make: "directive-for-empty.mk" line 21: 2 make: "directive-for-empty.mk" line 34: Missing argument for ".error" make: "directive-for-empty.mk" line 34: Missing argument for ".error" make: "directive-for-empty.mk" line 34: Missing argument for ".error" For: end for 1 For: loop body: # The identifier 'empty' can only be used in conditions such as .if, .ifdef or # .elif. In other lines the string 'empty(' must be preserved. CPPFLAGS+= -Dmessage="empty(i)" # There may be whitespace between 'empty' and '('. .if ! empty (i) . error .endif # Even in conditions, the string 'empty(' is not always a function call, it # can occur in a string literal as well. .if "empty\(i)" != "empty(i)" . error .endif # In comments like 'empty(i)', the text must be preserved as well. # # Conditions, including function calls to 'empty', can not only occur in # condition directives, they can also occur in the modifier ':?', see # varmod-ifelse.mk. CPPFLAGS+= -Dmacro="${empty(i):?empty:not-empty}" make: Fatal errors encountered -- cannot continue make: stopped in unit-tests exit status 1