A serious bug has been discovered last week in OCaml 4.11.0:
explicit polymorphic annotations are checked too permissively.
Some incorrect programs (possibly segfaulting) are accepted
by the compiler in 4.11.0.
Programs accepted by OCaml 4.10 are unchanged.
We are thus releasing OCaml 4.11.1 as an early bugfix version.
You are advised to upgrade to this new version if you were
using OCaml 4.11.0.
It is (or soon will be) available as a set of OPAM switches with
opam switch create 4.11.1
and as a source download here:
This bug was introduced when making polymorphic recursion
easier to use. We are working on making the typechecker
more robust and more exhaustively tested to avoid such
issues in the future.