Incorrect transformation of mixed boolean expression in unless statement

[ghost]

decaffeinate is producing the wrong JavaScript based on my CoffeeScript input:

func = ->
  return 'condVal' unless cond1 and cond2 or cond3
  'val'

Link to REPL

I get this output:

func = function() {
  if (!(cond1 || !cond2) && !cond3) { return 'condVal'; }
  return 'val';
};

Here's what I expect it to be instead: (Coffee's compiler)

func = function() {
  if (!(cond1 && cond2 || cond3)) { return 'condVal'; }
  return 'val';
};

Or something more similar to decaffeinate's:

func = function() {
  if ((!cond1 || !cond2) && !cond3)) { return 'condVal'; }
  return 'val';
};

[ghost]

Looks like the bug is in MainStage since the output of NormalizeStage looks okay.

[ghost]

I get that we're applying DeMorgan's law to the unless statements

!(  cond1 &&  cond2  ||  cond3)
!( (cond1 &&  cond2) ||  cond3) # for clarity (what Coffescript's compiler does)
  !(cond1 &&  cond2) && !cond3) # top level demorgans
  (!cond1 || !cond2) && !cond3) # Maybe this?

But I haven't looked at the code at all, so I have no idea what decaffeinate's actually doing

[eventualbuddha]

This is the part that triggers it:

decaffeinate/src/stages/main/patchers/ConditionalPatcher.ts

Lines 98 to 100 in 4da99dd

	if (this.node.isUnless) {
	this.condition.negate();
	}

Which calls e.g. this:

decaffeinate/src/stages/main/patchers/LogicalOpPatcher.ts

Lines 42 to 46 in 4da99dd

	negate(): void {
	this.negated = !this.negated;
	this.left.negate();
	this.right.negate();
	}

[eventualbuddha]

A note for future me or whoever might try to fix this: the bug is that the ! is inserted before the parenthesis at !(cond1 when it should be inside the parenthesis like (!cond1. This feels more like a string insertion / order of operations bug than a logic error, like both the ( and the ! are inserted at the same position but their order is the reverse of what it should be.

[eventualbuddha]

The ! is inserted at the wrong time because the call to negate() immediately inserts a ! rather than marking the patcher as negated. This may require a non-trivial refactor.