I just upgraded tls and got a spurious "make inconsistent assumptions over interface Tls" error. It goes away after dune clean.

To reproduce, create these files:

(library (name lib) (modules lib) (libraries tls))
(executable (name app) (modules app) (libraries lib))

(* app.ml *)
Lib.main ()

(* lib.ml *)
let main () = ()
let _ = Tls.Engine.server

(* lib.mli *)
val main : unit -> unit

And run the following steps:

• opam install --yes tls=0.9.3
• dune build app.exe
• opam install --yes tls=0.10.1
• dune build app.exe

Tested on dune 1.7.3.