https://issues.dlang.org/show_bug.cgi?id=23175
--- Comment #4 from Paul Backus <[email protected]> --- My summary the historical information above: * Except for a few months in 2018, `in` has consistently been documented as `const scope` since 2013. * Until `-preview=in`, the compiler has consistently treated `in` as `const`. * There has been considerable confusion over whether the spec or the compiler's behavior should be treated as authoritative w.r.t. the meaning of `in`. In light of this information, I am inclined to agree with Jonathan M Davis's comment from issue 17928: > If we want in to mean scope const instead of just const, then we're going > to need a means of migrating to that without immediately breaking code --
