Proposed resolution:

This wording is relative to N5001.

1. Modify [exec.let] as indicated:

   -13- Let `sndr` and `env` be subexpressions, and let `Sndr` be `decltype((sndr))`. If sender-for<Sndr, decayed-typeof<let-cpo>> is false, then the expression let-cpo.transform_env(sndr, env) is ill-formed. Otherwise, it is equal to JOIN-ENV(let-env(sndr), FWD-ENV(env)).

     auto& [_, _, child] = sndr;
     return JOIN-ENV(let-env(child), FWD-ENV(env));
   

[ Hagenberg 2025-02-11; move to Ready ]

[ 2025-02-07; Reflector poll ]

Set priority to 1 after reflector poll.

"We seem to be missing a guarantee that `auto [_,_,child] = sndr;` works. We guarantee that it can be used in a structured binding, but not that it must work with a size of three."

Imported from cplusplus/sender-receiver #319.

[exec.let] para 13 reads:

13. Let `sndr` and `env` be subexpressions, and let `Sndr` be `decltype((sndr))`. If sender-for<Sndr, decayed-typeof<let-cpo>> is false, then the expression let-cpo.transform_env(sndr, env) is ill-formed. Otherwise, it is equal to JOIN-ENV(let-env(sndr), FWD-ENV(env)).