Re: [Automake-NG] [PATCH] [ng] dirstamp: remove, use inlined parent directory creation instead

[Akim Demaille]

Le 21 mai 2012 à 16:19, Stefano Lattarini a écrit :

> As a first step, instead of emitting rules like:
> 
>    sub/foo.o: sub/foo.c sub/.dirstamp
>        $(CC) $(CFLAGS) sub/foo.c
>    sub/.dirstamp:
>        mkdir sub && touch sub/.dirstamp
> 
> we might simply emit rules like:
> 
>    sub/foo.o: sub/foo.c
>        $(MKDIR_P) $(@D)
>        $(CC) $(CFLAGS) sub/foo.c
> 
> But the above would be quite wasteful if we really called $(MKDIR_P) for
> every created object file, since the directory $(@D) will likely already
> exist (in an in-tree build, it will exist unconditionally and beforehand,
> and in a VPATH build will exists after the first object file in it has
> been created).

Maybe order-only prerequisites can help here?

address@hidden /tmp $ cat Makefile
all: foo/bar

foo/bar: | foo
        echo $@ >$@

foo:
        mkdir $@
address@hidden /tmp $ make
mkdir foo
echo foo/bar >foo/bar
address@hidden /tmp $ make
make: Nothing to be done for `all'.
address@hidden /tmp $ rm foo/bar
address@hidden /tmp $ make
echo foo/bar >foo/bar
address@hidden /tmp $ make
make: Nothing to be done for `all'.