[m-rev.] for review: fix bug with any insts in inst_merge

[David Overton]

On Fri, Sep 14, 2001 at 02:50:53AM +1000, Fergus Henderson wrote:
> On 11-Sep-2001, David Overton <dmo at cs.mu.OZ.AU> wrote:
> > Fix a bug in inst_merge when merging a ground inst with a bound inst
> > containing 'any' insts.  Previously,
> > 
> > 	inst_merge(ground, bound(f(..., any, ...)))
> > 
> > would return a result of 'any' which is not as accurate as we would
> > like (e.g. this problem occurs often in Mercury code generated by the
> > HAL compiler).  To improve this, we pass the type of the variable
> > being merged to inst_merge and when this situation arises we expand
> > 'ground' to 'bound(<functors of type>)' and use this inst in the
> > merge.
> 
> That looks fine.
> 
> Just a few minor comments:
> 
> > Index: compiler/inst_util.m
> > @@ -1425,9 +1419,12 @@
> >  	),
> >  	merge_uniq(UniqA, UniqB, Uniq).
> >  inst_merge_3(abstract_inst(Name, ArgsA), abstract_inst(Name, ArgsB),
> > -		ModuleInfo0, abstract_inst(Name, Args), ModuleInfo) :-
> > -	inst_list_merge(ArgsA, ArgsB, ModuleInfo0, Args, ModuleInfo).
> > -inst_merge_3(not_reached, Inst, M, Inst, M).
> > +		_, ModuleInfo0, abstract_inst(Name, Args), ModuleInfo) :-
> > +	MaybeTypes = list__duplicate(list__length(ArgsA), no),
> > +		% We don't know the arguments types of an abstract inst.
> 
> The comment here should precede the code to which it applies,
> rather than following it.

Done

> 
> > Index: compiler/type_util.m
> ...
> > +		->
> > +			list__map(pred(T::in, yes(T)::out) is det, Types,
> > +				MaybeTypes)
> 
> I'd write that using the functional form:
> 
> 			MaybeTypes = list__map(func(T) = yes(T), Types)

Done

> 
> > +maybe_get_higher_order_arg_types(MaybeType, Arity, MaybeTypes) :-
> > +	(
> > +		MaybeType = yes(Type),
> > +		type_is_higher_order(Type, _, _, Types)
> > +	->
> > +		list__map(pred(T::in, yes(T)::out) is det, Types, MaybeTypes)
> > +	;
> > +		list__duplicate(Arity, no, MaybeTypes)
> 
> Likewise here.

Done


-- 
David Overton      Department of Computer Science & Software Engineering
PhD Student        The University of Melbourne, Victoria 3010, Australia
+61 3 8344 9159    http://www.cs.mu.oz.au/~dmo
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