Why does redirecting to other makefile execute rules differently?

[Timo Suoranta]

Short story: "make test1" executes rules twice, why? "make test2" works 
as expected.

Long story: I'm trying to have a generic Makefile that detects platform 
using uname and then forwards goals to another Makefile.b. But I am 
getting targets being built multiple times. This happens when the target 
Makefile.b calls $(MAKE). Currently these $(MAKE) commands do not 
specify makefile, and I'd like to keep it that way. So they go to the 
default Makefile after which they come back to Makefile.b. But why do 
rules get executed twice?


# Makefile

.DEFAULT:
        $(MAKE) -f Makefile.b $(MAKECMDGOALS)

# Makefile.b

test1:
        $(MAKE) foo bar

test2:
        $(MAKE) -f Makefile.b foo bar

foo:
        @echo foo

bar:
        @echo bar

--
timo