1
 2foo := bletch garf
 3auto_var = undefined CC MAKETEST MAKE foo CFLAGS WHITE @
 4av = $(foreach var, $(auto_var), $(origin $(var)) )
 5override WHITE := BLACK
 6.RECIPEPREFIX = >
 7all: auto
 8> @echo $(origin undefined)
 9> @echo $(origin CC)
10> @echo $(origin MAKETEST)
11> @echo $(origin MAKE)
12> @echo $(origin foo)
13> @echo $(origin CFLAGS)
14> @echo $(origin WHITE)
15> @echo $(origin @)
16auto :
17> @echo $(av)