X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fdocs%2Fusers_guide%2Futils.lit;fp=ghc%2Fdocs%2Fusers_guide%2Futils.lit;h=6ec326e6f9ff5f9af7307653d57911bcfc25cf50;hb=a7e6cdbfc4f27c2e0ab9c12ebe6431c246c74c6d;hp=d007621521d41b4ff303816058af0c11c1d46189;hpb=26741ec416bae2c502ef00a2ba0e79050a32cb67;p=ghc-hetmet.git

diff --git a/ghc/docs/users_guide/utils.lit b/ghc/docs/users_guide/utils.lit
index d007621..6ec326e 100644
--- a/ghc/docs/users_guide/utils.lit
+++ b/ghc/docs/users_guide/utils.lit
@@ -27,7 +27,9 @@ HCFLAGS = -fhaskell-1.3 -cpp -hi-diffs $(EXTRA_HC_OPTS)
 SRCS = Main.lhs Foo.lhs Bar.lhs
 OBJS = Main.o   Foo.o   Bar.o
 
-.SUFFIXES : .o .lhs
+.SUFFIXES : .o .hi .lhs
+.o.hi:
+	@:
 .lhs.o:
         $(RM) $@
         $(HC) -c $< $(HCFLAGS)
@@ -37,6 +39,14 @@ cool_pgm : $(OBJS)
         $(HC) -o $@ $(HCFLAGS) $(OBJS)
 \end{verbatim}
 
+Note the cheesy \tr{.o.hi} rule: It records the dependency of the
+interface (\tr{.hi}) file on the source.  The rule says a \tr{.hi}
+file can be made from a \tr{.o} file by doing... nothing.  Which is
+true.
+
+(Sophisticated \tr{make} variants may achieve some of the above more
+elegantly.  What we've shown should work with any \tr{make}.)
+
 The only thing lacking in the above \tr{Makefile} is interface-file
 dependencies.  If \tr{Foo.lhs} imports module \tr{Bar} and the
 \tr{Bar} interface changes, then \tr{Foo.lhs} needs to be recompiled.
@@ -64,6 +74,9 @@ effect.  However, a \tr{make} run that does nothing {\em does} mean
 mutually-recursive modules but, again, it may take multiple
 iterations to ``settle.''
 
+To see \tr{mkdependHS}'s command-line flags, give it a duff flag,
+e.g., \tr{mkdependHS -help}.
+
 %************************************************************************
 %*                                                                      *
 \subsection[hstags]{Emacs `TAGS' for Haskell: \tr{hstags}}