Get rid of .fake_file dependency

From now on OBJDIR is order-only dependency

mk/def_rules.mk

@@ -61,10 +61,9 @@ LINK.cc = $(call echo_cmd,LINK $@) $(CXX) $(CXXFLAGS) $(CPPFLAGS) $(LDFLAGS) $(T
 %.CPPFLAGS : %
 	@echo $(CPPFLAGS)
 
-# In this build system all objects are in a separate directory and
-# I make sure this directory exists by the dependency on this fake file
-%/$(OBJDIR)/.fake_file:
-	@[ -d $(dir $@) ] || mkdir -p $(dir $@); touch $@
+# Create the output directory for build targets.
+%/$(OBJDIR):
+	@mkdir -p $@
 
 # Generic rules.  Again, since the output is in different directory than
 # source files I cannot count on the built in make rules.  So I keep
@@ -81,19 +80,19 @@ LINK.cc = $(call echo_cmd,LINK $@) $(CXX) $(CXXFLAGS) $(CPPFLAGS) $(LDFLAGS) $(T
 # COMPILE.cmo.ml = $(call echo_cmd,CAML $<) $(CAML) -c
 # COMPILE.cmx.ml = $(call echo_cmd,CAMLOPT $<) $(CAMLOPT) -c
 # together with corresponding two entries in 'skeleton' below:
-# $(OBJPATH)/%.cmo $(OBJPATH)/%.cmx: $(1)/%.ml $(OBJPATH)/.fake_file
+# $(OBJPATH)/%.cmo $(OBJPATH)/%.cmx: $(1)/%.ml | $(OBJPATH)
 # 	$(value COMPILECMD_TD)
 
 COMPILECMD = $(COMPILE$(suffix $<)) -o $@ $<
 COMPILECMD_TD = $(COMPILE$(suffix $@)$(suffix $<)) -o $@ $<
 
 define skeleton
-$(OBJPATH)/%.o: $(1)/%.cpp $(OBJPATH)/.fake_file
+$(OBJPATH)/%.o: $(1)/%.cpp | $(OBJPATH)
 	$(value COMPILECMD)
 
-$(OBJPATH)/%.o: $(1)/%.cc $(OBJPATH)/.fake_file
+$(OBJPATH)/%.o: $(1)/%.cc | $(OBJPATH)
 	$(value COMPILECMD)
 
-$(OBJPATH)/%.o: $(1)/%.c $(OBJPATH)/.fake_file
+$(OBJPATH)/%.o: $(1)/%.c | $(OBJPATH)
 	$(value COMPILECMD)
 endef

mk/footer.mk

@@ -48,7 +48,7 @@ $(foreach v,$(INHERIT_DIR_VARS_$(d)),$(if $($(v)_$(d)),,$(eval $(v)_$(d) := $($(
 $(foreach sd,$(SUBDIRS),$(eval $(call include_subdir_rules,$(sd))))
 
 .PHONY: dir_$(d) clean_$(d) clean_extra_$(d) clean_tree_$(d) dist_clean_$(d)
-.SECONDARY: $(OBJPATH)/.fake_file
+.SECONDARY: $(OBJPATH)
 
 # Whole tree targets
 all :: $(TARGETS_$(d))

mk/skel.mk

@@ -124,14 +124,15 @@ SOEXT := $(or $(SOEXT),so)
 ########################################################################
 
 # I define these for convenience - you can use them in your command for
-# updating the target.  Since I'm using fake file dependency to make
-# sure the OBJDIR exists I filter it out here.  Mnemonic for these
-# ? ^ versions is Real (that is not fake :))
+# updating the target.
 DEP_OBJS = $(filter %.o, $^)
 DEP_ARCH = $(filter %.a, $^)
 DEP_LIBS = $(addprefix -L,$(dir $(filter %.$(SOEXT), $^))) $(patsubst lib%.$(SOEXT),-l%,$(notdir $(filter %.$(SOEXT), $^)))
-?R = $(filter-out %/.fake_file,$?)
-^R = $(filter-out %/.fake_file,$^)
+
+# Kept for backward capability - you should stop using these since I'm
+# now not dependend on $(OBJDIR)/.fake_file any more
+?R = $?
+^R = $^
 
 # Targets that match this pattern (make pattern) will use rules defined
 # in:
@@ -172,9 +173,8 @@ SRCS_VPATH := src
 # target's suffix and corresponding MAKECMD variable.  For example %.a
 # are # updated by MAKECMD.a (exemplary setting below).  If the target
 # is not filtered out by AUTO_TGTS and there's neither _CMD nor suffix
-# specific command to build the target DEFAULT_MAKECMD is used.  See
-# above for the explanation of the R versions of ? and ^ variables.
-MAKECMD.a = $(call echo_cmd,AR $@) $(AR) $(ARFLAGS) $@ $(?R) && $(RANLIB) $@
+# specific command to build the target DEFAULT_MAKECMD is used.
+MAKECMD.a = $(call echo_cmd,AR $@) $(AR) $(ARFLAGS) $@ $? && $(RANLIB) $@
 MAKECMD.$(SOEXT) = $(LINK.cc) $(DEP_OBJS) $(DEP_ARCH) $(DEP_LIBS) $(LIBS_$(@)) $(LDLIBS) -shared -o $@
 DEFAULT_MAKECMD = $(LINK.cc) $(DEP_OBJS) $(DEP_ARCH) $(DEP_LIBS) $(LIBS_$(@)) $(LDLIBS) -o $@
 
@@ -214,7 +214,7 @@ abs_deps := $$(filter /%,$$(DEPS_$(1)))
 rel_deps := $$(filter-out /%,$$(DEPS_$(1)))
 abs_deps += $$(addprefix $(OBJPATH)/,$$(rel_deps))
 -include $$(addsuffix .d,$$(basename $$(abs_deps)))
-$(1): $$(abs_deps) $(if $(findstring $(OBJDIR),$(1)),$(OBJPATH)/.fake_file,)
+$(1): $$(abs_deps) $(if $(findstring $(OBJDIR),$(1)),| $(OBJPATH),)
 	$$(or $$(CMD_$(1)),$$(MAKECMD$$(suffix $$@)),$$(DEFAULT_MAKECMD))
 endef