makefiledependenciesgnu-maketargetprerequisites

Impose an order for the prerequisites of a target

I have a makefile snippet:

all: $(objects)
fresh: clean all
clean: ;rm $(objects)

Here, I want to ensure that when I do make fresh - clean should precede all.

But how can I make sure this, given that when I do make all, clean should not be made?

I can imagine that one way could be like this 

fresh: clean
    make all

Is it the right (or the only) way to solve this issue?

Solution

  • If you use GNU make:

    all:
    @echo $@
    @sleep 1
    @echo end $@

clean:
    @echo $@
    @sleep 1
    @echo end $@

fresh:: clean
fresh:: all

.PHONY: clean fresh all

    Please note the double colon after targets fresh! See the documentation:

    The double-colon rules for a target are executed in the order they appear in the makefile.

    If you run make -j2 fresh it shows it works as expect:

    clean
end clean
all
end all

    But with fresh:: clean all doesn't work properly parallel (maybe unexpected).

    With BSD make:

     all:
    @echo $@
    @sleep 1
    @echo end $@

clean:
    @echo $@
    @sleep 1
    @echo end $@

fresh:  clean all
    @echo $@

.ORDER: clean all
.PHONY: clean all fresh

    Note the line begin with .ORDER. It works well in parallelization too (see man make). Without parallelization the order of dependencies in line fresh: counts.