[m-rev.] for review: separate out semantic checks for fact tables

[Julien Fischer]

On Thu, 10 Jun 2021, Zoltan Somogyi wrote:

> Separate semantic checks on fact table preds ...
> 
> from code generation for them.

...

> compiler/typecheck_errors.m:
>     If a predicate has a fact_table for it, then its clauses (actually,
>     foreign_procs) are supposed to be provided by the compiler;
>     the absence of user-supplied clauses is to be expected.
>     If, due to incompatility between the predicate's declarations

s/incompatility/incompatibility/

>     and the requirements of fact tables, the compiler cannot generate
>     those foreign_procs, do not generate an error message about
>     the absence of clauses, since such an error message would be misleading.
>     The problem *will* be reported by fact_table.m.

...

> diff --git a/compiler/fact_table.m b/compiler/fact_table.m
> index b73e43055..14a991412 100644
> --- a/compiler/fact_table.m
> +++ b/compiler/fact_table.m

...

> +
> +    % Initialise list of fact argument information. Input and output flags
> +    % are initialised to `no' and filled in correctly by
> +    % infer_determinism_pass_1.
> +    %
> +:- pred init_fact_arg_infos(pred_info::in, list(mer_type)::in,
> +    list(fact_arg_info)::out,
> +    list(error_spec)::in, list(error_spec)::out) is det.
> +
> +init_fact_arg_infos(_, [], [], !Specs).
> +init_fact_arg_infos(PredInfo, [Type | Types], [Info | Infos], !Specs) :-
> +    ( if
> +        Type = builtin_type(BuiltinType),
> +        (
> +            BuiltinType = builtin_type_int(int_type_int),
> +            FactArgTypePrime = fact_arg_type_int
> +        ;
> +            BuiltinType = builtin_type_float,
> +            FactArgTypePrime = fact_arg_type_float
> +        ;
> +            BuiltinType = builtin_type_string,
> +            FactArgTypePrime = fact_arg_type_string
> +        )
> +    then
> +        FactArgType = FactArgTypePrime
> +    else
> +        pred_info_get_typevarset(PredInfo, TVarSet),
> +        TypeStr = mercury_type_to_string(TVarSet, print_name_only, Type),
> +        pred_info_get_context(PredInfo, Context),
> +        Pieces = [words("Error: type"), quote(TypeStr),
> +            words("is not allows in fact tables."),

s/allows/allowed/

> +            words("The only types allowed in fact tables are"),
> +            quote("int"), suffix(","), quote("float"), suffix(","),
> +            words("and"), quote("string"), suffix("."), nl],
> +        add_error_context_and_pieces(Context, Pieces, !Specs),
> +        FactArgType = fact_arg_type_int % Dummy; won't be used.
> +    ),
> +    Info = fact_arg_info(FactArgType,
> +        is_not_input_for_any_mode, is_not_in_or_output_for_any_mode),
> +    init_fact_arg_infos(PredInfo, Types, Infos, !Specs).

The rest looks fine.

Julien.