minifier: dce + var hosting edge cases

[underfin]

Input

if (false) {
	for (var a; unknownGlobal && true; unknownGlobal && true) var b;
} else {
	console.log(a, b);
}

if (((() => console.log('effect'))(), true)) {
} else {
	var c = 1;
	for (var c; unknownGlobal && true; unknownGlobal && true) var d;
}
console.log(c, d);

Output

console.log(a, b);
console.log(c, d);

Expected

var b, a; {
	console.log(a, b);
}

var c, d; if (((() => console.log('effect'))(), true)) ;
console.log(c, d);

The a,b,c,d need to hosted, the ((() => console.log('effect'))() need to preserve.

Found the case at https://github.com/rollup/rollup/blob/master/test/form/samples/hoisted-vars-in-dead-branches/main.js

[7086cmd]

Is the swc's result better than the expected?

var d, c;
console.log(void 0, void 0), console.log('effect'), console.log(c, d);

Closure Compiler's

var d,c,b,a;console.log(a,b);(()=>console.log("effect"))();console.log(c,d);

[Boshen]

I need to spend some time rewriting this part of the code, it's a bit more involved.