[Bug c++/127279] New: Direct init of member reference disregards explicit conversions

[pj at patrickjohnston dot org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127279

            Bug ID: 127279
           Summary: Direct init of member reference disregards explicit
                    conversions
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pj at patrickjohnston dot org
  Target Milestone: ---

Testcase:

struct S
{
    int t{};

    explicit operator int&()
    {
        return t;
    }
};

struct Wrapper
{
    int& t;

    template<typename T>
    Wrapper(T&& tt)
        : t(tt)
    {}
};

int main()
{
    S s;
    int& x(s);
    Wrapper w(s);
}

Live: https://godbolt.org/z/qqvE9nKP8

GCC correctly initialises `x` using `S::operator int`, but fails to initialise
`Wrapper::t`, which should have the same initialisation semantics

Init semantics I believe are
    https://eel.is/c++draft/dcl.init.general#15.2
 -> https://eel.is/c++draft/dcl.init.ref#5.1.2
 -> https://eel.is/c++draft/over.match.ref

and then it's direct init because https://eel.is/c++draft/dcl.init.general#14.1

This issue doesn't appear to occur when initialising a non-reference type.