[Bug bootstrap/43681] New: bootstrap fails with "unused" var message for an apparently used var.

[iains at gcc dot gnu dot org]

158099.
cc1: warnings being treated as errors
/GCC/gcc-live-trunk/gcc/expr.c: In function
‘block_move_libcall_safe_for_call_parm’:
/GCC/gcc-live-trunk/gcc/expr.c:1254:8: error: variable ‘fn’ set but not
used
make[3]: *** [expr.o] Error 1

BUT:
======
static bool
block_move_libcall_safe_for_call_parm (void)
{
#if defined (REG_PARM_STACK_SPACE)
1254==>>>  tree fn;
#endif

  /* If arguments are pushed on the stack, then they're safe.  */
  if (PUSH_ARGS)
    return true;

  /* If registers go on the stack anyway, any argument is sure to clobber
     an outgoing argument.  */
#if defined (REG_PARM_STACK_SPACE)
  fn = emit_block_move_libcall_fn (false);
  if (OUTGOING_REG_PARM_STACK_SPACE ((!fn ? NULL_TREE : TREE_TYPE (fn)))
      && REG_PARM_STACK_SPACE (fn) != 0)
    return false;
#endif

  /* If any argument goes in memory, then it might clobber an outgoing


-- 
           Summary: bootstrap fails with "unused" var message for an
                    apparently used var.
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: blocker
          Priority: P3
         Component: bootstrap
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: iains at gcc dot gnu dot org
GCC target triplet: powerpc-apple-darwin9


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43681