RE: Targets directory name concatenation strangeness

[Martin Dorey]

You're trying to use an automatic variable in a scope where it doesn't have the 
value you want.  make -p is how I'd debug such:

address@hidden:~/tmp/benjamin-cama-2017-08-03$ cat Makefile
SUBDIR = $(@D)
$(SUBDIR)/target-%:
address@hidden:~/tmp/benjamin-cama-2017-08-03$ make -n -p 2>&1 | grep target- | 
grep -v FEATURES
/target-%:
address@hidden:~/tmp/benjamin-cama-2017-08-03$

The documentation, specifically 
https://www.gnu.org/software/make/manual/html_node/Automatic-Variables.html, 
speaks directly to this case:

"It’s very important that you recognize the limited scope in which automatic 
variable values are available: they only have values within the recipe. In 
particular, you cannot use them anywhere within the target list of a rule; they 
have no value there and will expand to the empty string."

-----Original Message-----
From: Bug-make [mailto:address@hidden On Behalf Of Benjamin Cama
Sent: Thursday, August 03, 2017 08:37
To: Edward Welbourne
Cc: address@hidden
Subject: Targets directory name concatenation strangeness

OK, new subject as this specific behavior gets stranger.

Le jeudi 03 août 2017 à 17:27 +0200, Benjamin Cama a écrit :
> Le jeudi 03 août 2017 à 15:06 +0000, Edward Welbourne a écrit :
> > Benjamin Cama (3 August 2017 17:00)
> > > Well, I tried:
> > >
> > >        SUBDIR = $(dir $@)
> > >        $(SUBDIR)/target-%:
> > >          …
> > >
> > > But it doesn't work. But without a slash (which is already present at
> > > the end of $(SUBDIR)), it actually works!:
> > >
> > >        SUBDIR = $(dir $@)
> > >        $(SUBDIR)target-%:
> > >          …
> > >
> > > Is this a bug?
> > 
> > No: thing/target-suffix and thing//target-suffix are different names.
> > They may be functionally equivalent, but make just sees different
> > strings, one with a doubled-slash, the other with just one slash.
> 
> Well, the thing is that passing target names to make with any number of
> slashes normalize it to one, so I tended to think that the definition
> followed the same normalization. Thanks for the explanation, then.

Still, when I try to concatenate the slashless directory name and the
file name with a slash in between, it does not work!:

        SUBDIR = $(@D)
        $(SUBDIR)/target-%:
                echo $(SUBDIR)

does not work:

        $ make foo/target-1234
        make: *** No rule to make target 'foo/target-1234'. Arrêt.

Without the slash, it works:

        $ make foo/target-1234
        echo foo
        foo

This looks very strange to me.

-- 
Benjamin Cama - Tél : 258


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