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4524. Wrong deduced return type in [exec.schedule.from]

Section: 33.9.12.7 [exec.schedule.from] Status: New Submitter: Brian Bi Opened: 2026-01-20 Last modified: 2026-02-18

Priority: Not Prioritized

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Discussion:

I think there's a problem in the definition of receiver-type in 33.9.12.7 [exec.schedule.from] p10:

When state-type is instantiated, operation_t must be determined. To determine operation_t, we need to know the environment type for receiver_t, which requires instantiating the definition of receiver_t::get_env because of the deduced return type. That definition requires state-type to be already complete because it uses state->rcvr, so we have a circular dependency.

The return type should probably be written out explicitly as FWD-ENV-T(env_of_t<Rcvr>) or something like that (except that it seems like Rcvr is already "out of scope" here, so I don't know how to word it exactly).

Proposed resolution: