Don't use beforedepend to complicate and break things. Just put

generated source files in SRCS.

Don't use MANDEPEND to complicate things.  Just set MAN1 and put
generated man pages in CLEANFILES.

Added temporary files to CLEANFILES.

Partly fixed a potentially fatal bug involving the yacc header.
We generate eqn.cc (even if there is a version of it in the source
directory older than eqn.y) and a matching eqn.tab.h, but only use
the possibly-non-matching eqn.tab.h in the source directory.  This
works because Cygnus's yacc happened to generate a y.tab.h identical
to the current generated one.  The correct version will be used
when the wrong version is deleted from the source tree.  Kludge to
get the header generated early enough.  Yacc headers are mishandled
everywhere they are renamed (and used).

Generate neqn at build time, not at install time.

Fixed some style bugs.

gnu/usr.bin/groff/eqn/Makefile

@@ -1,26 +1,25 @@
-# Makefile for eqn
+#	$Id$
 
 PROG=		eqn
-MAN1=		eqn.1 neqn.1
-SRCS=		main.cc lex.cc  box.cc limit.cc list.cc over.cc text.cc\
+SRCS=		eqn.cc eqn.tab.h main.cc lex.cc \
+		box.cc limit.cc list.cc over.cc text.cc \
 		script.cc mark.cc other.cc delim.cc sqrt.cc pile.cc special.cc
-OBJS=		eqn.o
-#CFLAGS+=	-I. -I${.CURDIR}/../include
-LDADD+=		${LIBGROFF}
-DPADD+=		${LIBGROFF}
+CFLAGS+=	-I.
+DPADD=		${LIBGROFF}
+LDADD=		${LIBGROFF}
+MAN1=		eqn.1 neqn.1
+CLEANFILES=	eqn.cc eqn.tab.h ${MAN1} neqn y.tab.c y.tab.h
 
-MANDEPEND=	neqn.1 eqn.1
-CLEANFILES+=	eqn.cc eqn.tab.h neqn ${MANDEPEND}
+all: neqn
 
-afterinstall:	neqn
+beforeinstall: neqn
 	${INSTALL} ${COPY} -o ${BINOWN} -g ${BINGRP} -m ${BINMODE} neqn \
-		${DESTDIR}${BINDIR}
+	    ${DESTDIR}${BINDIR}
 
-beforedepend: eqn.cc
+eqn.tab.h: eqn.cc
 
 .include "../Makefile.cfg"
 .include <bsd.prog.mk>
 
-neqn:   ${DIST_DIR}/neqn.sh
-	sed -e 's/@g@/${g}/g' ${DIST_DIR}/neqn.sh > neqn
-
+neqn: ${DIST_DIR}/neqn.sh
+	sed -e 's/@g@/${g}/g' ${.ALLSRC} > ${.TARGET}