diff: scripts/Mmake.rules fix

[Fergus Henderson]

Hi,

You may have noticed mmake behaving a little wierdly over the last month
or two, since jal installed a new version of GNU Make on murlibobo.
This should fix the problem (albeit at a cost of a small slowdown in
mmake times).

scripts/Mmake.rules:
	Work around a new (mis-)feature present in GNU Make 3.74
	but not in 3.71: recent versions will not update the timestamp
	of a target if the commands for that target are just whitespace.
	Instead, we need to use an explicit sh `:' command.

Index: Mmake.rules
===================================================================
RCS file: /home/staff/zs/imp/mercury/scripts/Mmake.rules,v
retrieving revision 1.40
diff -u -r1.40 Mmake.rules
--- Mmake.rules	1997/02/07 13:21:01	1.40
+++ Mmake.rules	1997/05/23 00:31:39
@@ -58,20 +58,23 @@
 .m.optdate:
 	$(MCOI) $(MCOIFLAGS) $<
 
-# do not remove the whitespace in the following four rules!
+# Be very careful about changing the following rules.
+# The `@:' is a silent do-nothing command.
+# It is used to force GNU Make to recheck the timestamp
+# on the target file.  (It is a pity that GNU Make doesn't
+# have a way of handling these sorts of rules in a nicer manner.)
 
 .date.int:
-	
+	@:
 
 .date.int2:
-	
+	@:
 
 .date3.int3:
-	
+	@:
 
 .optdate.opt:
-	
-
+	@:
 
 .m.garb:
 	$(MCG) -s $(GRADE) --garbage-collection accurate $(MCGFLAGS) $<

-- 
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.