The manual described the signature-change refusal as though it were the
design. It is not, and session.ml already said so at the refusal: a
signature change should make a new version, leave old callers on the old
one, and warn at the stale sites. plan.org calls it signature generations
and stale-caller warnings, and it is milestone 7's unfinished half.
The struct-layout rejection is the decided one and stays. Conflating them
made a placeholder look like a rule.
Joseph Ferano
3afce2aeac