make: Bad conditional expression `variable expression == "literal"' in variable expression == "literal"?bad:bad
make: "varmod-ifelse.mk" line 27: Malformed conditional (${${:Uvariable expression} == "literal":?bad:bad})
make: Bad conditional expression ` == ""' in  == ""?bad-assign:bad-assign
make: Bad conditional expression ` == ""' in  == ""?bad-cond:bad-cond
make: "varmod-ifelse.mk" line 44: Malformed conditional (${${UNDEF} == "":?bad-cond:bad-cond})
make: Fatal errors encountered -- cannot continue
make: stopped in unit-tests
exit status 1