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[exec.connect] wording needs to ensure that in connect(sndr, rcvr) that rcvr expression is only evaluated once #325
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Proposed resolution
Change [exec.connect] p6 as follows:
The expression connect(sndr, rcvr) is expression-equivalent to: - (6.1) new_sndr.connect(rcvr) if that expression is well-formed Mandates: The type of the expression above satisfies operation_state. - (6.2) Otherwise, connect-awaitable(new_sndr, rcvr) +except that `rcvr` is evaluated only once. + Mandates: sender<Sndr> && receiver<Rcvr> is true.
The current wording of
connect(sndr, rcvr)defines thenew_sndrexpression astransform_sender(decltype(get-domain-late(sndr, get_env(rcvr))){}, sndr, get_env(rcvr)).It then defines
connect(sndr, rcvr)as expression equivalent tonew_sndr.connect(rcvr).As currently worded, this requires evaluating the
rcvrexpression twice. Note that the first usage in thenew_sndrexpression is unevaluated, but the second usage inget_env(rcvr)is evaluated.I think we need to add an extra sentence at the end of this section saying "Where the expression
rcvris only evaluated once." or similar.