[Bug c++/77434] New: warn about suspicious precedence of ternary operator (?:)

[manu at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77434

            Bug ID: 77434
           Summary: warn about suspicious precedence of ternary operator
                    (?:)
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: manu at gcc dot gnu.org
  Target Milestone: ---

Code such as the following are suspicious:

int foo(int a, int b)
{
return (a > 0 && a <= (b == 1) ? 1 : 2);
}

some users may expect it to be equivalent to a <= ((b==1) ? 1 :2)
but it is in fact equivalent to (a <= (b == 1)) ? 1 : 2

We should warn with -Wparenthesis

Real bug in GCC: PR77421

static void
output_loc_operands (dw_loc_descr_ref loc, int for_eh_or_skip)
{
  unsigned long die_offset
    = get_ref_die_offset (val1->v.val_die_ref.die);
  ....
  gcc_assert (die_offset > 0
        && die_offset <= (loc->dw_loc_opc == DW_OP_call2)
             ? 0xffff
             : 0xffffffff);
  ....
}