Missing warnings with OCaml 4.02.1 on Emacs

[dhekir]

I'm having some issues similar to #254, but related to other warnings.

Using OCaml 4.02.1, I tried with merlin 2.0.0 and also with the master branch, but could not get some warnings to be emitted by merlin.

Consider the following code:

let f x y = x

let f (t : Genlex.token) = match t with | Ident _ -> 1 | _ -> 0

When running ocamlc -w +a, I get:

File "test.ml", line 3, characters 42-47:
Warning 40: Ident was selected from type Genlex.token.
It is not visible in the current scope, and will not
be selected if the type becomes unknown.
File "test.ml", line 3, characters 42-47:
Warning 42: this use of Ident required disambiguation.
File "test.ml", line 3, characters 27-63:
Warning 4: this pattern-matching is fragile.
It will remain exhaustive when constructors are added to type Genlex.token.
File "test.ml", line 3, characters 27-63:
Warning 4: this pattern-matching is fragile.
It will remain exhaustive when constructors are added to type Genlex.token.
File "test.ml", line 1, characters 4-5:
Warning 32: unused value f.
File "test.ml", line 1, characters 8-9:
Warning 27: unused variable y.

Then I ran merlin inside Emacs on a directory containing the following .merlin:

FLG -w +a

The only warning I get (twice) is:

Warning 4: this pattern-matching is fragile.
It will remain exhaustive when constructors are added to type Genlex.token.

Warnings 27, 32, 40 and 42 were not printed.

Did I do something wrong? I even tried hardcoding flags "-w" "+a" directly on emacs/merlin.el, but to no avail.

[let-def]

Those warnings are checked in a later pass in usual ocaml compiler, which is not really implemented in merlin pipeline.

This can be improved, but require some fundamental reorganization.

[dhekir]

Oh, I see, I suspected it might be more complex than I expected. I mostly wanted to make sure I had not misconfigured things in my side.
Thank you for the information. Ocamlmerlin is already extremely useful as it is already. I'll try and think of some emacs-lisp code to help me get the warnings.