dollar_expand
char *dollar_expand(int *, const char *string, ...);
if ((arg2 = dollar_expand(&r, arg)) == NULL || r) {
cp = p = dollar_expand(&err, fwdspec);
char *str = dollar_expand(NULL, (x)); \
ret = dollar_expand(&parseerr, "a${BAZ}");
ret = dollar_expand(&parseerr, "${BAZ}b");
ret = dollar_expand(&parseerr, "a${BAZ}b");
ret = dollar_expand(&parseerr, "${");
ret = dollar_expand(&parseerr, "${F");
ret = dollar_expand(&parseerr, "${FO");
ret = dollar_expand(&parseerr, "${}");