ifeq "$(wildcard distrib/)" "" # We're in a bindist .PHONY: default default: @echo 'Run "make install" to install' @false .PHONY: install install: $(MAKE) -r --no-print-directory -f ghc.mk install BINDIST=YES NO_INCLUDE_DEPS=YES .PHONY: show show: $(MAKE) -r --no-print-directory -f ghc.mk $@ else # The problem we need to solve is as follows. # # GNU make supports included Makefiles, and it is clever enough to try # to update those Makefiles when they are out-of-date or missing. It # first reads all the Makefiles, and then tries to build each one if # it is out-of-date, using the rules in the Makefiles themselves. # When it has brought all the Makefiles up-to-date, it restarts itself # to read the newly-generated Makefiles. # # This works fine, unless there are dependencies *between* the # Makefiles. For example in the GHC build, for each package we have a # package-data.mk file which is generated by the ghc-cabal program, # and we have a .depend file. The .depend file cannot be generated # until package-data.mk has been generated and make has been restarted # to read in its contents, because it is the package-data.mk file that # tells us which modules are in the package. But make always makes # all the Makefiles before restarting - it doesn't take into account a # dependency between Makefiles and restart itself earlier. # Consider the following makefile: # -------------------- # all : # # include inc1.mk # # inc1.mk : Makefile # echo "X = C" >$@ # # include inc2.mk # # inc2.mk : inc1.mk # echo "Y = $(X)" >$@ # -------------------- # Now try it: # # $ make -f fail.mk # fail.mk:3: inc1.mk: No such file or directory # fail.mk:8: inc2.mk: No such file or directory # echo "X = C" >inc1.mk # echo "Y = " >inc2.mk # make: Nothing to be done for `all'. # make built both inc1.mk and inc2.mk without restarting itself # between the two (even though we added a dependency on inc1.mk from # inc2.mk). # # The solution we adopt in the GHC build system is essentially this: # -------------------- # PHASE = 0 # # ifeq "$(PHASE)" "0" # all : # $(MAKE) PHASE=1 # else # all : # endif # # -include inc1.mk # # inc1.mk : Makefile # echo "X = C" >$@ # # ifneq "$(PHASE)" "0" # include inc2.mk # # inc2.mk : inc1.mk # echo "Y = $(X)" >$@ # endif # # clean : # rm -f inc1.mk inc2.mk # -------------------- # That is, every time make is invoked, we force it to update inc1.mk # and then restart. In the GHC build system we need to divide the # build into 4 phases in fact, with a restart between each phase. See # ghc.mk for the details on what happens in each phase and why. default : all @: # No need to update makefiles for these targets: REALGOALS=$(filter-out clean clean_% distclean maintainer-clean show,$(MAKECMDGOALS)) # NB. not the same as saying '%: ...', which doesn't do the right thing: # it does nothing if we specify a target that already exists. .PHONY: $(REALGOALS) $(REALGOALS) all: @echo "===--- updating makefiles phase 0" $(MAKE) -r --no-print-directory -f ghc.mk phase=0 just-makefiles @echo "===--- updating makefiles phase 1" $(MAKE) -r --no-print-directory -f ghc.mk phase=1 just-makefiles @echo "===--- updating makefiles phase 2" $(MAKE) -r --no-print-directory -f ghc.mk phase=2 just-makefiles @echo "===--- updating makefiles phase 3" $(MAKE) -r --no-print-directory -f ghc.mk phase=3 just-makefiles @echo "===--- finished updating makefiles" $(MAKE) -r --no-print-directory -f ghc.mk $@ binary-dist: rm -f bindist-list $(MAKE) -r --no-print-directory -f ghc.mk bindist BINDIST=YES $(MAKE) -r --no-print-directory -f ghc.mk binary-dist clean distclean maintainer-clean: $(MAKE) -r --no-print-directory -f ghc.mk $@ test ! -d testsuite || $(MAKE) -C testsuite $@ $(filter clean_%, $(MAKECMDGOALS)) : clean_% : $(MAKE) -r --no-print-directory -f ghc.mk $@ show: $(MAKE) -r --no-print-directory -f ghc.mk $@ # If the user says 'make A B', then we don't want to invoke two # instances of the rule above in parallel: .NOTPARALLEL: endif