<https://github.com/nim-lang/Nim/pull/21066> changed the definition (and implementation) of what a "strict function" is once again. The definition was changed to "stores to locations that involve a ptr/ref indirection are forbidden". As you can see in this pull request this makes the language less expressive and requires more `.cast(noSideEffect)` overrides but in practice the number of required changes was quite low.
The advantage is that rule is much easier to teach and reason about. Reporting an error only has a single line information. Complexities like "X is the statement that potentially connects Y to a graph G that is connected to an immutable parameter P and Y is mutated here" are gone. Another benefit is this new language rule does not depend on alias analysis so that generic code is not affected. No more "my generic func works with int but not with ref T". It's now so simple that I think we can enable strict funcs in upcoming Nim versions and eventually reap the benefits for Nim's optimizer. But as usual, the optimizer can also compute the same property on its own and not bother Nim programmers.
