Bug in unless with conditional assignment

[stephank]

Something like:

unless foo ||= bar
    baz()

...is compiled as:

if (!foo || (foo = bar)) {
    baz();
}

...which is not applying the 'not' operator to the entire result.

I was expecting this:

if (!(foo || (foo = bar))) {
    baz();
}

The below examples all have a falsy condition result, but swap the assignment result and position of the conditional assignment. I believe the last example is incorrect. This is on master (ef0cb46 at the time of writing) and 1.2.0.

# coffee -s
foo = null
foo ||= no
unless foo
  console.log('yay')
^D
yay

# coffee -s
foo = null
unless foo ||= no
  console.log('yay')
^D
yay

# coffee -s
foo = null
foo ||= yes
unless foo
  console.log('boo')
^D

# coffee -s
foo = null
unless foo ||= yes
  console.log('boo')
^D
boo

[michaelficarra]

Yep, it looks like ||= isn't being negated properly. We're not adding the necessary parentheses.

edit: A temporary solution is adding parentheses around the expression yourself. Apparently they're being preserved...

$ coffee -bep 'a = null; b unless a ||= c'
var a;

a = null;

if (!a || (a = c)) {
  b;

}
$ coffee -bep 'a = null; b unless (a ||= c)'
var a;

a = null;

if (!(a || (a = c))) {
  b;

}