for review: another existential types & .int files bug fix

[Fergus Henderson]

DJ, can you please review this one?

compiler/mercury_to_mercury.m:
	Fix yet another bug with incorrect parenthesization of
	pred declarations involving existential types:
	parentheses are needed if there are any existentially
	typed variables _or_ if there are any existential constraints.
	(The previous code used the first condition for the `('
	and the second condition for the `)', resulting in unmatched
	parentheses in the cases where these two conditions did
	not agree.)

Index: compiler/mercury_to_mercury.m
===================================================================
RCS file: /home/mercury1/repository/mercury/compiler/mercury_to_mercury.m,v
retrieving revision 1.143
diff -u -r1.143 mercury_to_mercury.m
--- mercury_to_mercury.m	1998/08/19 06:51:12	1.143
+++ mercury_to_mercury.m	1998/09/03 08:58:33
@@ -1292,7 +1292,7 @@
 		Purity, ClassContext, _Context, StartString, Separator) -->
 	io__write_string(StartString),
 	mercury_output_quantifier(VarSet, ExistQVars),
-	( { ExistQVars = [] } -> 
+	( { ExistQVars = [], ClassContext = context(_, []) } -> 
 		[] 
 	; 
 		io__write_string("(")
@@ -1307,10 +1307,10 @@
 		mercury_output_term(Type, VarSet, no),
 		mercury_output_remaining_terms(Rest, VarSet, no),
 		io__write_string(")"),
-		mercury_output_class_context(ClassContext, VarSet)
+		mercury_output_class_context(ClassContext, ExistQVars, VarSet)
 	;
 		mercury_output_bracketed_sym_name(PredName),
-		mercury_output_class_context(ClassContext, VarSet),
+		mercury_output_class_context(ClassContext, ExistQVars, VarSet),
 		mercury_output_det_annotation(MaybeDet)
 	),
 
@@ -1385,7 +1385,7 @@
 		Separator) -->
 	io__write_string(StartString),
 	mercury_output_quantifier(VarSet, ExistQVars),
-	( { ExistQVars = [] } -> 
+	( { ExistQVars = [], ClassContext = context(_, []) } -> 
 		[] 
 	; 
 		io__write_string("(")
@@ -1405,7 +1405,7 @@
 	),
 	io__write_string(" = "),
 	mercury_output_term(RetType, VarSet, no),
-	mercury_output_class_context(ClassContext, VarSet),
+	mercury_output_class_context(ClassContext, ExistQVars, VarSet),
 	mercury_output_det_annotation(MaybeDet),
 	io__write_string(Separator).
 
@@ -1422,14 +1422,14 @@
 
 %-----------------------------------------------------------------------------%
 
-:- pred mercury_output_class_context(class_constraints, varset, 
+:- pred mercury_output_class_context(class_constraints, existq_tvars, varset, 
 	io__state, io__state).
-:- mode mercury_output_class_context(in, in, di, uo) is det.
+:- mode mercury_output_class_context(in, in, in, di, uo) is det.
 
-mercury_output_class_context(ClassContext, VarSet) -->
+mercury_output_class_context(ClassContext, ExistQVars, VarSet) -->
 	{ ClassContext = constraints(UnivCs, ExistCs) },
 	mercury_output_class_constraint_list(ExistCs, VarSet, "&"),
-	( { ExistCs = [] } -> 
+	( { ExistQVars = [], ExistCs = [] } -> 
 		[] 
 	; 
 		io__write_string(")")

-- 
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.