[m-rev.] for review: pragma status checks

[Julien Fischer]

On Sat, 24 Sep 2022, Zoltan Somogyi wrote:

> Fix the handling of status in add_pragma.m.
> 
> compiler/add_pragma.m:
>     The status checks in this module used to check for only one
>     of the four possible combinations of <is pragma exported, is the
>     pred the pragma is for expored>, even though we may want to generate
>     errors or warnings in three of those combinations. Fix this.
>
>     If an ambiguous pragma applies to more than one predicate, handle
>     the status checks of each separately.
>
>     When adding fact table pragmas to the HLDS, replace several lines
>     of code that reuse an existing largish predicate with the single line
>     of code from that predicate that we actually need.
>
>     Stop representing the statuses of pragmas using the pred_status type,
>     since the item_mercury_status that all items come with is adequate
>     for all our needs, and is impossible to confuse with the status
>     of the pred_info they refer to.

...


> diff --git a/compiler/add_pragma.m b/compiler/add_pragma.m
> index 624462f33..6ab9b71d1 100644
> --- a/compiler/add_pragma.m
> +++ b/compiler/add_pragma.m
> @@ -2135,34 +2080,128 @@ maybe_warn_about_pfumm_unknown(ModuleInfo, PragmaName, PFUMM, SymName, Context,

...

> +                PragmaExported = no,
> +                % Case 3: ok for impl pragmas, warning for decl pragmas.
> +                (
> +                    StatusClass = psc_decl,
> +                    PredNamePieces = describe_one_pred_info_name(
> +                        should_not_module_qualify, PredInfo),
> +                    Pieces = [words("Warning: since the")] ++
> +                        PredNamePieces ++ [words("is exported, the"),
> +                        pragma_decl(PragmaName), words("declaration for it"),
> +                        words("should also be exported."), nl],
> +                    Spec = simplest_spec($pred, severity_warning,
> +                        phase_parse_tree_to_hlds, Context, Pieces),
> +                    !:Specs = [Spec | !.Specs]
> +                ;
> +                    StatusClass = psc_impl
> +                )
> +            ;
> +                PragmaExported = yes,
> +                % Case 4: ok for decl pragmas, error for impl pragmas.
> +                (
> +                    StatusClass = psc_decl
> +                ;
> +                    StatusClass = psc_impl,
> +                    % NOTE We never generate this error message, because
> +                    % the parser generate an error message for any impl

s/generate/generates/

> +                    % pragmas in interfaces, and declines to add them
> +                    % to the parse tree. Indeed, parse_tree_module_src type,

*the* parse_tree_module_src type

> +                    % which represents the parse trees of source modules,
> +                    % cannot represent impl pragmas in interface sections.
> +                    Pieces = [words("Error: a"),
> +                        pragma_decl(PragmaName), words("declaration"),
> +                        words("may not be exported, even if"),
> +                        words("the predicate or function it refers to"),
> +                        words("is exported."), nl],
> +                    Spec = simplest_spec($pred, severity_error,
> +                        phase_parse_tree_to_hlds, Context, Pieces),
> +                    !:Specs = [Spec | !.Specs]
> +                )
> +            )
> +        )

That looks fine otherwise.

Julien.