[Bug c++/85790] New: c++17 - Access control issue with template argument deduction

[paolo.monteverde at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85790

            Bug ID: 85790
           Summary: c++17 - Access control issue with template argument
                    deduction
           Product: gcc
           Version: 8.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: paolo.monteverde at gmail dot com
  Target Milestone: ---

struct B {
protected:
    static constexpr unsigned i = 0; 
};

template<unsigned= 0>
struct D : public B {
    D(unsigned = B::i) {}
};


int main() {
    D w{};
}


This results in an error related to B::i being protected. No error is detected
if I explicitly declare D being a template class through "D<> w{};".

Command line: `g++ prog.cc -Wall -Wextra -std=c++17`

Check this on https://wandbox.org/permlink/NnoaLEU6p4GZdJzs