ufuzz failure

[alexlamsl]

// original code
// (beautified)
var _calls_ = 10, a = 100, b = 10, c = 0;

async function f0(undefined, bar) {
    function f1(arguments_1) {
        function f2(undefined) {
        }
        var b_2 = f2("a");
        async function f3(b_1, let_2) {
            {
                var expr2 = [ (c = 1 + c, (1 <= "undefined") / (NaN >>> 0), 23..toString() & [ , 0 ][1] & (b_1 && (b_1[c = 1 + c, 
                (5 / -3 ^ (5 || this)) - ((0 | 2) ^ 38..toString() / false)] = 25 / 4))) ];
                for await (var key2 of expr2) {
                    c = 1 + c, ((3 | -0) !== "function" <= 22) >= (bar = (bar = 3 || /[a2][^e]+$/) === [] % 5);
                }
            }
        }
        var bar_2 = f3();
        function f4(Infinity_2) {
        }
        var b_2 = f4();
        function f5(bar_2) {
            switch (c = 1 + c, ("undefined" & null) == -4 << 5 && (arguments_1 && ([ arguments_1.in ] = [ (bar_2 && (bar_2[c = 1 + c, 
            ("b" * "function" < (-5 & 4)) >>> ((bar && (bar[c = 1 + c, (c = c + 1, 
            -1 === 23..toString()) << ("c" > Infinity < (undefined **= "bar" << -0))] = 4 == "bar")) >>> true / 1)] &= 3 ^ "undefined")) > (c = c + 1, 
            "c") ]))) {
              case c = 1 + c, (3 + "function") % (this >>> -0) - ((bar_2 = "foo" !== -4) >= (bar_2 && (bar_2[c = 1 + c, 
                bar_2 && (bar_2[typeof f7 == "function" && --_calls_ >= 0 && f7({})] += (([ , 0 ].length === 2 && "b") !== -0 - "") * ("object" << "b" << 4 / 25))] = 25 != this))):
                ;
                break;

              case c = 1 + c, void (24..toString() << "" && (/[a2][^e]+$/ || 1)):
                ;
                break;

              case c = 1 + c, (("a" === 2) <= (22 == ([ , 0 ].length === 2))) + (2 < /[a2][^e]+$/ || 23..toString() && 5):
                ;

              case c = 1 + c, (-2 % 24..toString() >>> (-3 & 23..toString())) + ((b_2 += -2 / -2) != 3 % "c"):
                ;
                break;
            }
        }
        var bar = f5(arguments_1);
    }
    var yield_1 = f1(..."" + undefined, 0 === 1 ? a : b, -1);
    function f6(b_1) {
        {
            return "c";
        }
        [ (c = 1 + c, ([ , 0 ][1] - -4 === -0 - [ , 0 ][1]) > (-2 >>> NaN <= 3 - "bar")), (c = c + 1) + [ (c = 1 + c, 
        b_1 && (b_1.foo += ((0, 22) >> ("b" | false)) / (("c" ^ 3) != 24..toString() - ""))) ].undefined, --b + (b = a) ];
    }
    var foo_2 = f6();
}

var b_1 = f0(b = a);

console.log(null, a, b, c, Infinity, NaN, undefined);

// uglified code
// (beautified)
var _calls_ = 10, a = 100, b = 10, c = 0;

async function f0(a, n) {
    var o, f = void 0;
    for await (o of [ (c = 1 + c, 0) ]) {
        c = 1 + c;
    }
    f = void 0, function() {
        switch (!1) {
          case "3function" % (this >>> -0) - (((!0)[c = 1 + (c = 1 + (c = 1 + c)), 
            (!0)["function" == typeof f7 && 0 <= --_calls_ && f7({})] += 0 * (-0 !== (2 === [ , 0 ].length && "b"))] = 25 != this) <= !0):
            break;

          case c = 1 + (c = 1 + c), 5 + (!1 <= (22 == (2 === [ , 0 ].length))):
          case c = 1 + c, 2047 + (NaN != (f += 1)):
        }
    }();
}

var b_1 = f0(b = a);

console.log(null, a, b, c, 1 / 0, NaN, void 0);

original result:
null 100 100 7 Infinity NaN undefined

uglified result:
null 100 100 1 Infinity NaN undefined

// reduced test case (output will differ)

// (beautified)
async function f0() {
    async function f3() {
        var expr2 = [];
        for await (var key2 of expr2) {}
    }
    f3();
    console.log();
}

f0();

console.log(undefined);
// output: 
// undefined
// 
// minify: undefined
// 
// 
// options: {
//   "compress": {
//     "passes": 1000000,
//     "sequences": 1000000,
//     "unsafe": true,
//     "unsafe_Function": true,
//     "unsafe_math": true,
//     "unsafe_proto": true,
//     "unsafe_regexp": true
//   },
//   "output": {
//     "v8": true
//   },
//   "validate": true
// }

minify(options):
{
  "compress": {
    "passes": 1000000,
    "sequences": 1000000,
    "unsafe": true,
    "unsafe_Function": true,
    "unsafe_math": true,
    "unsafe_proto": true,
    "unsafe_regexp": true
  },
  "output": {
    "v8": true
  }
}

Suspicious compress options:
  awaits
  collapse_vars
  evaluate
  inline
  passes
  reduce_vars
  unsafe
  unused