[Caml-list] Warning for unused variables

[Aymeric Fromherz <aymeric.fromherz@ens.fr>]

Hi,

Using OCaml 4.02.3, I do not have a warning for unused variables when
only one of the variables in a pair is unused.
For instance, the code

let (a,b) = (0, 42) in b;;

raises no warning, while

let (a,b) = (0,42) in 1;; raises the following

Warning 26: unused variable b.
Warning 26: unused variable a.

I would have expected a warning in the first case since a is unused.

Warnings for single unused variables, such as let a = 42 in 1 are still
raised.

What is the reason for this? Is this behaviour intended? How are unused
variables determined?

Thanks in advance,
Aymeric Fromherz