Re: make 3.81rc2: automatic variables strip leading "./"

[Paul D. Smith]

%% "Angel Tsankov" <address@hidden> writes:

  >> This is not limited to this release candidate: GNU make has behaved
  >> like this for a very long time.  However, it was only recently
  >> reported.
  >> 
  >> See Savannah bug #10708.
  >> 
  >> https://savannah.gnu.org/bugs/index.php?func=detailitem&item_id=10708
  >> 
  >> 
  >> This is not targeted to be fixed in GNU make 3.81 however.

  at> What do you mena by "fixed" - as far as I can see, this is not
  at> bug, is it?

I think it could be considered a bug, yes.

  at> In order to achieve the desired behaviour now I need a way to
  at> check if patsubst has made any substitutions when called OR a way
  at> to test the result of patsubst to the third argument. How is this
  at> done?

I think you're misunderstanding the issue.  It's true that the example
in the bug is needlessly complex, which leads to misunderstandings about
what the bug actually is... a lesson to us all to make the example as
simple as possible and to leave out everything not directly related to
reproducing the bug.

Consider this makefile:

    ./foo:      ; @echo $@

One would expect (_I_ would expect) this to print:

    ./foo

because that's the target name in the makefile.  But in fact it prints:

    foo

because make canonicalizes the target names so it can match them up;
consider this:

    foo: bar
    ./foo:      ; @echo $@

does "./foo" depend on bar?  Make says yes and I think it's right.  But
I also think "$@" should be the literal name of the target associated
with the command script.

The same thing happens for prerequisites and "$<" etc... although this
is less obvious; consider:

    foo: ./bar  ; @echo $<

    bar:        ; @:

Now, does this print "bar" or "./bar"?


Anyway, there is no patsubst called here, and there's no way to know
whether the target had a "./" prefix or not (unless you do it yourself
by setting your own variable or something rather than relying on $@ etc.)

It cannot be done.

-- 
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