What's wrong about using variables in `define'?

[Pan ruochen]

Hi All,
I want to debug a complex called function using temporary variables in `define'.
But something seems wrong.

$cat Makefile
define check
tmpvar=$1
$(warning $(tmpvar))
tmpvar=$2
$(warning $(tmpvar))
endef
$(eval $(call check,V1,V2))
all:
$make -f Makefile
Makefile:7:
Makefile:7:
make: Nothing to be done for `all'.

But if I modify the script to:
$cat Makefile
define check
$(warning $1)
$(warning $2)
endef
$(eval $(call check,V1,V2))
all:
$make
Makefile:4: V1
Makefile:4: V2
make: Nothing to be done for `all'.

Everything is okay. What's wrong about using variables in `define's?

Best Regards,
PRC
Apr 6, 2008