[m-rev.] for review: import instance declarations transitively

[Simon Taylor]

Estimated hours taken: 0.5
Branches: main

compiler/modules.m:
	Put instance declarations in the `.int2' files to avoid
	producing `superclass constraints not satisfied' errors
	for instance declarations for subclasses defined in the
	interface of importing modules.

	Without this change, all modules importing the module definining
	the instance for the subclass must also import the module
	defining the instance for the superclass.

tests/valid/Mmakefile:
tests/valid/transitive_instance.m:
	Test case.

Index: compiler/modules.m
===================================================================
RCS file: /home/mercury1/repository/mercury/compiler/modules.m,v
retrieving revision 1.239
diff -u -u -r1.239 modules.m
--- compiler/modules.m	30 Jun 2002 17:06:33 -0000	1.239
+++ compiler/modules.m	22 Jul 2002 07:48:05 -0000
@@ -5961,6 +5961,7 @@
 include_in_short_interface(inst_defn(_, _, _, _, _)).
 include_in_short_interface(mode_defn(_, _, _, _, _)).
 include_in_short_interface(module_defn(_, _)).
+include_in_short_interface(instance(_, _, _, _, _, _)).
 
 :- pred make_abstract_defn(item, short_interface_kind, item).
 :- mode make_abstract_defn(in, in, out) is semidet.
@@ -5984,6 +5985,8 @@
 		% types only for the `.int3' files.
 		ShortInterfaceKind = int3
 	).
+make_abstract_defn(instance(_, _, _, _, _, _) @ Item0, int2, Item) :-
+	make_abstract_instance(Item0, Item).
 make_abstract_defn(typeclass(A, B, C, _, E), _,
 		typeclass(A, B, C, abstract, E)).
 
Index: tests/valid/Mmakefile
===================================================================
RCS file: /home/mercury1/repository/tests/valid/Mmakefile,v
retrieving revision 1.108
diff -u -u -r1.108 Mmakefile
--- tests/valid/Mmakefile	21 Jul 2002 08:00:54 -0000	1.108
+++ tests/valid/Mmakefile	23 Jul 2002 05:30:27 -0000
@@ -162,6 +162,7 @@
 	switches.m \
 	tabled_io.m \
 	tabled_for_io.m \
+	transitive_instance.m \
 	tricky_assert2.m \
 	tricky_ite.m \
 	two_pragma_c_codes.m \
Index: tests/valid/transitive_instance.m
===================================================================
RCS file: tests/valid/transitive_instance.m
diff -N tests/valid/transitive_instance.m
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ tests/valid/transitive_instance.m	23 Jul 2002 05:29:47 -0000
@@ -0,0 +1,34 @@
+:- module transitive_instance.
+
+:- interface.
+
+:- type t.
+
+:- implementation.
+
+:- import_module transitive_instance__sub2.
+
+:- type t ---> some [T] c(T) => c2(T).
+
+:- module transitive_instance__sub1.
+
+	:- interface.
+
+	:- typeclass c1(T) where []. 
+
+	:- instance c1(int) where [].
+
+:- end_module transitive_instance__sub1.
+
+
+:- module transitive_instance__sub2.
+	
+	:- interface.
+
+	:- import_module transitive_instance__sub1.
+
+	:- typeclass c2(T) <= c1(T) where [].
+
+	:- instance c2(int) where [].
+
+:- end_module transitive_instance__sub2.
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