pass parent stem value to prerequisite rule

[Martin d'Anjou]

Hi,

I can't figure out how to pass the parent stem value to a prerequisite rule:

.SECONDEXPANSION:
rule_%: test=foo
rule_%: parent_stem=$*
rule_%: child_b
  @echo in parent: parent_stem=$(parent_stem)

child_%:
  @echo in child: stem=$*
  @echo in child: test=$(test)
  @echo 'in child: parent_stem=$(parent_stem) --> this should be "a", not "b"'

all: rule_a
  @echo done

$ make
in child: stem=b
in child: test=foo
in child: parent_stem=b --> this should be "a", not "b"
in parent: parent_stem=a
done


The parent stem value is noticeably empty. I tried different
variations, with and without .SECONDEXPANSION:, but no success. Can
this be done?

Thanks,
Martin