ufuzz failure

[alexlamsl]

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

function f0(async) {
    function f1(arguments) {
        function f2(foo_1, c_2) {
            {
            }
            if (c = 1 + c, (-4 & [ , 0 ].length === 2) < [] << 2 ^ (25, 2) * (4, 
            "b")) {
                c = 1 + c, ("a" | -5) % (24..toString() >= -0) % ((1 >= {}) >> ("" ^ 4));
            } else {
                c = 1 + c, ([] > Infinity) - ("c" >= this) ^ (c = c + 1, undefined, 
                "function", {});
            }
            c = 1 + c, "foo" < 0 == -3 / Infinity ^ !3 < ("object" ^ []);
        }
        var a_2 = f2((23..toString() & /[a2][^e]+$/) + (-3 && "number") || ({} ^ 23..toString() || (c = c + 1, 
        "number")), ("function" + undefined >= 2 << 1) - ("foo" >> this & 23..toString() === -0), typeof f4 == "function" && --_calls_ >= 0 && f4((c = 1 + c, 
        (("foo" !== -1) << (-4 && [ , 0 ][1])) * ((async && (async.b += [] >> "c")) | 4 > -4))));
        function f3() {
            switch (c = 1 + c, "number" << 5 << (false | [ , 0 ][1]) === (arguments && (arguments.done = (c = c + 1, 
            23..toString()) ^ (null && "a")))) {
              case c = 1 + c, arguments && (arguments[(c = c + 1) + (0 === 1 ? a : b)] += (22 == [] === (arguments && (arguments[c = 1 + c, 
                (async && (async.static >>>= /[a2][^e]+$/ || false)) !== ("undefined" !== 4) == 2 - "object" > -3 - {}] -= null || 22))) >> ("foo" && "b" && (false || "object"))):
                ;
                break;

              case c = 1 + c, ("a" % 5 ^ (-3 | "b")) + ((async && (async[c = 1 + c, 
                ("function" == false) >= ("undefined" ^ "b") ^ 3 + "a" >= {} >> "b"] += -3 == 1)) & (-4 || 2)):
                ;

              default:
                ;

              case c = 1 + c, ("foo" && this) * (38..toString() < true) % ((-0 !== 3) << (/[a2][^e]+$/ ^ "a")):
                ;
                break;
            }
        }
        var bar_1 = f3("object", (c = c + 1) + {
            undefined: (c = 1 + c, ((c = c + 1, "a") == (undefined & "undefined")) > (arguments && (arguments[{
                set: (c = 1 + c, !(-"a" && undefined << -0)),
                static: (c = 1 + c, (async && (async[a++ + [ (c = 1 + c, ~((/[a2][^e]+$/ | undefined) == 1 >> 38..toString())) ][c = 1 + c, 
                ("bar" >= false & (arguments && (arguments[c = 1 + c, ("number" || "function" || -3 | 1) >= (-2 <= -3 == -4 >= -3)] += "number" % "a"))) >= (arguments && (arguments.value -= 5 | []) && Infinity != -0)]] = Infinity < "a" != "number" > undefined)) + ((-3 === 3) << false * Infinity)),
                Infinity: (c = 1 + c, (-4 >> 23..toString() >= undefined * (-42n).toString()) + (("number" == 22) + ([ , 0 ].length === 2) % 24..toString()))
            }.in] = (0 >> 4) / (Infinity >>> "a"))))
        }[{
            3: (c = 1 + c, a_2 && (a_2[a--] = (/[a2][^e]+$/ < -0 ^ undefined << Infinity) < ("a" != -2 == (a_2 && (a_2[c = 1 + c, 
            ~(3 << 4 << ("undefined" === 38..toString()))] = 1 && 5)))))
        }.length]);
    }
    var await_1 = f1((c = c + 1) + (typeof f5 == "function" && --_calls_ >= 0 && f5(this)));
    function f4(await_2) {
        {
            var let_2 = function f5(foo = NaN) {
                L23432: for (var brake8 = 5; (c = 1 + c, (false % NaN == /[a2][^e]+$/ - "b") + +(NaN / {})) && brake8 > 0; --brake8) {
                    c = 1 + c, (await_2 && (await_2[c = 1 + c, ((async && (async[c = 1 + c, 
                    (await_1 && (await_1[c = 1 + c, (foo = 5 - undefined >= 24..toString() + "") !== ("" ^ "bar") * (-3 ^ "number")] += "" << 24..toString()) && ("undefined", 
                    24..toString())) * ("b" === "b" && 25 > 5)] = NaN == "b")) == ([ 3n ][0] > 2) >> 2) / ("" >> /[a2][^e]+$/ ^ (null || [ , 0 ].length === 2))] += 38..toString() / "number")) + (await_2 += 38..toString() != /[a2][^e]+$/) - (0 / 0, 
                    await_2 = -2 ^ "function");
                }
                var arguments_1;
                {
                    var expr11 = (c = 1 + c, c = c + 1, -5 != undefined | [] & 22);
                    for (var key11 in expr11) {
                        c = 1 + c;
                        const async = expr11[key11];
                        c = 1 + c, (async && (async.done |= (c = c + 1, "") ^ 25 != 22)) ^ void "function" != 23..toString() - /[a2][^e]+$/;
                    }
                }
            }(23..toString());
        }
    }
}

var yield = f0([ a--, !(("foo" <= []) - ("bar" || [])), --b + a ]);

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

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

function f0(n) {
    !function(arguments) {
        if (0 <= --_calls_) {
            for (var n in c = 1 + c, e && (e.b += 0), c = 1 + (c = 1 + c), c += 1, 
            1) {
                c = 1 + c;
                var e = 1[n];
                c = 1 + c, e && (e.done |= !0 ^ (c += 1, ""));
            }
        }
        c = 1 + c, (-4 & 2 === [ , 0 ].length) < 0 ^ NaN ? c = 1 + c : (c = 1 + c, 
        c += 1);
        var t = void (c = 1 + c);
        !function() {
            switch (c = 1 + c, 0 === (arguments && (arguments.done = null ^ (c += 1, 
            "23")))) {
              case c = 1 + c, arguments && (arguments[(c += 1) + b] += (!1 === (arguments && (arguments[c = 1 + c, 
                !0 !== (e && (e.static >>>= /[a2][^e]+$/)) == 0] -= 22))) >> "object"):
                break;

              case c = 1 + c, (-4 & (e && (e[c = 1 + c, 1] += !1))) - 3:
              default:
              case c = 1 + c, !1 * this % 1:
            }
        }("object", (c += 1) + {
            undefined: (c = 1 + c, (0 == (c += 1, "a")) > (arguments && (arguments[{
                set: !0,
                static: (c = 1 + (c = 1 + c), (e && (e[a++ + [ -2 ][c = 1 + (c = 1 + c), 
                (!1 & (arguments && (arguments[c = 1 + c, !1] += NaN))) >= (arguments && (arguments.value -= 5) && !0)]] = !1)) + 0),
                Infinity: (c = 1 + c, !1 + (2 === [ , 0 ].length) % "24" + (void 0 * ("" + -42n) <= -1))
            }.in] = NaN)))
        }[{
            3: (c = 1 + c, t && (t[a--] = 0 < (1 == (t && (t[c = 1 + c, -49] = 5)))))
        }.length]);
    }((c += 1) + ("function" == typeof f5 && 0 <= --_calls_ && f5(this)));
}

var yield = f0([ a--, !0, --b + a ]);

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

original result:
null 100 9 27 Infinity NaN undefined

uglified result:
null 99 9 23 Infinity NaN undefined

// reduced test case (output will differ)

// (beautified)
function f0() {
    var a_2 = f4 && f4();
    async;
    function f4() {
        var let_2 = function f5() {
            for (var brake8 = 5; 0; 0) {
                async;
            }
            for (var key11 in 0) {
                const async = key11;
                async && async.done;
            }
        }();
    }
}

f0();
// output: ReferenceError: async is not defined
// minify: 
// 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:
  conditionals
  dead_code
  evaluate
  inline
  loops
  passes
  reduce_funcs
  reduce_vars
  sequences
  side_effects
  unsafe
  unused
  varify