Errors with winxed optional params

generated.pir

.sub 'whatever' :subid('WSubId_2')
        .param string __ARG_1 :optional
        .param int __opt_flag__ARG_1 :opt_flag
    if __opt_flag__ARG_1 goto __label_1
.annotate 'line', 10
    $P1 = WSubId_1()
    set __ARG_1, $P1
  __label_1:
.const 'Sub' WSubId_1 = "WSubId_1"
.annotate 'line', 12
    concat $S1, "In whatever: ", __ARG_1
    say $S1
.annotate 'line', 13

.end # whatever

gistfile1.txt

function foo(var x = self.method()) 
    - self is null
   
function foo(int x = false)
    - ugly error about unexpanded constant


const int CONST_BAR = 4;
function foo(int x = CONST_BAR)
    - ugly error about unexpanded constant

namespace Bar { function baz() { } }
function foo(var x = Bar.baz())
    - Attempt to call method on something that isn't an object