475843 - Different (more) bytecode used for group assignment that is inside parens

Status: RESOLVED DUPLICATE of bug 461269

(Core :: JavaScript Engine, defect)

Description

[Jesse Ruderman]

js> var f = function() { ([a] = [3]); };

js> f
function () {
    [a] = [3];
}

js> dis(f)
flags: LAMBDA INTERPRETED
main:
00000:  int8 3
00002:  newarray 1
00006:  dup
00007:  zero
00008:  getelem
00009:  bindname "a"
00012:  qnamepart "a"
00015:  enumelem
00016:  pop
00017:  stop

Source notes:
  0:     6 [   6] decl     offset 3
  2:    15 [   9] xdelta  
  3:    15 [   0] pcbase   offset 6

js> dis(eval(uneval(f)))
flags: LAMBDA INTERPRETED
main:
00000:  int8 3
00002:  getlocal 0
00005:  bindname "a"
00008:  qnamepart "a"
00011:  enumelem
00012:  popn 1
00015:  stop

Source notes:
  0:     2 [   2] pcdelta  offset 3
  2:    11 [   9] xdelta  
  3:    11 [   0] pcbase   offset 6

Comment 1

[Blake Kaplan (:mrbkap) (inactive)]

Brendan's right -- we shouldn't whack these moles any longer.

Comment 2

[Jason Orendorff [:jorendorff]]

In current tracemonkey tip:

js> var f = function() { ([a] = [3]); };
js> f
function () {
    [a] = [3];
}
js> dis(f);
flags: LAMBDA NULL_CLOSURE
main:
00000:  int8 3
00002:  getlocal 0
00005:  bindname "a"
00008:  qnamepart "a"
00011:  enumelem
00012:  popn 1
00015:  stop

Source notes:
  0:     2 [   2] pcdelta  offset 3
  2:    11 [   9] xdelta  
  3:    11 [   0] pcbase   offset 6

Comment 3

[Brendan Eich [:brendan]]

Jason used the BIG mole-gun. ;-)

/be