[m-rev.] help needed: fix rtti bug

[Fergus Henderson]

On 19-Dec-2003, Peter Ross <pro at missioncriticalit.com> wrote:
> Any hints on how to work out the arity of a variable arity type_ctor
> on the IL backend.

The arity is stored in the first field of the type_info;
i.e., since the type_info has type Object[], the arity
will be "(int) type_info[0]".

> +++ library/rtti_implementation.m	19 Dec 2003 10:58:51 -0000
> @@ -919,7 +919,15 @@
>  type_ctor_name_and_arity(TypeCtorInfo, ModuleName, Name, Arity) :-
>  	ModuleName = type_ctor_module_name(TypeCtorInfo),
>  	Name = type_ctor_name(TypeCtorInfo),
> -	Arity = type_ctor_arity(TypeCtorInfo).
> +	( type_ctor_is_variable_arity(TypeCtorInfo) ->
> +		Arity = type_ctor_va_arity(TypeCtorInfo)
> +	;
> +		Arity = type_ctor_arity(TypeCtorInfo)
> +	).

The interface to this predicate is wrong.  Given a type_ctor, there is
no way to compute the arity. You need the type_info.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.
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