.
>
> std::map<Identifier, std::pair<Handle, Context>> map;
>
> // to get a copy of identifier, handle and info
> for (const auto &[identifierRef, handleWithContextRef] : map)
> {
> auto identifier = identifierRef;
> auto [handle, context] = handleWithContextRef;
> }
>
> // Suggested replacement
> for(auto [identifier, (handle, context)]: map)
> {
> }
>
> All sb-identifiers in the structured-binding-declaration will have the
> same reference qualifier.
>
> *Updated in the C++ grammar*
>
> sb-identifier :
> ...opt identifier attribute-specifier-seqopt
> ( sb-identifier-list ) // new production rule
>
> sb-identifier-list :
> sb-identifier
> sb-identifier-list , sb-identifier
>
> structured-binding-declaration :
> attribute-specifier-seqopt decl-specifier-seq ref-qualifieropt [
> sb-identifier-list ]
>
>
> I have attached an argument
> <https://gist.github.com/Johan511/3bbae06c683fd343a08aa6c50f1de0ed> that
> this won't cause any parsing ambiguities
>
> --
> Hari Hara Naveen
> --
> Std-Proposals mailing list
> Std-Proposals_at_[hidden]
> https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals
>