module type of in OCaml 5.0: Resolving Nested Module Signature Mismatches

Goal

We want to understand how the semantics of module type of change when applied to a nested module in OCaml 5.0 compared to 4.14, and how this affects type inference and compiler diagnostics during migration.

Context

In 5.0 the compiler warns that module type of is deprecated, but the warning text differs between bytecode and native compilers. The documentation states that the construct should preserve the original module type, yet tests show that private types inside nested modules alter the inferred signature. This discrepancy is not yet resolved in the issue tracker.

Uncertainty

It is unclear whether the variation is a bug, a documented change, or a compiler‑flag‑dependent behavior. The current release notes do not mention a change to the semantics, and the implementation source shows an internal inconsistency. Future releases may adjust the rule.

Questions

1. Does OCaml 5.0 intentionally change the inferred signature of module type of when it targets a nested module containing private types, or is this an implementation quirk?
2. What impact does the -strict-sequence flag have on the diagnostics produced for nested module type of constructs in 5.0?
3. Is there an upcoming deprecation or replacement strategy for module type of that developers should adopt to avoid migration surprises?