[m-rev.] for review: check for type defn consistency when generating interface files

[Julien Fischer]

Hi Zoltan,

On Fri, 27 Sep 2019, Zoltan Somogyi wrote:

> There should be a new entry in notes/compiler_design.html
> for the new module, but I am wondering whether the new module,
> besides the new code now in it, should also contain the conversion
> code between the various kinds of interface files, since that code
> does not have much in common with the rest of prog_item.m.

The conversion code should *not* be in prog_item.m, that means exposing
the declarations for those conversion functions to many other places in
the compiler that do not need to know about them; whether it should be
in the new module added here is a separate question.  I suggest adding
them to a new module, e.g. convert_interface, rather than adding
them to the new module here.

> If people agree, I would need a new name for the new module,
> and would need to document that instead in compiler_design.html.
> (Including that move in this diff would have made the diff much
> harder to review.)
>
> I would like to build on this change tomorrow, so in the absence
> of both reviews and objections, I plan to commit it tomorrow
> around lunchtime.

I've had a look through the change and don't have any objections
to anything in it, so feel free to commit.

Julien.