exported makefiles not exported to $(shell ...)

[gk]

It is documented that exported makefiles are exported to 'sub-makes'
I was expecting that export directive also exports values to $(shell ... ) 
but apparently this is not the case.
Is by accident or design?

# Makefile

export FOO1:=1
result:=$(shell echo $$FOO1)
$(warning FOO1=$(result))

result:=$(shell export FOO2=2;echo $$FOO2)
$(warning FOO2=$(result))

foo:;
#eof

address@hidden junk]$ make
Makefile:5: FOO1=
Makefile:8: FOO2=2
make: `foo' is up to date.

- Greg Keraunen
http://www.xmake.org
http://www.xmlmake.com