[typesanitizer]

> If you have any language where it is "semantially correct" to execute it with a simple interpetter, than all optimizations in that language are not semantically important by definition, right?

Technically, yes. :)

But I think this should perhaps be treated as a bug in how we define/design languages, rather than as an immutable truth.

- We already have time-based versioning for languages. - We also have "tiers" of support for different platforms in language implementations (e.g. rarer architectures might have Tier 2 or Tier 3 support where the debugging tooling might not quite work)

One idea would be to introduce "tiers" into a language's definition. A smaller implementation could implement the language at Tier 1 (perhaps this would even be within reach for a university course project). An industrial-strength implementation could implement the language at Tier 3.

(Yes, this would also introduce more complications, such as making sure that the dynamic semantics at different tiers are equivalent. At that point, it becomes a matter of tradeoffs -- does introducing tiers help reduce complexity overall?)