Re: [Caml-list] Record field disambiguation in 4.01

[Alain Frisch <alain@frisch.fr>]

On 03/10/2013 12:39 AM, Yaron Minsky wrote:
> Also, I'm wondering if anyone has thoughts as to how much code this
> change will break?  The answer might be "quite a lot", and it might
> nonetheless be worth it.  But I'm curious what people's thoughts are.

As Jacques said, this is only a warning, which is turned off by default. 
  I expect that all the "unused stuff" warnings also broke most code 
bases around which are compiled with "-w +A -warn-error A".  I'm sure 
you are not suggesting that new warnings should never be triggered on 
code which used to be well-typed by a previous version of the compiler...

The warning tells you something useful: with that record type 
declaration, the reference to field "y" becomes ambiguous, which means 
in particular that (i) your code might become fragile w.r.t. reordering 
of type declarations, (ii) the code might become harder to read (the 
reader might expect that field "y" is typically related to a different 
record type in your code base).  Of course, a more explicit warning 
message, as you suggest, would be even better.

During the discussion on type-based disambiguation, Mark Shinwell 
commented that most record types in JS code base are defined in nested 
modules (and often exposed only through builder functions) to avoid 
label clashes.  Is your example an instance where this is not the case?


Alain