When porting Mercury to a BSDI BSD/386 1.1 system,
I had problems with `ar' not handling long filenames. 
(The error message was "ar: libmercury.a: invalid file type".) 
If you get a similar error, try the following patch.

--- library/Mmakefile	Sat Jul 15 14:54:49 1995
+++ /home/mulga/pgrad/fjh/mercury/src/mercury-0.3/library/Mmakefile	Mon Sep  4 04:13:18 1995
@@ -109,7 +109,10 @@
 libmercury : libmercury.a libmercury.$(SO) library.init
 
 libmercury.a : $(library.os)
-	ar cr libmercury.a $(library.os)
+	# ar cr libmercury.a $(library.os)
+	-ln -s mercury_builtin.o m_builtin.o
+	ar cr libmercury.a \
+		`echo $(library.os) | sed 's/mercury_builtin/m_builtin/'`
 	$(RANLIB) libmercury.a
 
 libmercury.so : $(library.pic_os)
--- boehm_gc/Makefile	Sun Apr  2 19:11:25 1995
+++ /home/mulga/pgrad/fjh/mercury/src/mercury-0.3/boehm_gc/Makefile	Sun Jan  1 01:01:29 1995
@@ -138,7 +138,9 @@
 	rm -f on_sparc_sunos5
 	./if_mach SPARC SUNOS5 touch on_sparc_sunos5
 	./if_mach SPARC SUNOS5 $(AR) rus gc.a $(OBJS) dyn_load.o
-	./if_not_there on_sparc_sunos5 $(AR) ru gc.a $(OBJS) dyn_load.o
+	-ln -s solaris_threads.o s_threads.o
+	./if_not_there on_sparc_sunos5 $(AR) ru gc.a \
+		`echo $(OBJS) | sed 's/solaris_threads/s_threads/'` dyn_load.o
 	./if_not_there on_sparc_sunos5 $(RANLIB) gc.a || cat /dev/null
 #	ignore ranlib failure; that usually means it doesn't exist, and isn't needed