[Bug c++/77419] Inconsistent behavior with auto& and __attribute__((unused))

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77419

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2018-09-14
                 CC|                            |msebor at gcc dot gnu.org
     Ever confirmed|0                           |1
      Known to fail|                            |6.4.0, 7.3.0, 8.2.0, 9.0

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
Confirmed with the top of trunk (GCC 9):

$ cat t.C && gcc -O2 -S -Wall t.C

int main() {
    int __attribute__((unused)) int_var_unused = 42;
    int int_var = 42;
    int& __attribute__((unused)) int_ref = int_var;
    auto __attribute__((unused)) auto_var_unused = 42;
    auto auto_var = 42;
    auto& __attribute__((unused)) auto_ref = auto_var;
    return 0;
}
t.C: In function ‘int main()’:
t.C:8:35: warning: unused variable ‘auto_ref’ [-Wunused-variable]
8 |     auto& __attribute__((unused)) auto_ref = auto_var;
  |                                   ^~~~~~~~