[m-rev.] for review: fix Java compilation of table_builtin.m

[Fergus Henderson]

For review by Zoltan.

Estimated hours taken: 0.5
Branches: main

library/table_builtin.m:
	Use univ rather than unsafe_type_cast, because using
	unsafe_type_cast with an invalid type can result in compilation
	errors in Java grades.

Workspace: /home/jupiter/fjh/ws-jupiter/mercury
Index: library/table_builtin.m
===================================================================
RCS file: /home/mercury1/repository/mercury/library/table_builtin.m,v
retrieving revision 1.40
diff -u -d -r1.40 table_builtin.m
--- library/table_builtin.m	2 Aug 2004 01:40:03 -0000	1.40
+++ library/table_builtin.m	2 Aug 2004 06:58:34 -0000
@@ -1043,17 +1043,17 @@
 table_mmos_setup_consumer(_, _, Consumer) :-
 	impure private_builtin__imp,
 	% Required only to avoid warnings; never executed.
-	private_builtin__unsafe_type_cast(0, Consumer).
+	pretend_to_generate_value(Consumer).
 
 table_mmos_get_answer_table(_, TrieNode) :-
 	semipure private_builtin__semip,
 	% Required only to avoid warnings; never executed.
-	private_builtin__unsafe_type_cast(0, TrieNode).
+	pretend_to_generate_value(TrieNode).
 
 table_mmos_create_answer_block(_, _, AnswerBlock) :-
 	impure private_builtin__imp,
 	% Required only to avoid warnings; never executed.
-	private_builtin__unsafe_type_cast(0, AnswerBlock).
+	pretend_to_generate_value(AnswerBlock).
 
 table_mmos_return_answer(_, _) :-
 	impure private_builtin__imp.
@@ -1061,6 +1061,12 @@
 table_mmos_completion(_) :-
 	impure private_builtin__imp.
 
+	% Required only to avoid warnings; never executed.
+:- pred pretend_to_generate_value(T::out) is det.
+pretend_to_generate_value(Bogus) :-
+	% The following code will throw an exception if executed.
+	det_univ_to_type(univ(0), Bogus).
+
 %-----------------------------------------------------------------------------%
 
 :- interface.
@@ -1183,7 +1189,7 @@
 %-----------------------------------------------------------------------------%
 
 :- implementation.
-:- import_module require.
+:- import_module require, std_util.
 
 :- pragma foreign_decl("C", "
 

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