[Bug target/81850] New: [mingw/cygwin] -mabi=sysv ignored

[daniel.santos at pobox dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81850

            Bug ID: 81850
           Summary: [mingw/cygwin] -mabi=sysv ignored
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: daniel.santos at pobox dot com
  Target Milestone: ---

In ix86_option_override_internal (i386.c), we check to see if
opts_set->x_ix86_abi is uninitialized by seeing if it's zero:

  if (!opts_set->x_ix86_abi)
    opts->x_ix86_abi = DEFAULT_ABI;

But zero is a valid enum value (i386-opt.h):

/* Available call abi.  */
enum calling_abi
{
  SYSV_ABI = 0,
  MS_ABI = 1
};