diff: simplify.m bug

[Simon TAYLOR]

Hi Fergus,

Could you please review this.

Simon.


Estimated hours taken: 0.5

compiler/simplify.m
	Fix a bug in simplify.m where deconstructions were being
	propagated into lambda expressions, but the non-locals of the 
	lambda expressions were not being updated.

tests/valid/lambda_struct_bug.m
	Regression test.


Index: simplify.m
===================================================================
RCS file: /home/staff/zs/imp/mercury/compiler/simplify.m,v
retrieving revision 1.33
diff -u -r1.33 simplify.m
--- simplify.m	1997/05/21 02:13:49	1.33
+++ simplify.m	1997/06/21 13:17:00
@@ -439,15 +439,23 @@
 		RT0 = lambda_goal(PredOrFunc, Vars, Modes, LambdaDeclaredDet,
 			LambdaGoal0)
 	->
-		simplify_info_get_common_info(Info0, Common),
+		simplify_info_get_common_info(Info0, Common0),
 		simplify_info_get_module_info(Info0, ModuleInfo),
 		simplify_info_get_instmap(Info0, InstMap0),
 		instmap__pre_lambda_update(ModuleInfo, Vars, Modes,
 			InstMap0, InstMap1),
 		simplify_info_set_instmap(Info0, InstMap1, Info1),
-		simplify__goal(LambdaGoal0, LambdaGoal, Info1, Info2),
-		simplify_info_set_common_info(Info2, Common, Info3),
-		simplify_info_set_instmap(Info3, InstMap0, Info),
+
+		% Don't attempt to pass structs into lambda_goals,
+		% since that could change the curried non-locals of the 
+		% lambda_goal, and that would be difficult to fix up.
+		common_info_init(Common1),
+		simplify_info_set_common_info(Info1, Common1, Info2),
+
+		% Don't attempt to pass structs out of lambda_goals.
+		simplify__goal(LambdaGoal0, LambdaGoal, Info2, Info3),
+		simplify_info_set_common_info(Info3, Common0, Info4),
+		simplify_info_set_instmap(Info4, InstMap0, Info),
 		RT = lambda_goal(PredOrFunc, Vars, Modes, LambdaDeclaredDet,
 			LambdaGoal),
 		Goal = unify(LT0, RT, M, U0, C),

Index: Mmake
===================================================================
RCS file: /home/staff/zs/imp/tests/valid/Mmake,v
retrieving revision 1.39
diff -u -r1.39 Mmake
--- Mmake	1997/06/03 06:23:07	1.39
+++ Mmake	1997/06/25 07:53:46
@@ -34,6 +34,7 @@
 	lambda_inference.m\
 	lambda_instmap_bug.m \
 	lambda_quant.m \
+	lambda_struct_bug.m \
 	lambda_switch.m \
 	lambda_type.m \
 	loop.m \


% This is a regression test for a bug in simplify/common.m where
% the pos(X, Y) deconstruction in the head of adj/4 was being propagated
% into the body of the lambda expression, but the non-locals of
% the lambda expression were not being updated.
:- module lambda_struct_bug.

:- interface.

:- import_module list, std_util, set.

:- type pos
	--->	pos(int, int).

:- type adj
	--->	adj(pos, pos).

:- type maze	==	set(pair(pos, pos)).

:- pred adj(pos, list(adj)).
:- mode adj(in, out) is det.

:- implementation.

:- import_module int, require.

adj(pos(X, Y), Adjs) :-
	Pred = lambda([Adj::out] is nondet, (
			(
				X1 is X - 1,
				Adj = adj(pos(X1, Y), pos(X, Y))
			;
				X1 is X + 1,
				Adj = adj(pos(X1, Y), pos(X, Y))
			;
				Y1 is Y + 1,
				Adj = adj(pos(X, Y1), pos(X, Y))
			;
				Y1 is Y - 1,
				Adj = adj(pos(X, Y1), pos(X, Y))
			),
			Adj = adj(pos(A, B), _),
			A >= 0, A =< 10, % XXX
			B >= 0, B =< 10 % XXX
	)),
	solutions(Pred, Adjs).