str_concat2
shellErrFlag = str_concat2("-", shell->errFlag);
char *str_concat2(const char *, const char *);
CandidateList_Add(list, str_concat2(cand->prefix, suff->name),
tname = str_concat2(ssuff->name, tsuff->name);
cache_varname = str_concat2(".MAKE.SH1.", expr->name);