nested class access control in C++

Question

Can inner class access a private member variable of its enclosing class? There seems to be some contradictions on the internet and compiler. Compile (g++ on cygwin) allow

Answer 1

This issue has been addressed in Defect Report #10 and Defect Report #45.

The original and the current C++ language standard does not grant the nested class any extra access rights, i.e. it has no privileges when accessing members of the enclosing class. Nested classes are just ordinary completely independent classes, which just happen to be declared inside some other class.

But according to the proposed resolution in the Defect Report #45, the nested class should be given full access rights to the members of the enclosing class. I.e. the nested class should itself be considered a member of the enclosing class and should enjoy all access rights normally granted to members.

Last time I checked, the work on this defect was not finalized yet. Some compilers already implement what they think the new specification will require, i.e. full access rights to nested classes (see the proposed resolution to the DR#45). Some compilers stick to the letter of the current standard. This is why you might still observe some inconsistency between different compilers with regard to access rights granted to nested classes.