[m-rev.] diff: dotnet: fix bug with unify/2

[Fergus Henderson]

Estimated hours taken: 3
Branches: main

compiler/mlds_to_il.m:
	Fix a bug that broke unify/2 in IL grades:
	handle semidet `:- external' routines.

	XXX `:- external' functions are still not supported.

Index: mlds_to_il.m
===================================================================
RCS file: /home/mercury1/repository/mercury/compiler/mlds_to_il.m,v
retrieving revision 1.32
diff -u -d -u -r1.32 mlds_to_il.m
--- mlds_to_il.m	2001/06/14 22:36:16	1.32
+++ mlds_to_il.m	2001/06/18 09:16:39
@@ -316,7 +316,7 @@
 
 			% Generate the code of the statement.
 		( { MaybeStatement = yes(Statement) } -> 
-			statement_to_il(Statement, InstrsTree0)
+			statement_to_il(Statement, InstrsTree1)
 		;
 				% If there is no function body,
 				% generate forwarding code instead.
@@ -325,7 +325,21 @@
 				InstrsTree0),
 				% The code might reference locals...
 			il_info_add_locals(["succeeded" - 
-				mlds__native_bool_type])
+				mlds__native_bool_type]),
+			( { Returns = [_] } ->
+				% XXX Bug!
+				% We assume that if there is a return value,
+				% then it must be a semidet procedure, so
+				% we return `succeeded'.
+				% This is wrong for functions!
+				{ InstrsTree1 = tree__list([
+					InstrsTree0,
+					instr_node(ldloc(name("succeeded"))),
+					instr_node(ret)
+				]) }
+			;
+				{ InstrsTree1 = InstrsTree0 }
+			)
 		),
 
 			% If this is main, add the entrypoint, set a
@@ -357,7 +371,7 @@
 		{ InstrsTree = tree__list([
 			context_node(Context),
 			instr_node(start_block(scope(Locals), BlockId)),
-			InstrsTree0, 
+			InstrsTree1, 
 			MaybeRet,
 			instr_node(end_block(scope(Locals), BlockId))
 			])
-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  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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