[m-rev.] for review: structured MLDS var names

[Julien Fischer]

Hi Zoltan,

On Mon, 24 Apr 2017, Zoltan Somogyi wrote:

>
>
> On Sun, 23 Apr 2017 22:31:02 +1000 (AEST), Julien Fischer <jfischer at opturion.com> wrote:
>>>     This design has a couple of minor problems. The first is that there is
>>>     no place in the compiler where all the variable names are visible at once,
>>>     and without such a place, we cannot be sure that two names constructed
>>>     for different purposes don't accidentally end up with the same name.
>>>     The probability of such a clash used to be astronomically small
>>
>> See bug #92 <https://bugs.mercurylang.org/view.php?id=92>.
>
> I have tried to reproduce that problem with my installed compiler
> (which does not have this diff), but failed.

That's not surprising, IIRC I couldn't reproduce it with the rotd
from a few weeks after I found it.

> I know it was a very long time ago, but do you remember anything about
> the context of the duplication? In other words, what did the generated
> code use the nested occurrence of HeadVar__1_1 for?

Sorry, I've long since forgotten the details, and that code has long
since been eliminated from the program (the Zinc compiler) that it was a
part of.

Julien.