[m-rev.] for review: do occurs checks on the parse tree

[Peter Wang]

On Wed, 15 Apr 2020 02:57:04 +1000 (AEST), "Zoltan Somogyi" <zoltan.somogyi at runbox.com> wrote:
> 
> The attached diff implements this. For post commit review by anyone.

> diff --git a/tests/warnings/occurs.m b/tests/warnings/occurs.m
> index b98ee2475..80bb98794 100644
> --- a/tests/warnings/occurs.m
> +++ b/tests/warnings/occurs.m
> @@ -10,24 +10,64 @@
...
>      ( if
>          disable_warning [suspected_occurs_check_failure] (
> +            % We should not get a warning for this occurs check
> +            % violatiom because the warnings has been disabled.
>              A = [_A2, _A3, _A4 | A]
>          )
>      then
> -        Y = 1
> +        Z = 1
>      else
> -        Y = 2
> +        Z = 2
> +    ),
> +
> +    Program = program(0),
> +    Interpretation = set.make_singleton_set("xyzzy"),
> +    % We should not get a warning for this occurs check violatiom
> +    % because the function symbol involved is not a *data* constructor.
> +    ( if Interpretation = tp(Program, Interpretation) then
> +        MaybeFixpoint = "have reached fixpoint"
> +    else
> +        MaybeFixpoint = "have not reached fixpoint"
>      ).

I've fixed the couple of spelling mistakes in this file directly.

The rest looks fine.

Peter