Why is_admin_of_role() use ROLERECURSE_MEMBERS rather than ROLERECURSE_PRIVS?

Hi,

When reading the code, I find is_admin_of_role() use ROLERECURSE_MEMBERS while select_best_admin() use ROLERECURSE_PRIVS.

Why they are dismatch?

The following case will have is_admin_of_role() return true and select_best_admin() return InvalidOid:

create user u1;
create user u2;
create user u3;
create user u4;
grant u2 to u1 with admin true ;
grant u3 to u2 with admin true ;
revoke inherit option for u2 from u1 ;
set session authorization u1;
grant u3 to u4;

The "grant u3 to u4;" will report error "no possible grantors" rather than "permission denied to grant role".

Is this the expected behavior?

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Regards,
ChangAo Chen