1make: "varmod-loop-delete.mk" line 20: Cannot delete variable "VAR" while it is used 2 while evaluating "${:U:@VAR@@} rest of the value" with value "" 3 while evaluating variable "VAR" with value "${:U:@VAR@@} rest of the value" 4make: Fatal errors encountered -- cannot continue 5make: stopped making "all" in unit-tests 6exit status 1 7