diff: Fix bug in modechecking of non-local lambda vars

[Fergus Henderson]

On 06-Feb-1998, Andrew Bromage <bromage at cs.mu.OZ.AU> wrote:
> compiler/inst_util.m:
> 	Export make_shared_inst_list/4.

The log message should say why (e.g. "for use by blah.m").

> +report_mode_error_non_local_lambda_var(ModeInfo, Var, VarInst) -->
> +	{ mode_info_get_context(ModeInfo, Context) },
> +	{ mode_info_get_varset(ModeInfo, VarSet) },
> +	{ mode_info_get_instvarset(ModeInfo, InstVarSet) },
> +	mode_info_write_context(ModeInfo),
> +	prog_out__write_context(Context),
> +	io__write_string("  mode error: variable `"),
> +	mercury_output_var(Var, VarSet, no),
> +	io__write_string("' has instantiatedness `"),
> +	output_inst(VarInst, InstVarSet),
> +	io__write_string("',\n"),
> +	prog_out__write_context(Context),
> +	io__write_string("  expected instantiatedness for non-local variables of  lambda goals\n"),
> +	io__write_string("  is `ground'.\n").

You need to wrap the long line onto the next line,
and you're missing a call to prog_out__write_context.

> --- modecheck_unify.m	1998/01/30 06:12:52	1.27
> +++ modecheck_unify.m	1998/02/06 00:16:48
> @@ -334,6 +334,7 @@
>  	% First modecheck the lambda goal itself:
>  	%
>  	% initialize the initial insts of the lambda variables,
> +	% check that the non-local vars are ground,
>  	% lock the non-local vars,
>  	% mark the non-clobbered lambda variables as live,
>  	% modecheck the goal,

I think

	% mark the non-local vars as shared,

should go in that list before "lock the non-local vars".

> +		% XXX This test is too conservative.
> +		%
> +		%     We should allow non-local variables to be non-ground
> +		%     if they are dead after this unification.  In addition,

Why only if they are dead after this unification?
Why not always?

> Index: tests/invalid/bind_var_errors.err_exp
> ===================================================================
> bind_var_errors.m:033: In clause for `bind_var_in_negation':
> bind_var_errors.m:033:   scope error: attempt to bind a variable inside a negation.
> bind_var_errors.m:033:   Variable `X' has instantiatedness `free',
> bind_var_errors.m:033:   expected instantiatedness was `unique(42)'.
> bind_var_errors.m:039: In clause for `bind_var_in_ite_cond(in)':
> bind_var_errors.m:039:   scope error: attempt to bind a non-local variable inside the
> bind_var_errors.m:039:   condition of an if-then-else.

Hmm, it would better to wrap "inside the" onto the next line.

> bind_var_errors.m:048: In clause for `bind_var_in_lambda':
> bind_var_errors.m:048:   in argument 1 of call to predicate `call/1':
> bind_var_errors.m:048:   mode error: variable `Y' has instantiatedness `free',
> bind_var_errors.m:048:   expected instantiatedness for non-local variables of  lambda goals
>   is `ground'.

Wrap that line from "of lambda goals".

Otherwise, that looks good.  But can I please see
another diff before you commit that?  Thanks.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>   |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>   |  of excellence is a lethal habit"
PGP: finger fjh at 128.250.37.3         |     -- the last words of T. S. Garp.