make: In the :@ modifier, the variable name "${:Ubar:S,b,v,}" must not contain a dollar
	while evaluating variable "VAR" with value "value"
	in command "@echo ${VAR:Uvalue:@${:Ubar:S,b,v,}@x${var}y@:Q}"
	in target "mod-loop-varname"
exit status 2