[Bug c++/68301] New: self-dependent reference member initialization not diagnosed

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68301

            Bug ID: 68301
           Summary: self-dependent reference member initialization not
                    diagnosed
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

While verifying that bug 68208 has been fixed (it has been), I noticed that
other, slightly more involved cases of reference members than the trivial
"m(m)" in the bug are not diagnosed.  For example, the following program which
is diagnosed by Clang as shown is accepted by GCC without a warning even with
-Wall and -Wextra.

 cat u.cpp && /build/llvm-trunk/bin/clang++ -S -Wall -o/dev/null u.cppstruct S
{
    const int &r1, &r2;

    S ():
    r1 (r2),
    r2 (r1)
    { }
};
u.cpp:5:9: warning: reference 'r2' is not yet bound to a value when used here
      [-Wuninitialized]
    r1 (r2),
        ^
1 warning generated.