v3.13.10

fixes #5036

bin/uglifyjs

@@ -344,9 +344,9 @@ function run() {
                     var list = annotations[node.start.file];
                     var pure = list[node.start.pos];
                     if (!pure) {
-                        var pos = node.start.parens;
-                        if (pos) for (var i = 0; !pure && i < pos.length; i++) {
-                            pure = list[pos[i]];
+                        var tokens = node.start.parens;
+                        if (tokens) for (var i = 0; !pure && i < tokens.length; i++) {
+                            pure = list[tokens[i].pos];
                         }
                     }
                     if (pure) node.pure = pure;

lib/ast.js

@@ -56,35 +56,31 @@ function DEFNODE(type, props, methods, base) {
         code.push("this.", prop, "=props.", prop, ";");
     });
     code.push("}");
-    var proto = base && new base;
-    if (proto && proto.initialize || methods && methods.initialize) code.push("this.initialize();");
-    code.push("}");
+    var proto = Object.create(base && base.prototype);
+    if (methods.initialize || proto.initialize) code.push("this.initialize();");
+    code.push("};");
     var ctor = new Function(code.join(""))();
-    if (proto) {
-        ctor.prototype = proto;
-        ctor.BASE = base;
-    }
-    if (base) base.SUBCLASSES.push(ctor);
+    ctor.prototype = proto;
     ctor.prototype.CTOR = ctor;
-    ctor.PROPS = props || null;
-    ctor.SELF_PROPS = self_props;
-    ctor.SUBCLASSES = [];
-    if (type) {
-        ctor.prototype.TYPE = ctor.TYPE = type;
-    }
-    if (methods) for (var name in methods) if (HOP(methods, name)) {
-        if (/^\$/.test(name)) {
-            ctor[name.substr(1)] = methods[name];
-        } else {
-            ctor.prototype[name] = methods[name];
-        }
+    ctor.prototype.TYPE = ctor.TYPE = type;
+    if (base) {
+        ctor.BASE = base;
+        base.SUBCLASSES.push(ctor);
     }
     ctor.DEFMETHOD = function(name, method) {
         this.prototype[name] = method;
     };
-    if (typeof exports !== "undefined") {
-        exports["AST_" + type] = ctor;
+    ctor.PROPS = props;
+    ctor.SELF_PROPS = self_props;
+    ctor.SUBCLASSES = [];
+    for (var name in methods) if (HOP(methods, name)) {
+        if (/^\$/.test(name)) {
+            ctor[name.substr(1)] = methods[name];
+        } else {
+            ctor.DEFMETHOD(name, methods[name]);
+        }
     }
+    if (typeof exports !== "undefined") exports["AST_" + type] = ctor;
     return ctor;
 }
 

lib/compress.js

@@ -108,6 +108,7 @@ function Compressor(options, false_by_default) {
         unsafe_undefined: false,
         unused          : !false_by_default,
         varify          : !false_by_default,
+        webkit          : false,
         yields          : !false_by_default,
     }, true);
     var evaluate = this.options["evaluate"];
@@ -606,7 +607,11 @@ merge(Compressor.prototype, {
             var safe = tw.safe_ids[def.id];
             if (!HOP(tw.safe_ids, def.id)) {
                 if (!safe) return false;
-                if (safe.read && def.scope.resolve() !== tw.find_parent(AST_Scope)) return false;
+                if (safe.read) {
+                    var scope = tw.find_parent(AST_BlockScope);
+                    if (scope instanceof AST_Class) return false;
+                    if (def.scope.resolve() !== scope.resolve()) return false;
+                }
                 safe.assign = safe.assign && safe.assign !== tw.safe_ids ? true : tw.safe_ids;
             }
             if (def.fixed != null && safe.read) {
@@ -1008,6 +1013,11 @@ merge(Compressor.prototype, {
                 reset_def(tw, compressor, def);
             });
             if (node.extends) node.extends.walk(tw);
+            var props = node.properties.filter(function(prop) {
+                reset_flags(prop);
+                if (prop.key instanceof AST_Node) prop.key.walk(tw);
+                return prop.value;
+            });
             if (node.name) {
                 var d = node.name.definition();
                 var parent = tw.parent();
@@ -1024,11 +1034,7 @@ merge(Compressor.prototype, {
                     d.fixed = false;
                 }
             }
-            node.properties.filter(function(prop) {
-                reset_flags(prop);
-                if (prop.key instanceof AST_Node) prop.key.walk(tw);
-                return prop.value;
-            }).forEach(function(prop) {
+            props.forEach(function(prop) {
                 if (!prop.static || prop instanceof AST_ClassField && prop.value.contains_this()) {
                     push(tw);
                     prop.value.walk(tw);
@@ -1506,7 +1512,7 @@ merge(Compressor.prototype, {
     function is_lhs_read_only(lhs, compressor) {
         if (lhs instanceof AST_ObjectIdentity) return true;
         if (lhs instanceof AST_PropAccess) {
-            if (lhs.property == "__proto__") return true;
+            if (lhs.property === "__proto__") return true;
             lhs = lhs.expression;
             if (lhs instanceof AST_SymbolRef) {
                 if (lhs.is_immutable()) return false;
@@ -1710,6 +1716,15 @@ merge(Compressor.prototype, {
         return stat instanceof AST_LambdaDefinition;
     }
 
+    function is_last_statement(body, stat) {
+        var index = body.lastIndexOf(stat);
+        if (index < 0) return false;
+        while (++index < body.length) {
+            if (!is_declaration(body[index], true)) return false;
+        }
+        return true;
+    }
+
     function tighten_body(statements, compressor) {
         var in_loop, in_try, scope;
         find_loop_scope_try();
@@ -1804,10 +1819,7 @@ merge(Compressor.prototype, {
                         return node;
                     }
                     if (is_lhs(node, parent)) {
-                        if (value_def && !hit_rhs) {
-                            assign_used = true;
-                            replaced++;
-                        }
+                        if (value_def && !hit_rhs) assign_used = true;
                         return node;
                     } else if (value_def) {
                         if (stop_if_hit && assign_pos == 0) assign_pos = remaining - replaced;
@@ -1932,10 +1944,9 @@ merge(Compressor.prototype, {
                     }
                 }
                 // Replace variable when found
-                if (node instanceof AST_SymbolRef
-                    && node.name == def.name) {
-                    if (!--replaced) abort = true;
+                if (node instanceof AST_SymbolRef && node.definition() === def) {
                     if (is_lhs(node, multi_replacer.parent())) return node;
+                    if (!--replaced) abort = true;
                     var ref = rvalue.clone();
                     ref.scope = node.scope;
                     ref.reference();
@@ -2011,7 +2022,7 @@ merge(Compressor.prototype, {
                         statements[i].transform(scanner);
                     }
                     if (value_def) {
-                        if (!replaced || remaining > replaced) {
+                        if (!replaced || remaining > replaced + assign_used) {
                             candidates.push(hit_stack);
                             force_single = true;
                             continue;
@@ -3164,15 +3175,6 @@ merge(Compressor.prototype, {
                 return !value || value instanceof AST_UnaryPrefix && value.operator == "void";
             }
 
-            function is_last_statement(body, stat) {
-                var index = body.lastIndexOf(stat);
-                if (index < 0) return false;
-                while (++index < body.length) {
-                    if (!is_declaration(body[index], true)) return false;
-                }
-                return true;
-            }
-
             function last_of(predicate) {
                 var block = self, stat, level = 0;
                 do {
@@ -3838,7 +3840,7 @@ merge(Compressor.prototype, {
         def(AST_Object, function(compressor, force) {
             return is_strict(compressor, force) && !all(this.properties, function(prop) {
                 if (!(prop instanceof AST_ObjectKeyVal)) return false;
-                return !(prop.key == "__proto__" && prop.value._dot_throw(compressor, force));
+                return !(prop.key === "__proto__" && prop.value._dot_throw(compressor, force));
             });
         });
         def(AST_ObjectIdentity, function(compressor, force) {
@@ -5271,7 +5273,7 @@ merge(Compressor.prototype, {
                 || any(this.body, compressor);
         });
         def(AST_SymbolRef, function(compressor) {
-            return !this.is_declared(compressor);
+            return !this.is_declared(compressor) || !can_drop_symbol(this, compressor);
         });
         def(AST_Template, function(compressor) {
             if (any(this.expressions, compressor)) return true;
@@ -5856,6 +5858,7 @@ merge(Compressor.prototype, {
                 if (head_refs.start.block !== tail_refs.start.block
                     || !mergeable(head_refs, tail_refs)
                     || (head_refs.start.loop || !same_scope(def)) && !mergeable(tail_refs, head_refs)
+                    || compressor.option("webkit") && is_funarg(def) !== is_funarg(tail.definition)
                     || !all(tail_refs, function(sym) {
                         return sym.scope.find_variable(def.name) === def;
                     })) {
@@ -6042,27 +6045,16 @@ merge(Compressor.prototype, {
             function compose(child, level, find) {
                 var parent = compressor.parent(level);
                 if (!parent) return find;
-                if (parent instanceof AST_DestructuredKeyVal) {
-                    var destructured = compressor.parent(level + 1);
-                    if (parent.key === child) {
-                        var fn = compressor.parent(level + 2);
-                        if (fn instanceof AST_Lambda) {
-                            return compose(fn, level + 3, fn.argnames.indexOf(destructured) >= 0 ? function(name) {
-                                var def = find(name);
-                                if (def) return def;
-                                def = fn.variables.get(name);
-                                if (def) {
-                                    var sym = def.orig[0];
-                                    if (sym instanceof AST_SymbolFunarg || sym instanceof AST_SymbolLambda) return def;
-                                }
-                            } : function(name) {
-                                return find(name) || fn.variables.get(name);
-                            });
-                        }
+                var in_arg = parent instanceof AST_Lambda && member(child, parent.argnames);
+                return compose(parent, level + 1, in_arg ? function(name) {
+                    var def = find(name);
+                    if (def) return def;
+                    def = parent.variables.get(name);
+                    if (def) {
+                        var sym = def.orig[0];
+                        if (sym instanceof AST_SymbolFunarg || sym instanceof AST_SymbolLambda) return def;
                     }
-                    return compose(destructured, level + 2, find);
-                }
-                return compose(parent, level + 1, parent.variables ? function(name) {
+                } : parent.variables ? function(name) {
                     return find(name) || parent.variables.get(name);
                 } : find);
             }
@@ -6570,10 +6562,23 @@ merge(Compressor.prototype, {
                         if (def.orig.length > 1) return null;
                         if (def.assignments > 0) return false;
                         if (def.name == name) return def;
-                        if (name == "await" && is_async(fn)) return false;
-                        if (name == "yield" && is_generator(fn)) return false;
+                        var forbidden;
+                        switch (name) {
+                          case "await":
+                            forbidden = is_async;
+                            break;
+                          case "yield":
+                            forbidden = is_generator;
+                            break;
+                        }
                         return all(def.references, function(ref) {
-                            return ref.scope.find_variable(name) === sym;
+                            var scope = ref.scope;
+                            if (scope.find_variable(name) !== sym) return false;
+                            if (forbidden) do {
+                                scope = scope.resolve();
+                                if (forbidden(scope)) return false;
+                            } while (scope !== fn && (scope = scope.parent_scope));
+                            return true;
                         }) && def;
                     }
 
@@ -6734,7 +6739,7 @@ merge(Compressor.prototype, {
                 return insert_statements(body, node, in_list);
             }
             if (node instanceof AST_Import) {
-                if (node.properties && node.properties == 0) node.properties = null;
+                if (node.properties && node.properties.length == 0) node.properties = null;
                 return node;
             }
             if (node instanceof AST_Sequence) {
@@ -7603,11 +7608,22 @@ merge(Compressor.prototype, {
                             node.body = body;
                         }
                     } else if (body instanceof AST_Sequence) {
-                        var tail = body.tail_node();
-                        if (tail instanceof AST_Await && is_primitive(compressor, tail.expression)) {
-                            tail = tail.expression.drop_side_effect_free(compressor);
-                            body.expressions.pop();
-                            if (tail) body.expressions.push(tail);
+                        var exprs = body.expressions;
+                        for (var i = exprs.length; --i >= 0;) {
+                            var tail = exprs[i];
+                            if (!(tail instanceof AST_Await)) break;
+                            if (!is_primitive(compressor, tail.expression)) break;
+                            if (exprs[i] = tail.expression.drop_side_effect_free(compressor)) break;
+                        }
+                        switch (i) {
+                          case -1:
+                            return make_node(AST_EmptyStatement, node);
+                          case 0:
+                            node.body = exprs[0];
+                            break;
+                          default:
+                            exprs.length = i + 1;
+                            break;
                         }
                     }
                     return node;
@@ -7691,24 +7707,24 @@ merge(Compressor.prototype, {
             }
             return self;
         });
-        def(AST_Class, function(compressor, first_in_statement) {
+        function drop_class(self, compressor, first_in_statement) {
             var exprs = [], values = [];
-            var props = this.properties;
+            var props = self.properties;
             for (var i = 0; i < props.length; i++) {
                 var prop = props[i];
                 if (prop.key instanceof AST_Node) exprs.push(prop.key);
                 if (prop.static && prop.value
                     && prop instanceof AST_ClassField
                     && prop.value.has_side_effects(compressor)) {
-                    if (prop.value.contains_this()) return this;
+                    if (prop.value.contains_this()) return self;
                     values.push(prop.value);
                 }
             }
-            var base = this.extends;
+            var base = self.extends;
             if (base) {
                 if (base instanceof AST_SymbolRef) base = base.fixed_value();
                 base = !safe_for_extends(base);
-                if (!base) exprs.unshift(this.extends);
+                if (!base) exprs.unshift(self.extends);
             }
             exprs = trim(exprs, compressor, first_in_statement);
             if (exprs) first_in_statement = false;
@@ -7718,26 +7734,32 @@ merge(Compressor.prototype, {
                 exprs = [];
             }
             if (base) {
-                var node = to_class_expr(this, true);
+                var node = to_class_expr(self, true);
                 node.properties = [];
-                if (exprs.length) node.properties.push(make_node(AST_ClassMethod, this, {
-                    key: make_sequence(this, exprs),
-                    value: make_node(AST_Function, this, {
+                if (exprs.length) node.properties.push(make_node(AST_ClassMethod, self, {
+                    key: make_sequence(self, exprs),
+                    value: make_node(AST_Function, self, {
                         argnames: [],
                         body: [],
                     }).init_vars(node),
                 }));
                 exprs = [ node ];
             }
-            if (values) exprs.push(make_node(AST_Call, this, {
-                expression: make_node(AST_Arrow, this, {
+            if (values) exprs.push(make_node(AST_Call, self, {
+                expression: make_node(AST_Arrow, self, {
                     argnames: [],
                     body: [],
-                    value: make_sequence(this, values),
-                }).init_vars(this.parent_scope),
+                    value: make_sequence(self, values),
+                }).init_vars(self.parent_scope),
                 args: [],
             }));
-            return make_sequence(this, exprs);
+            return make_sequence(self, exprs);
+        }
+        def(AST_ClassExpression, function(compressor, first_in_statement) {
+            var self = this;
+            var name = self.name;
+            if (name && name.fixed_value() !== self && name.definition().references.length > 0) return self;
+            return drop_class(self, compressor, first_in_statement);
         });
         def(AST_Conditional, function(compressor) {
             var consequent = this.consequent.drop_side_effect_free(compressor);
@@ -7778,6 +7800,9 @@ merge(Compressor.prototype, {
             return exprs.length == 0 ? null : make_sequence(this, exprs);
         });
         def(AST_Constant, return_null);
+        def(AST_DefClass, function(compressor, first_in_statement) {
+            return drop_class(this, compressor, first_in_statement);
+        });
         def(AST_Dot, function(compressor, first_in_statement) {
             var expr = this.expression;
             if (!this.optional && expr.may_throw_on_access(compressor)) return this;
@@ -8104,10 +8129,6 @@ merge(Compressor.prototype, {
                 cond = self.condition.is_truthy() || self.condition.evaluate(compressor, true);
             } else if (cond) {
                 self.condition = null;
-            } else if (!compressor.option("dead_code")) {
-                var orig = self.condition;
-                self.condition = make_node_from_constant(cond, self.condition);
-                self.condition = best_of_expression(self.condition.transform(compressor), orig);
             }
             if (!cond) {
                 if (compressor.option("dead_code")) {
@@ -8214,40 +8235,88 @@ merge(Compressor.prototype, {
         }
     }
 
+    function fuzzy_eval(compressor, node, nullish) {
+        if (node.truthy) return true;
+        if (node.falsy && !nullish) return false;
+        if (node.is_truthy()) return true;
+        return node.evaluate(compressor, true);
+    }
+
+    function mark_duplicate_condition(compressor, node) {
+        for (var level = 0, child = compressor.self(), parent; ; child = parent) {
+            parent = compressor.parent(level++);
+            if (parent instanceof AST_Binary) {
+                var op = parent.operator;
+                if (!lazy_op[op]) return;
+                var left = parent.left;
+                if (left === child) continue;
+                if (node.equivalent_to(left)) node[op == "&&" ? "truthy" : "falsy"] = true;
+            } else if (parent instanceof AST_Conditional) {
+                var cond = parent.condition;
+                if (cond === child) continue;
+                if (node.equivalent_to(cond)) switch (child) {
+                  case parent.consequent:
+                    node.truthy = true;
+                    break;
+                  case parent.alternative:
+                    node.falsy = true;
+                    break;
+                }
+            } else if (parent instanceof AST_Exit) {
+                break;
+            } else if (parent instanceof AST_If) {
+                break;
+            } else if (parent instanceof AST_Sequence) {
+                if (parent.expressions[0] === child) continue;
+            } else if (parent instanceof AST_SimpleStatement) {
+                break;
+            }
+            return;
+        }
+        while (true) {
+            child = parent;
+            parent = compressor.parent(level++);
+            if (parent instanceof AST_BlockStatement) {
+                if (parent.body[0] === child) continue;
+            } else if (parent instanceof AST_If) {
+                var cond = parent.condition;
+                if (cond === child) continue;
+                if (node.equivalent_to(cond)) switch (child) {
+                  case parent.body:
+                    node.truthy = true;
+                    break;
+                  case parent.alternative:
+                    node.falsy = true;
+                    break;
+                }
+            }
+            return;
+        }
+    }
+
     OPT(AST_If, function(self, compressor) {
         if (is_empty(self.alternative)) self.alternative = null;
 
         if (!compressor.option("conditionals")) return self;
+        if (compressor.option("booleans") && !self.condition.has_side_effects(compressor)) {
+            mark_duplicate_condition(compressor, self.condition);
+        }
         // if condition can be statically determined, warn and drop
         // one of the blocks.  note, statically determined implies
         // “has no side effects”; also it doesn't work for cases like
         // `x && true`, though it probably should.
-        var cond = self.condition.evaluate(compressor);
-        if (!compressor.option("dead_code") && !(cond instanceof AST_Node)) {
-            var orig = self.condition;
-            self.condition = make_node_from_constant(cond, orig);
-            self.condition = best_of_expression(self.condition.transform(compressor), orig);
-        }
         if (compressor.option("dead_code")) {
-            if (cond instanceof AST_Node) {
-                cond = self.condition.is_truthy() || self.condition.evaluate(compressor, true);
-            }
+            var cond = fuzzy_eval(compressor, self.condition);
             if (!cond) {
                 AST_Node.warn("Condition always false [{file}:{line},{col}]", self.condition.start);
-                var body = [
-                    make_node(AST_SimpleStatement, self.condition, {
-                        body: self.condition
-                    }),
-                ];
+                var body = [ make_node(AST_SimpleStatement, self.condition, { body: self.condition }) ];
                 extract_declarations_from_unreachable_code(compressor, self.body, body);
                 if (self.alternative) body.push(self.alternative);
                 return make_node(AST_BlockStatement, self, { body: body }).optimize(compressor);
             } else if (!(cond instanceof AST_Node)) {
                 AST_Node.warn("Condition always true [{file}:{line},{col}]", self.condition.start);
                 var body = [
-                    make_node(AST_SimpleStatement, self.condition, {
-                        body: self.condition
-                    }),
+                    make_node(AST_SimpleStatement, self.condition, { body: self.condition }),
                     self.body,
                 ];
                 if (self.alternative) extract_declarations_from_unreachable_code(compressor, self.alternative, body);
@@ -8271,9 +8340,7 @@ merge(Compressor.prototype, {
         var body_exprs = sequencesize(self.body, body, var_defs, refs);
         var alt_exprs = sequencesize(self.alternative, body, var_defs, refs);
         if (body_exprs && alt_exprs) {
-            if (var_defs.length > 0) body.push(make_node(AST_Var, self, {
-                definitions: var_defs
-            }));
+            if (var_defs.length > 0) body.push(make_node(AST_Var, self, { definitions: var_defs }));
             if (body_exprs.length == 0) {
                 body.push(make_node(AST_SimpleStatement, self.condition, {
                     body: alt_exprs.length > 0 ? make_node(AST_Binary, self, {
@@ -8420,22 +8487,14 @@ merge(Compressor.prototype, {
 
     OPT(AST_Switch, function(self, compressor) {
         if (!compressor.option("switches")) return self;
-        var branch;
-        var value = self.expression.evaluate(compressor);
-        if (!(value instanceof AST_Node)) {
-            var orig = self.expression;
-            self.expression = make_node_from_constant(value, orig);
-            self.expression = best_of_expression(self.expression.transform(compressor), orig);
-        }
         if (!compressor.option("dead_code")) return self;
-        if (value instanceof AST_Node) {
-            value = self.expression.evaluate(compressor, true);
-        }
-        var decl = [];
         var body = [];
+        var branch;
+        var decl = [];
         var default_branch;
         var exact_match;
-        for (var i = 0, len = self.body.length; i < len && !exact_match; i++) {
+        var side_effects = [];
+        for (var i = 0, len = self.body.length; i < len; i++) {
             branch = self.body[i];
             if (branch instanceof AST_Default) {
                 var prev = body[body.length - 1];
@@ -8445,33 +8504,61 @@ merge(Compressor.prototype, {
                 } else {
                     default_branch = branch;
                 }
-            } else if (!(value instanceof AST_Node)) {
-                var exp = branch.expression.evaluate(compressor);
-                if (!(exp instanceof AST_Node) && exp !== value) {
+            } else {
+                var exp = branch.expression;
+                var equals = make_node(AST_Binary, self, {
+                    operator: "===",
+                    left: self.expression,
+                    right: exp,
+                }).evaluate(compressor, true);
+                if (!equals) {
+                    if (exp.has_side_effects(compressor)) side_effects.push(exp);
                     eliminate_branch(branch, body[body.length - 1]);
                     continue;
                 }
-                if (exp instanceof AST_Node) exp = branch.expression.evaluate(compressor, true);
-                if (exp === value) {
-                    exact_match = branch;
+                if (!(equals instanceof AST_Node)) {
                     if (default_branch) {
                         var default_index = body.indexOf(default_branch);
                         body.splice(default_index, 1);
                         eliminate_branch(default_branch, body[default_index - 1]);
                         default_branch = null;
                     }
+                    if (exp.has_side_effects(compressor)) {
+                        exact_match = branch;
+                    } else {
+                        default_branch = branch = make_node(AST_Default, branch, branch);
+                    }
+                    while (++i < len) eliminate_branch(self.body[i], branch);
                 }
             }
-            if (aborts(branch)) {
+            if (i + 1 >= len || aborts(branch)) {
                 var prev = body[body.length - 1];
-                if (aborts(prev) && prev.body.length == branch.body.length
-                    && make_node(AST_BlockStatement, prev, prev).equivalent_to(make_node(AST_BlockStatement, branch, branch))) {
-                    prev.body = [];
+                var statements = branch.body;
+                if (aborts(prev)) switch (prev.body.length - statements.length) {
+                  case 1:
+                    var stat = prev.body[prev.body.length - 1];
+                    if (!is_break(stat, compressor)) break;
+                    statements = statements.concat(stat);
+                  case 0:
+                    var prev_block = make_node(AST_BlockStatement, prev, prev);
+                    var next_block = make_node(AST_BlockStatement, branch, { body: statements });
+                    if (prev_block.equivalent_to(next_block)) prev.body = [];
                 }
             }
+            if (side_effects.length) {
+                if (branch instanceof AST_Default) {
+                    body.push(make_node(AST_Case, self, { expression: make_sequence(self, side_effects), body: [] }));
+                } else {
+                    side_effects.push(branch.expression);
+                    branch.expression = make_sequence(self, side_effects);
+                }
+                side_effects = [];
+            }
             body.push(branch);
         }
-        while (i < len) eliminate_branch(self.body[i++], body[body.length - 1]);
+        if (side_effects.length && !exact_match) {
+            body.push(make_node(AST_Case, self, { expression: make_sequence(self, side_effects), body: [] }));
+        }
         while (branch = body[body.length - 1]) {
             var stat = branch.body[branch.body.length - 1];
             if (is_break(stat, compressor)) branch.body.pop();
@@ -8488,12 +8575,24 @@ merge(Compressor.prototype, {
             eliminate_branch(branch);
             if (body.pop() === default_branch) default_branch = null;
         }
-        if (body.length == 0) {
-            return make_node(AST_BlockStatement, self, {
-                body: decl.concat(make_node(AST_SimpleStatement, self.expression, {
-                    body: self.expression
-                }))
-            }).optimize(compressor);
+        if (!branch) {
+            decl.push(make_node(AST_SimpleStatement, self.expression, { body: self.expression }));
+            if (side_effects.length) decl.push(make_node(AST_SimpleStatement, self, {
+                body: make_sequence(self, side_effects),
+            }));
+            return make_node(AST_BlockStatement, self, { body: decl }).optimize(compressor);
+        }
+        if (branch === default_branch) while (branch = body[body.length - 2]) {
+            if (branch instanceof AST_Default) break;
+            if (!has_declarations_only(branch)) break;
+            var exp = branch.expression;
+            if (exp.has_side_effects(compressor)) {
+                var prev = body[body.length - 3];
+                if (prev && !aborts(prev)) break;
+                default_branch.body.unshift(make_node(AST_SimpleStatement, self, { body: exp }));
+            }
+            eliminate_branch(branch);
+            body.splice(-2, 1);
         }
         body[0].body = decl.concat(body[0].body);
         self.body = body;
@@ -9774,7 +9873,7 @@ merge(Compressor.prototype, {
     OPT(AST_Sequence, function(self, compressor) {
         var expressions = filter_for_side_effects();
         var end = expressions.length - 1;
-        merge_conditional_assignments();
+        merge_assignments();
         trim_right_for_undefined();
         if (end == 0) {
             self = maintain_this_binding(compressor, compressor.parent(), compressor.self(), expressions[0]);
@@ -9811,19 +9910,33 @@ merge(Compressor.prototype, {
             }
         }
 
-        function merge_conditional_assignments() {
-            if (!compressor.option("conditionals")) return;
+        function is_simple_assign(node) {
+            return node instanceof AST_Assign
+                && node.operator == "="
+                && node.left instanceof AST_SymbolRef
+                && node.left.definition();
+        }
+
+        function merge_assignments() {
             for (var i = 1; i < end; i++) {
-                var assign = expressions[i - 1];
-                if (!(assign instanceof AST_Assign)) continue;
-                if (assign.operator != "=") continue;
-                if (!(assign.left instanceof AST_SymbolRef)) continue;
-                var def = assign.left.definition();
-                var cond = to_conditional_assignment(compressor, def, assign.right, expressions[i]);
-                if (!cond) continue;
-                assign.right = cond;
-                expressions.splice(i, 1);
-                end--;
+                var prev = expressions[i - 1];
+                var def = is_simple_assign(prev);
+                if (!def) continue;
+                var expr = expressions[i];
+                if (compressor.option("conditionals")) {
+                    var cond = to_conditional_assignment(compressor, def, prev.right, expr);
+                    if (cond) {
+                        prev.right = cond;
+                        expressions.splice(i--, 1);
+                        end--;
+                        continue;
+                    }
+                }
+                if (compressor.option("dead_code")
+                    && is_simple_assign(expr) === def
+                    && expr.right.is_constant_expression(def.scope.resolve())) {
+                    expressions[--i] = prev.right;
+                }
             }
         }
     });
@@ -10185,7 +10298,18 @@ merge(Compressor.prototype, {
             }
             break;
         }
-        var in_bool = compressor.option("booleans") && compressor.in_boolean_context();
+        var in_bool = false;
+        var parent = compressor.parent();
+        if (compressor.option("booleans")) {
+            var lhs = self.left;
+            if (lazy_op[self.operator] && !lhs.has_side_effects(compressor)) {
+                if (lhs.equivalent_to(self.right)) {
+                    return maintain_this_binding(compressor, parent, compressor.self(), lhs).optimize(compressor);
+                }
+                mark_duplicate_condition(compressor, lhs);
+            }
+            in_bool = compressor.in_boolean_context();
+        }
         if (in_bool) switch (self.operator) {
           case "+":
             var ll = self.left.evaluate(compressor);
@@ -10219,7 +10343,6 @@ merge(Compressor.prototype, {
             }
             break;
         }
-        var parent = compressor.parent();
         if (compressor.option("comparisons") && self.is_boolean(compressor)) {
             if (!(parent instanceof AST_Binary) || parent instanceof AST_Assign) {
                 var negated = best_of(compressor, self, make_node(AST_UnaryPrefix, self, {
@@ -10277,7 +10400,7 @@ merge(Compressor.prototype, {
             var associative = true;
             switch (self.operator) {
               case "&&":
-                var ll = fuzzy_eval(self.left);
+                var ll = fuzzy_eval(compressor, self.left);
                 if (!ll) {
                     AST_Node.warn("Condition left of && always false [{file}:{line},{col}]", self.start);
                     return maintain_this_binding(compressor, parent, compressor.self(), self.left).optimize(compressor);
@@ -10313,7 +10436,7 @@ merge(Compressor.prototype, {
               case "??":
                 var nullish = true;
               case "||":
-                var ll = fuzzy_eval(self.left, nullish);
+                var ll = fuzzy_eval(compressor, self.left, nullish);
                 if (nullish ? ll == null : !ll) {
                     AST_Node.warn("Condition left of {operator} always {value} [{file}:{line},{col}]", {
                         operator: self.operator,
@@ -10696,13 +10819,6 @@ merge(Compressor.prototype, {
             });
         }
 
-        function fuzzy_eval(node, nullish) {
-            if (node.truthy) return true;
-            if (node.falsy && !nullish) return false;
-            if (node.is_truthy()) return true;
-            return node.evaluate(compressor, true);
-        }
-
         function is_indexFn(node) {
             return node.TYPE == "Call"
                 && node.expression instanceof AST_Dot
@@ -11055,9 +11171,11 @@ merge(Compressor.prototype, {
         });
         var scan_scope = new TreeWalker(function(node) {
             if (reachable) return true;
-            if (node instanceof AST_Scope && node !== self) {
-                var parent = scan_scope.parent();
-                if (parent instanceof AST_Call && parent.expression === node) return;
+            if (node instanceof AST_Lambda && node !== self) {
+                if (!(node.name || is_async(node) || is_generator(node))) {
+                    var parent = scan_scope.parent();
+                    if (parent instanceof AST_Call && parent.expression === node) return;
+                }
                 node.walk(find_ref);
                 return true;
             }
@@ -11113,28 +11231,36 @@ merge(Compressor.prototype, {
                             if (node instanceof AST_PropAccess) return true;
                             if (!found && node instanceof AST_SymbolRef && node.definition() === def) {
                                 if (in_try(level, parent)) return true;
-                                def.fixed = false;
                                 found = true;
                             }
                         })) break;
-                        if (found) return strip_assignment();
-                    } else if (parent instanceof AST_Exit) {
+                        if (!found) continue;
+                        return strip_assignment(def);
+                    }
+                    if (parent instanceof AST_Exit) {
                         if (!local) break;
                         if (in_try(level, parent)) break;
                         if (is_reachable(scope, [ def ])) break;
-                        def.fixed = false;
-                        return strip_assignment();
-                    } else if (parent instanceof AST_VarDef) {
+                        return strip_assignment(def);
+                    }
+                    if (parent instanceof AST_SimpleStatement) {
+                        if (!local) break;
+                        if (is_reachable(scope, [ def ])) break;
+                        var stat;
+                        do {
+                            stat = parent;
+                            parent = compressor.parent(level++);
+                            if (parent === scope && is_last_statement(parent.body, stat)) return strip_assignment(def);
+                        } while (is_tail_block(stat, parent));
+                        break;
+                    }
+                    if (parent instanceof AST_VarDef) {
                         if (!(parent.name instanceof AST_SymbolDeclaration)) continue;
                         if (parent.name.definition() !== def) continue;
                         if (in_try(level, parent)) break;
-                        def.fixed = false;
-                        return strip_assignment();
+                        return strip_assignment(def);
                     }
-                } while (parent instanceof AST_Binary && parent.right === node
-                    || parent instanceof AST_Conditional && parent.condition !== node
-                    || parent instanceof AST_Sequence && parent.tail_node() === node
-                    || parent instanceof AST_UnaryPrefix);
+                } while (is_tail(node, parent));
             }
         }
         if (compressor.option("sequences")) {
@@ -11179,26 +11305,55 @@ merge(Compressor.prototype, {
         }
         return try_evaluate(compressor, self);
 
+        function is_tail(node, parent) {
+            if (parent instanceof AST_Binary) {
+                return parent.right === node || parent.right.is_constant_expression(scope);
+            }
+            if (parent instanceof AST_Conditional) {
+                return parent.condition !== node
+                    || parent.consequent.is_constant_expression(scope)
+                        && parent.alternative.is_constant_expression(scope);
+            }
+            if (parent instanceof AST_Sequence) {
+                var exprs = parent.expressions;
+                var stop = exprs.indexOf(node);
+                if (stop < 0) return false;
+                for (var i = exprs.length; --i > stop;) {
+                    if (!exprs[i].is_constant_expression(scope)) return false;
+                }
+                return true;
+            }
+            if (parent instanceof AST_UnaryPrefix) return true;
+        }
+
+        function is_tail_block(stat, parent) {
+            if (parent instanceof AST_BlockStatement) return is_last_statement(parent.body, stat);
+            if (parent instanceof AST_Catch) return is_last_statement(parent.body, stat);
+            if (parent instanceof AST_Finally) return is_last_statement(parent.body, stat);
+            if (parent instanceof AST_If) return parent.body === stat || parent.alternative === stat;
+            if (parent instanceof AST_Try) return parent.bfinally ? parent.bfinally === stat : parent.bcatch === stat;
+        }
+
         function in_try(level, node) {
             var right = self.right;
             self.right = make_node(AST_Null, right);
             var may_throw = node.may_throw(compressor);
             self.right = right;
-            var parent;
-            while (parent = compressor.parent(level++)) {
+            for (var parent; parent = compressor.parent(level++); node = parent) {
                 if (parent === scope) return false;
                 if (parent instanceof AST_Try) {
-                    if (parent.bfinally) return true;
-                    if (may_throw && parent.bcatch) return true;
+                    if (parent.bfinally && parent.bfinally !== node) return true;
+                    if (may_throw && parent.bcatch && parent.bcatch !== node) return true;
                 }
             }
         }
 
-        function strip_assignment() {
+        function strip_assignment(def) {
+            if (def) def.fixed = false;
             return (self.operator != "=" ? make_node(AST_Binary, self, {
                 operator: self.operator.slice(0, -1),
                 left: self.left,
-                right: self.right
+                right: self.right,
             }) : maintain_this_binding(compressor, compressor.parent(), self, self.right)).optimize(compressor);
         }
     });
@@ -11211,7 +11366,11 @@ merge(Compressor.prototype, {
             return make_sequence(self, expressions);
         }
         if (!compressor.option("conditionals")) return self;
-        var condition = self.condition.is_truthy() || self.condition.evaluate(compressor, true);
+        var condition = self.condition;
+        if (compressor.option("booleans") && !condition.has_side_effects(compressor)) {
+            mark_duplicate_condition(compressor, condition);
+        }
+        condition = fuzzy_eval(compressor, condition);
         if (!condition) {
             AST_Node.warn("Condition always false [{file}:{line},{col}]", self.start);
             return make_sequence(self, [ self.condition, self.alternative ]).optimize(compressor);
@@ -11675,7 +11834,11 @@ merge(Compressor.prototype, {
                 } else if (compressor.has_directive("use strict")
                     || fn.name
                     || fn.rest
-                    || !(fn_parent instanceof AST_Call && index < fn_parent.args.length)
+                    || !(fn_parent instanceof AST_Call
+                        && index < fn_parent.args.length
+                        && all(fn_parent.args.slice(0, index + 1), function(arg) {
+                            return !(arg instanceof AST_Spread);
+                        }))
                     || !all(fn.argnames, function(argname) {
                         return argname instanceof AST_SymbolFunarg;
                     })) {
@@ -11816,7 +11979,7 @@ merge(Compressor.prototype, {
             var props = expr.properties;
             for (var i = props.length; --i >= 0;) {
                 var prop = props[i];
-                if (prop.key != key) continue;
+                if (prop.key !== key) continue;
                 if (!all(props, can_hoist_property)) break;
                 if (!safe_to_flatten(prop.value, compressor)) break;
                 props = props.map(function(prop) {

lib/minify.js

@@ -100,7 +100,7 @@ function minify(files, options) {
         if (options.keep_fnames) set_shorthand("keep_fnames", options, [ "compress", "mangle" ]);
         if (options.toplevel) set_shorthand("toplevel", options, [ "compress", "mangle" ]);
         if (options.v8) set_shorthand("v8", options, [ "mangle", "output" ]);
-        if (options.webkit) set_shorthand("webkit", options, [ "mangle", "output" ]);
+        if (options.webkit) set_shorthand("webkit", options, [ "compress", "mangle", "output" ]);
         var quoted_props;
         if (options.mangle) {
             options.mangle = defaults(options.mangle, {

lib/mozilla-ast.js

@@ -1134,58 +1134,54 @@
     }
 
     function map(moztype, mytype, propmap) {
-        var moz_to_me = "function From_Moz_" + moztype + "(M){\n";
-        moz_to_me += "return new U2." + mytype.name + "({\n" +
-            "start: my_start_token(M),\n" +
-            "end: my_end_token(M)";
-
-        var me_to_moz = "function To_Moz_" + moztype + "(M){\n";
-        me_to_moz += "return {\n" +
-            "type: " + JSON.stringify(moztype);
+        var moz_to_me = [
+            "start: my_start_token(M)",
+            "end: my_end_token(M)",
+        ];
+        var me_to_moz = [
+            "type: " + JSON.stringify(moztype),
+        ];
 
         if (propmap) propmap.split(/\s*,\s*/).forEach(function(prop) {
             var m = /([a-z0-9$_]+)(=|@|>|%)([a-z0-9$_]+)/i.exec(prop);
             if (!m) throw new Error("Can't understand property map: " + prop);
             var moz = m[1], how = m[2], my = m[3];
-            moz_to_me += ",\n" + my + ": ";
-            me_to_moz += ",\n" + moz + ": ";
             switch (how) {
               case "@":
-                moz_to_me += "M." + moz + ".map(from_moz)";
-                me_to_moz += "M." +  my + ".map(to_moz)";
+                moz_to_me.push(my + ": M." + moz + ".map(from_moz)");
+                me_to_moz.push(moz + ": M." +  my + ".map(to_moz)");
                 break;
               case ">":
-                moz_to_me += "from_moz(M." + moz + ")";
-                me_to_moz += "to_moz(M." + my + ")";
+                moz_to_me.push(my + ": from_moz(M." + moz + ")");
+                me_to_moz.push(moz + ": to_moz(M." + my + ")");
                 break;
               case "=":
-                moz_to_me += "M." + moz;
-                me_to_moz += "M." + my;
+                moz_to_me.push(my + ": M." + moz);
+                me_to_moz.push(moz + ": M." + my);
                 break;
               case "%":
-                moz_to_me += "from_moz(M." + moz + ").body";
-                me_to_moz += "to_moz_block(M)";
+                moz_to_me.push(my + ": from_moz(M." + moz + ").body");
+                me_to_moz.push(moz + ": to_moz_block(M)");
                 break;
               default:
                 throw new Error("Can't understand operator in propmap: " + prop);
             }
         });
 
-        moz_to_me += "\n})\n}";
-        me_to_moz += "\n}\n}";
-
-        //moz_to_me = parse(moz_to_me).print_to_string({ beautify: true });
-        //me_to_moz = parse(me_to_moz).print_to_string({ beautify: true });
-        //console.log(moz_to_me);
-
-        moz_to_me = new Function("U2", "my_start_token", "my_end_token", "from_moz", "return(" + moz_to_me + ")")(
-            exports, my_start_token, my_end_token, from_moz
-        );
-        me_to_moz = new Function("to_moz", "to_moz_block", "to_moz_scope", "return(" + me_to_moz + ")")(
-            to_moz, to_moz_block, to_moz_scope
-        );
-        MOZ_TO_ME[moztype] = moz_to_me;
-        def_to_moz(mytype, me_to_moz);
+        MOZ_TO_ME[moztype] = new Function("U2", "my_start_token", "my_end_token", "from_moz", [
+            "return function From_Moz_" + moztype + "(M) {",
+            "    return new U2.AST_" + mytype.TYPE + "({",
+            moz_to_me.join(",\n"),
+            "    });",
+            "};",
+        ].join("\n"))(exports, my_start_token, my_end_token, from_moz);
+        def_to_moz(mytype, new Function("to_moz", "to_moz_block", "to_moz_scope", [
+            "return function To_Moz_" + moztype + "(M) {",
+            "    return {",
+            me_to_moz.join(",\n"),
+            "    };",
+            "};",
+        ].join("\n"))(to_moz, to_moz_block, to_moz_scope));
     }
 
     var FROM_MOZ_STACK = null;

lib/parse.js

@@ -1334,21 +1334,19 @@ function parse($TEXT, options) {
         if (is("punc", "{")) {
             body = block_();
             value = null;
-            if (S.input.has_directive("use strict")) {
-                argnames.forEach(strict_verify_symbol);
-            }
         } else {
             body = [];
             handle_regexp();
             value = maybe_assign();
         }
+        var is_strict = S.input.has_directive("use strict");
         S.input.pop_directives_stack();
         --S.in_function;
         S.in_loop = loop;
         S.labels = labels;
         S.in_generator = was_gen;
         S.in_async = was_async;
-        return new (async ? AST_AsyncArrow : AST_Arrow)({
+        var node = new (async ? AST_AsyncArrow : AST_Arrow)({
             start: start,
             argnames: argnames,
             rest: rest,
@@ -1356,6 +1354,8 @@ function parse($TEXT, options) {
             value: value,
             end: prev(),
         });
+        if (is_strict) node.each_argname(strict_verify_symbol);
+        return node;
     }
 
     var function_ = function(ctor) {
@@ -1388,23 +1388,24 @@ function parse($TEXT, options) {
         S.in_loop = 0;
         S.labels = [];
         var body = block_();
-        if (S.input.has_directive("use strict")) {
-            if (name) strict_verify_symbol(name);
-            argnames.forEach(strict_verify_symbol);
-            if (argnames.rest) strict_verify_symbol(argnames.rest);
-        }
+        var is_strict = S.input.has_directive("use strict");
         S.input.pop_directives_stack();
         --S.in_function;
         S.in_loop = loop;
         S.labels = labels;
         S.in_generator = was_gen;
         S.in_async = was_async;
-        return new ctor({
+        var node = new ctor({
             name: name,
             argnames: argnames,
             rest: argnames.rest || null,
             body: body
         });
+        if (is_strict) {
+            if (name) strict_verify_symbol(name);
+            node.each_argname(strict_verify_symbol);
+        }
+        return node;
     };
 
     function if_() {

package.json

@@ -3,7 +3,7 @@
   "description": "JavaScript parser, mangler/compressor and beautifier toolkit",
   "author": "Mihai Bazon <mihai.bazon@gmail.com> (http://lisperator.net/)",
   "license": "BSD-2-Clause",
-  "version": "3.13.9",
+  "version": "3.13.10",
   "engines": {
     "node": ">=0.8.0"
   },

test/benchmark.js

@@ -16,7 +16,7 @@ var urls = [
     "https://code.angularjs.org/1.7.8/angular.js",
     "https://unpkg.com/mathjs@6.2.3/dist/math.js",
     "https://unpkg.com/react@15.3.2/dist/react.js",
-    "https://cdnjs.cloudflare.com/ajax/libs/d3/5.12.0/d3.js",
+    "https://cdnjs.cloudflare.com/ajax/libs/d3/6.7.0/d3.js",
     "https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.js",
     "https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js",
     "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.12.2/ember.prod.js",

test/compress/awaits.js

@@ -1758,3 +1758,268 @@ issue_4987: {
     ]
     node_version: ">=8"
 }
+
+issue_5001: {
+    options = {
+        awaits: true,
+        inline: true,
+        side_effects: true,
+    }
+    input: {
+        var a = 0;
+        (async function() {
+            a++ | await 42;
+        })();
+        console.log(a ? "PASS" : "FAIL");
+    }
+    expect: {
+        var a = 0;
+        void a++;
+        console.log(a ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_5019_1: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        (function(a) {
+            (async function() {
+                await 42;
+                console.log(a);
+            })();
+            a = "PASS";
+        })("FAIL");
+    }
+    expect: {
+        (function(a) {
+            (async function() {
+                await 42;
+                console.log(a);
+            })();
+            a = "PASS";
+        })("FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_5019_2: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        console.log("sync", function(a) {
+            (async function() {
+                console.log(await "async", a);
+            })();
+            return a = "PASS";
+        }("FAIL"));
+    }
+    expect: {
+        console.log("sync", function(a) {
+            (async function() {
+                console.log(await "async", a);
+            })();
+            return a = "PASS";
+        }("FAIL"));
+    }
+    expect_stdout: [
+        "sync PASS",
+        "async PASS",
+    ]
+    node_version: ">=8"
+}
+
+issue_5019_3: {
+    options = {
+        inline: true,
+        toplevel: true,
+    }
+    input: {
+        for (var i in "foo") {
+            (function(a) {
+                (async function() {
+                    console.log(await "async", a);
+                })();
+            })(i);
+            console.log("sync", i);
+        }
+    }
+    expect: {
+        for (var i in "foo") {
+            (function(a) {
+                (async function() {
+                    console.log(await "async", a);
+                })();
+            })(i);
+            console.log("sync", i);
+        }
+    }
+    expect_stdout: [
+        "sync 0",
+        "sync 1",
+        "sync 2",
+        "async 0",
+        "async 1",
+        "async 2",
+    ]
+    node_version: ">=8"
+}
+
+issue_5023_1: {
+    options = {
+        awaits: true,
+        reduce_vars: true,
+        side_effects: true,
+    }
+    input: {
+        (async function() {
+            let a = a;
+        })();
+        console.log("PASS");
+    }
+    expect: {
+        (async function() {
+            let a = a;
+        })();
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_5023_2: {
+    options = {
+        awaits: true,
+        reduce_vars: true,
+        side_effects: true,
+    }
+    input: {
+        (async function() {
+            let a;
+            a = a;
+        })();
+        console.log("PASS");
+    }
+    expect: {
+        (function() {
+            let a;
+            a = a;
+        })();
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_5032_normal: {
+    options = {
+        merge_vars: true,
+        webkit: false,
+    }
+    input: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        async function f(a) {
+            var b = log(a), c = b;
+            log(b);
+            log(c);
+        }
+        f("PASS");
+    }
+    expect: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        async function f(c) {
+            var b = log(c), c = b;
+            log(b);
+            log(c);
+        }
+        f("PASS");
+    }
+    expect_stdout: [
+        "PASS",
+        "PASS",
+        "PASS",
+    ]
+    node_version: ">=8"
+}
+
+issue_5032_webkit: {
+    options = {
+        merge_vars: true,
+        webkit: true,
+    }
+    input: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        async function f(a) {
+            var b = log(a), c = b;
+            log(b);
+            log(c);
+        }
+        f("PASS");
+    }
+    expect: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        async function f(a) {
+            var b = log(a), c = b;
+            log(b);
+            log(c);
+        }
+        f("PASS");
+    }
+    expect_stdout: [
+        "PASS",
+        "PASS",
+        "PASS",
+    ]
+    node_version: ">=8"
+}
+
+issue_5034: {
+    options = {
+        functions: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function() {
+            var await = function f() {
+                return async function() {
+                    return f;
+                };
+            };
+            await()().then(function(value) {
+                console.log(value === await ? "PASS" : "FAIL");
+            });
+        })();
+    }
+    expect: {
+        (function() {
+            var await = function f() {
+                return async function() {
+                    return f;
+                };
+            };
+            await()().then(function(value) {
+                console.log(value === await ? "PASS" : "FAIL");
+            });
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}

test/compress/booleans.js

@@ -29,6 +29,383 @@ iife_boolean_context: {
     ]
 }
 
+de_morgan_1a: {
+    options = {
+        booleans: true,
+    }
+    input: {
+        function f(a) {
+            return a || a;
+        }
+        console.log(f(null), f(42));
+    }
+    expect: {
+        function f(a) {
+            return a;
+        }
+        console.log(f(null), f(42));
+    }
+    expect_stdout: "null 42"
+}
+
+de_morgan_1b: {
+    options = {
+        booleans: true,
+    }
+    input: {
+        function f(a) {
+            return a && a;
+        }
+        console.log(f(null), f(42));
+    }
+    expect: {
+        function f(a) {
+            return a;
+        }
+        console.log(f(null), f(42));
+    }
+    expect_stdout: "null 42"
+}
+
+de_morgan_1c: {
+    options = {
+        booleans: true,
+    }
+    input: {
+        console.log(delete (NaN && NaN));
+    }
+    expect: {
+        console.log(delete (0, NaN));
+    }
+    expect_stdout: "true"
+}
+
+de_morgan_2a: {
+    options = {
+        booleans: true,
+        conditionals: true,
+    }
+    input: {
+        function f(a, b) {
+            return a || (a || b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a || b;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "undefined {}",
+        "42 42",
+    ]
+}
+
+de_morgan_2b: {
+    options = {
+        booleans: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b) {
+            return a || (a && b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "null null",
+        "42 42",
+    ]
+}
+
+de_morgan_2c: {
+    options = {
+        booleans: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b) {
+            return a && (a || b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "null null",
+        "42 42",
+    ]
+}
+
+de_morgan_2d: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        function f(a, b) {
+            return a && (a && b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a && b;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "null null",
+        "undefined {}",
+    ]
+}
+
+de_morgan_3a: {
+    options = {
+        booleans: true,
+        conditionals: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a || ((a || b) || c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a || b || c;
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "undefined {} true true",
+        "42 42 42 42",
+    ]
+}
+
+de_morgan_3b: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a || ((a || b) && c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a || b && c;
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "false false undefined {}",
+        "42 42 42 42",
+    ]
+}
+
+de_morgan_3c: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a || ((a && b) || c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a || c;
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "undefined {} undefined {}",
+        "42 42 42 42",
+    ]
+}
+
+de_morgan_3d: {
+    options = {
+        booleans: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a || ((a && b) && c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a;
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "null null null null",
+        "42 42 42 42",
+    ]
+}
+
+de_morgan_3e: {
+    options = {
+        booleans: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a && ((a || b) || c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a;
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "null null null null",
+        "42 42 42 42",
+    ]
+}
+
+de_morgan_3f: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a && ((a || b) && c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a && c;
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "null null null null",
+        "undefined {} undefined {}",
+    ]
+}
+
+de_morgan_3g: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a && ((a && b) || c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a && (b || c);
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "null null null null",
+        "undefined {} true true",
+    ]
+}
+
+de_morgan_3h: {
+    options = {
+        booleans: true,
+        conditionals: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a && ((a && b) && c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a && b && c;
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "null null null null",
+        "false false undefined {}",
+    ]
+}
+
+conditional_chain: {
+    options = {
+        booleans: true,
+        conditionals: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b) {
+            return a ? a : b ? b : 42;
+        }
+        console.log(f("PASS", "FAIL"));
+    }
+    expect: {
+        function f(a, b) {
+            return a || b || 42;
+        }
+        console.log(f("PASS", "FAIL"));
+    }
+    expect_stdout: "PASS"
+}
+
 issue_3465_1: {
     options = {
         booleans: true,
@@ -181,3 +558,79 @@ issue_4374: {
     }
     expect_stdout: "0"
 }
+
+issue_5028_1: {
+    options = {
+        booleans: true,
+        conditionals: true,
+    }
+    input: {
+        var a = 1;
+        console.log(function() {
+            return a-- ? a-- ? "FAIL 1" : "PASS" : "FAIL 2";
+        }());
+    }
+    expect: {
+        var a = 1;
+        console.log(function() {
+            return a-- ? a-- ? "FAIL 1" : "PASS" : "FAIL 2";
+        }());
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5028_2: {
+    options = {
+        booleans: true,
+        conditionals: true,
+        dead_code: true,
+        if_return: true,
+    }
+    input: {
+        var a = 1;
+        (function() {
+            if (a--)
+                if (a--)
+                    a = "FAIL";
+                else
+                    return;
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = 1;
+        (function() {
+            a-- && a-- && (a = "FAIL");
+        })();
+        console.log(a);
+    }
+    expect_stdout: "-1"
+}
+
+issue_5028_3: {
+    options = {
+        booleans: true,
+        conditionals: true,
+        evaluate: true,
+        if_return: true,
+    }
+    input: {
+        var a = 1;
+        (function() {
+            if (a--)
+                if (a--)
+                    a = "FAIL";
+                else
+                    return;
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = 1;
+        (function() {
+            a-- && a-- && (a = "FAIL");
+        })();
+        console.log(a);
+    }
+    expect_stdout: "-1"
+}

test/compress/classes.js

@@ -1748,3 +1748,130 @@ issue_4992: {
     expect_stdout: "function"
     node_version: ">=12"
 }
+
+issue_4996_1: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 1;
+        console.log(new class A {
+            p = a-- && new A();
+        }().p.p);
+    }
+    expect: {
+        var a = 1;
+        console.log(new class A {
+            p = a-- && new A();
+        }().p.p);
+    }
+    expect_stdout: "0"
+    node_version: ">=12"
+}
+
+issue_4996_2: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = 1;
+        console.log(new class A {
+            p = a-- && new A();
+        }().p.p);
+    }
+    expect: {
+        var a = 1;
+        console.log(new class A {
+            p = a-- && new A();
+        }().p.p);
+    }
+    expect_stdout: "0"
+    node_version: ">=12"
+}
+
+issue_5015_1: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        "use strict";
+        var a;
+        try {
+            (class a {
+                [a]() {}
+            });
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        "use strict";
+        var a;
+        try {
+            (class a {
+                [a]() {}
+            });
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_5015_2: {
+    options = {
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+    }
+    input: {
+        "use strict";
+        try {
+            new class A {
+                [(A, 42)]() {}
+            }();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            new class A {
+                [(A, 42)]() {}
+            }();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_5015_3: {
+    options = {
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+    }
+    input: {
+        "use strict";
+        (class A {
+            static f() {
+                return A;
+            }
+        });
+        console.log("PASS");
+    }
+    expect: {
+        "use strict";
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}

test/compress/collapse_vars.js

@@ -4728,7 +4728,7 @@ cascade_statement: {
         }
         function f3(a, b) {
             for (; a < b; a++)
-                if (c = a, a && b)
+                if ((c = a) && b)
                     var c = c = b(a);
         }
     }
@@ -8863,7 +8863,7 @@ issue_4732_1: {
     expect: {
         var a = 0;
         (function(b) {
-            (b = a++) && (b && console.log("PASS"));
+            (b = a++) && console.log("PASS");
         })(a++);
     }
     expect_stdout: "PASS"

test/compress/conditionals.js

@@ -822,6 +822,33 @@ cond_13: {
     }
 }
 
+cond_14: {
+    options = {
+        booleans: true,
+        conditionals: true,
+        side_effects: true,
+    }
+    input: {
+        function f(a) {
+            if (a)
+                if (a)
+                    console.log("PASS");
+                else
+                    console.log("FAIL");
+        }
+        f(null);
+        f(42);
+    }
+    expect: {
+        function f(a) {
+            a && console.log("PASS");
+        }
+        f(null);
+        f(42);
+    }
+    expect_stdout: "PASS"
+}
+
 ternary_boolean_consequent: {
     options = {
         booleans: true,

test/compress/dead-code.js

@@ -939,6 +939,185 @@ catch_return_assign: {
     expect_stdout: "PASS"
 }
 
+catch_return_assign_may_throw: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        function f() {
+            try {
+                throw "FAIL";
+            } catch (e) {
+                return e = console.log("PASS");
+            }
+        }
+        f();
+    }
+    expect: {
+        function f() {
+            try {
+                throw "FAIL";
+            } catch (e) {
+                return console.log("PASS");
+            }
+        }
+        f();
+    }
+    expect_stdout: "PASS"
+}
+
+finally_return_assign: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        console.log(function(a) {
+            try {
+                throw "FAIL";
+            } finally {
+                return a = "PASS";
+            }
+        }());
+    }
+    expect: {
+        console.log(function(a) {
+            try {
+                throw "FAIL";
+            } finally {
+                return "PASS";
+            }
+        }());
+    }
+    expect_stdout: "PASS"
+}
+
+last_assign_statement: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        function f(a) {
+            a = a("PASS");
+        }
+        f(console.log);
+    }
+    expect: {
+        function f(a) {
+            a("PASS");
+        }
+        f(console.log);
+    }
+    expect_stdout: "PASS"
+}
+
+last_assign_if_else: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        function f(a) {
+            if (a)
+                a = console.log("foo");
+            else {
+                console.log("bar");
+                a = console.log("baz");
+            }
+        }
+        f(42);
+        f(null);
+    }
+    expect: {
+        function f(a) {
+            if (a)
+                console.log("foo");
+            else {
+                console.log("bar");
+                console.log("baz");
+            }
+        }
+        f(42);
+        f(null);
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+        "baz",
+    ]
+}
+
+last_assign_catch: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        function f() {
+            try {
+                throw "FAIL";
+            } catch (e) {
+                e = console.log("PASS");
+            }
+        }
+        f();
+    }
+    expect: {
+        function f() {
+            try {
+                throw "FAIL";
+            } catch (e) {
+                console.log("PASS");
+            }
+        }
+        f();
+    }
+    expect_stdout: "PASS"
+}
+
+last_assign_finally: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        function f(a) {
+            try {
+                throw a.log;
+            } catch (e) {
+                a = e;
+            } finally {
+                a = a("PASS");
+            }
+        }
+        f(console);
+    }
+    expect: {
+        function f(a) {
+            try {
+                throw a.log;
+            } catch (e) {
+                a = e;
+            } finally {
+                a("PASS");
+            }
+        }
+        f(console);
+    }
+    expect_stdout: "PASS"
+}
+
+consecutive_assignments: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        while (a = void 0, a = "PASS", console.log(a));
+        var a;
+    }
+    expect: {
+        while (void 0, a = "PASS", console.log(a));
+        var a;
+    }
+    expect_stdout: "PASS"
+}
+
 issue_3578: {
     options = {
         dead_code: true,
@@ -1420,3 +1599,37 @@ issue_4570: {
     }
     expect_stdout: "NaN"
 }
+
+issue_5030: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        (function(a, b) {
+            a = function f() {
+                if (a)
+                    if (b--)
+                        setImmediate(f);
+                    else
+                        console.log("FAIL");
+                else
+                    console.log("PASS");
+            }();
+        })(42, 1);
+    }
+    expect: {
+        (function(a, b) {
+            a = function f() {
+                if (a)
+                    if (b--)
+                        setImmediate(f);
+                    else
+                        console.log("FAIL");
+                else
+                    console.log("PASS");
+            }();
+        })(42, 1);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=0.12"
+}

test/compress/default-values.js

@@ -422,7 +422,9 @@ inline_loop_1: {
 inline_loop_2: {
     options = {
         inline: true,
+        sequences: true,
         toplevel: true,
+        unused: true,
     }
     input: {
         while (function(a = [ "PASS" ]) {
@@ -432,10 +434,11 @@ inline_loop_2: {
         }());
     }
     expect: {
-        while (a = [ "PASS" ], a = function f(b) {
-            console.log(a[b]);
-        }(0), void 0) ;
-        var a;
+        while (a = [ "PASS" ],
+            b = void 0,
+            b = 0,
+            void (a = void console.log(a[b])));
+        var a, b;
     }
     expect_stdout: "PASS"
     node_version: ">=6"
@@ -1726,3 +1729,28 @@ issue_4916: {
     expect_stdout: "undefined"
     node_version: ">=6"
 }
+
+issue_4994: {
+    options = {
+        loops: true,
+        unused: true,
+    }
+    input: {
+        var a = "FAIL";
+        (function(b = function() {
+            for (a in { PASS: 42 });
+        }()) {
+            var a;
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = "FAIL";
+        (function(b = function() {
+            for (a in { PASS: 42 });
+        }()) {})();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}

test/compress/destructured.js

@@ -2592,3 +2592,58 @@ issue_4608_2: {
     expect_stdout: "f"
     node_version: ">=6"
 }
+
+issue_4994: {
+    options = {
+        loops: true,
+        unused: true,
+    }
+    input: {
+        var a = "FAIL";
+        (function([
+            {
+                [function() {
+                    for (a in { PASS: null });
+                }()]: b,
+            },
+        ]) {
+            var a;
+        })([ 42 ]);
+        console.log(a);
+    }
+    expect: {
+        var a = "FAIL";
+        (function([
+            {
+                [function() {
+                    for (a in { PASS: null });
+                }()]: b,
+            },
+        ]) {})([ 42 ]);
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5017: {
+    options = {
+        collapse_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = function() {};
+        var b = c = a;
+        var c = [ c ] = [ c ];
+        console.log(c[0] === a ? "PASS" : "FAIL");
+    }
+    expect: {
+        var a = function() {};
+        var b = a;
+        var c = [ c ] = [ c = a ];
+        console.log(c[0] === a ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}

test/compress/functions.js

@@ -6228,3 +6228,58 @@ recursive_collapse: {
     }
     expect_stdout: "PASS"
 }
+
+issue_5025: {
+    options = {
+        collapse_vars: true,
+        inline: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        function f(a) {
+            function g() {
+                b = 42;
+            }
+            g(b = a);
+            var b = this;
+            console.log(typeof b);
+        }
+        f();
+    }
+    expect: {
+        function f(a) {
+            b = a,
+            void (b = 42);
+            var b = this;
+            console.log(typeof b);
+        }
+        f();
+    }
+    expect_stdout: "object"
+}
+
+issue_5036: {
+    options = {
+        functions: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(typeof function() {
+            var await = function f() {
+                return f;
+            };
+            return await() === await;
+        }() ? "PASS" : "FAIL");
+    }
+    expect: {
+        console.log(typeof function() {
+            function await() {
+                return await;
+            }
+            return await() === await;
+        }() ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+}

test/compress/imports.js

@@ -94,13 +94,15 @@ drop_unused: {
     }
     input: {
         import a, * as b from "foo";
-        import { c, bar as d } from "baz";
-        console.log(c);
+        import { c } from "bar";
+        import { d, _ as e } from "baz";
+        console.log(d);
     }
     expect: {
         import "foo";
-        import { c as c } from "baz";
-        console.log(c);
+        import "bar";
+        import { d as d } from "baz";
+        console.log(d);
     }
 }
 

test/compress/join_vars.js

@@ -1015,7 +1015,7 @@ issue_3856: {
         console.log(function() {
             (function() {
                 var a, b;
-                if (a) return !!a;
+                if (a) return a, 1;
                 for (a = 0; !console;);
                 return 0;
             })();

test/compress/keep_fargs.js

@@ -1158,8 +1158,8 @@ replace_all_var_scope: {
         var a = 100, b = 10;
         (function(r, a) {
             switch (~a) {
-            case (b += a):
-            case a++:
+              case (b += a):
+              case a++:
             }
         })(--b, a);
         console.log(a, b);
@@ -1168,8 +1168,8 @@ replace_all_var_scope: {
         var a = 100, b = 10;
         (function(c) {
             switch (~a) {
-            case (b += a):
-            case c++:
+              case (b += a):
+              case c++:
             }
         })((--b, a));
         console.log(a, b);

test/compress/merge_vars.js

@@ -3075,7 +3075,7 @@ issue_4237_2: {
         console.log(function(a) {
             do {
                 switch (0) {
-                  case 0:
+                  default:
                     var b = a++;
                     if (b)
                         return "FAIL";

test/compress/nullish.js

@@ -110,6 +110,158 @@ conditional_assignment_4: {
     node_version: ">=14"
 }
 
+de_morgan_1: {
+    options = {
+        booleans: true,
+    }
+    input: {
+        function f(a) {
+            return a ?? a;
+        }
+        console.log(f(null), f(42));
+    }
+    expect: {
+        function f(a) {
+            return a;
+        }
+        console.log(f(null), f(42));
+    }
+    expect_stdout: "null 42"
+    node_version: ">=14"
+}
+
+de_morgan_2a: {
+    options = {
+        booleans: true,
+        conditionals: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b) {
+            return a || (a ?? b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a || (a ?? b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "undefined {}",
+        "42 42",
+    ]
+    node_version: ">=14"
+}
+
+de_morgan_2b: {
+    options = {
+        booleans: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b) {
+            return a && (a ?? b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "null null",
+        "42 42",
+    ]
+    node_version: ">=14"
+}
+
+de_morgan_2c: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        function f(a, b) {
+            return a ?? (a || b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a ?? b;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "undefined {}",
+        "42 42",
+    ]
+    node_version: ">=14"
+}
+
+de_morgan_2d: {
+    options = {
+        booleans: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b) {
+            return a ?? (a && b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "null null",
+        "42 42",
+    ]
+    node_version: ">=14"
+}
+
+de_morgan_2e: {
+    options = {
+        booleans: true,
+        conditionals: true,
+    }
+    input: {
+        function f(a, b) {
+            return a ?? (a ?? b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a ?? b;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "undefined {}",
+        "42 42",
+    ]
+    node_version: ">=14"
+}
+
 issue_4679: {
     options = {
         comparisons: true,

test/compress/reduce_vars.js

@@ -2071,72 +2071,6 @@ issue_1670_2: {
 }
 
 issue_1670_3: {
-    options = {
-        comparisons: true,
-        conditionals: true,
-        dead_code: true,
-        evaluate: true,
-        reduce_funcs: true,
-        reduce_vars: true,
-        side_effects: true,
-        switches: true,
-        typeofs: true,
-        unused: true,
-    }
-    input: {
-        (function f() {
-            switch (1) {
-              case 0:
-                var a = true;
-                break;
-              case 1:
-                if (typeof a === "undefined") console.log("PASS");
-                else console.log("FAIL");
-            }
-        })();
-    }
-    expect: {
-        (function() {
-            var a;
-            void 0 === a ? console.log("PASS") : console.log("FAIL");
-        })();
-    }
-    expect_stdout: "PASS"
-}
-
-issue_1670_4: {
-    options = {
-        conditionals: true,
-        dead_code: true,
-        evaluate: true,
-        passes: 2,
-        reduce_funcs: true,
-        reduce_vars: true,
-        side_effects: true,
-        switches: true,
-        unused: true,
-    }
-    input: {
-        (function f() {
-            switch (1) {
-              case 0:
-                var a = true;
-                break;
-              case 1:
-                if (typeof a === "undefined") console.log("PASS");
-                else console.log("FAIL");
-            }
-        })();
-    }
-    expect: {
-        (function() {
-            console.log("PASS");
-        })();
-    }
-    expect_stdout: "PASS"
-}
-
-issue_1670_5: {
     options = {
         conditionals: true,
         dead_code: true,
@@ -2168,7 +2102,7 @@ issue_1670_5: {
     expect_stdout: "1"
 }
 
-issue_1670_6: {
+issue_1670_4: {
     options = {
         conditionals: true,
         dead_code: true,

test/compress/spreads.js

@@ -1156,3 +1156,23 @@ issue_4882_3: {
     ]
     node_version: ">=8"
 }
+
+issue_5006: {
+    options = {
+        arguments: true,
+    }
+    input: {
+        console.log(function(b, c) {
+            c = "FAIL 2";
+            return arguments[1];
+        }(...[], "FAIL 1") || "PASS");
+    }
+    expect: {
+        console.log(function(b, c) {
+            c = "FAIL 2";
+            return arguments[1];
+        }(...[], "FAIL 1") || "PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}

test/compress/switches.js

@@ -113,7 +113,7 @@ constant_switch_5: {
         // the break inside the if ruins our job
         // we can still get rid of irrelevant cases.
         switch (1) {
-          case 1:
+          default:
             x();
             if (foo) break;
             y();
@@ -300,6 +300,37 @@ drop_default_2: {
     }
 }
 
+drop_default_3: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        function f() {
+            console.log("PASS");
+            return 42;
+        }
+        switch (42) {
+          case f():
+            break;
+          case void console.log("FAIL"):
+          default:
+        }
+    }
+    expect: {
+        function f() {
+            console.log("PASS");
+            return 42;
+        }
+        switch (42) {
+          case f():
+          case void console.log("FAIL"):
+        }
+    }
+    expect_stdout: "PASS"
+}
+
 keep_default: {
     options = {
         dead_code: true,
@@ -423,7 +454,6 @@ drop_case_3: {
         switch ({}.p) {
           default:
           case void 0:
-            break;
           case c = "FAIL":
         }
         console.log(c);
@@ -454,7 +484,168 @@ drop_case_4: {
     expect_stdout: "PASS"
 }
 
-keep_case: {
+drop_case_5: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        switch (42) {
+          case void console.log("PASS 1"):
+            console.log("FAIL 1");
+          case 42:
+          case console.log("FAIL 2"):
+            console.log("PASS 2");
+        }
+    }
+    expect: {
+        switch (42) {
+          default:
+            void console.log("PASS 1");
+            console.log("PASS 2");
+        }
+    }
+    expect_stdout: [
+        "PASS 1",
+        "PASS 2",
+    ]
+}
+
+drop_case_6: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        switch (console.log("PASS 1"), 2) {
+          case 0:
+            console.log("FAIL 1");
+          case (console.log("PASS 2"), 1):
+            console.log("FAIL 2");
+        }
+    }
+    expect: {
+        switch (console.log("PASS 1"), 2) {
+          case (console.log("PASS 2"), 1):
+        }
+    }
+    expect_stdout: [
+        "PASS 1",
+        "PASS 2",
+    ]
+}
+
+drop_case_7: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        switch (2) {
+          case 0:
+            console.log("FAIL 1");
+          case (console.log("PASS 1"), 1):
+            console.log("FAIL 2");
+          case 2:
+            console.log("PASS 2");
+        }
+    }
+    expect: {
+        switch (2) {
+          default:
+            console.log("PASS 1"), 1;
+            console.log("PASS 2");
+        }
+    }
+    expect_stdout: [
+        "PASS 1",
+        "PASS 2",
+    ]
+}
+
+drop_case_8: {
+    options = {
+        dead_code: true,
+        switches: true,
+    }
+    input: {
+        function log(msg) {
+            console.log(msg);
+            return msg;
+        }
+        switch (log("foo")) {
+          case "bar":
+            log("moo");
+            break;
+          case log("baz"):
+            log("moo");
+            break;
+          default:
+            log("moo");
+        }
+    }
+    expect: {
+        function log(msg) {
+            console.log(msg);
+            return msg;
+        }
+        switch (log("foo")) {
+          case "bar":
+          case log("baz"):
+          default:
+            log("moo");
+        }
+    }
+    expect_stdout: [
+        "foo",
+        "baz",
+        "moo",
+    ]
+}
+
+drop_case_9: {
+    options = {
+        dead_code: true,
+        switches: true,
+    }
+    input: {
+        function log(msg) {
+            console.log(msg);
+            return msg;
+        }
+        switch (log("foo")) {
+          case log("bar"):
+            log("moo");
+            break;
+          case "baz":
+            log("moo");
+            break;
+          default:
+            log("moo");
+        }
+    }
+    expect: {
+        function log(msg) {
+            console.log(msg);
+            return msg;
+        }
+        switch (log("foo")) {
+          default:
+            log("bar");
+            log("moo");
+        }
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+        "moo",
+    ]
+}
+
+keep_case_1: {
     options = {
         dead_code: true,
         switches: true,
@@ -474,6 +665,76 @@ keep_case: {
     }
 }
 
+keep_case_2: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        switch ("foo") {
+          case console.log("bar"):
+          case console.log("baz"), "moo":
+        }
+    }
+    expect: {
+        switch ("foo") {
+          case console.log("bar"):
+          case console.log("baz"), "moo":
+        }
+    }
+    expect_stdout: [
+        "bar",
+        "baz",
+    ]
+}
+
+keep_case_3: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        var a;
+        switch (void console.log("PASS")) {
+          case a:
+          case console.log("FAIL"), 42:
+        }
+    }
+    expect: {
+        var a;
+        switch (void console.log("PASS")) {
+          case a:
+          case console.log("FAIL"), 42:
+        }
+    }
+    expect_stdout: "PASS"
+}
+
+keep_case_4: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        var a;
+        switch (void console.log("PASS")) {
+          case a:
+          case void console.log("FAIL"):
+        }
+    }
+    expect: {
+        var a;
+        switch (void console.log("PASS")) {
+          case a:
+          case void console.log("FAIL"):
+        }
+    }
+    expect_stdout: "PASS"
+}
+
 issue_376: {
     options = {
         dead_code: true,
@@ -661,7 +922,7 @@ issue_1680_1: {
           case f(0):
           case f(1):
             f(2);
-          case 2:
+          default:
             f(5);
         }
     }
@@ -924,7 +1185,6 @@ issue_2535: {
     }
     expect: {
         w(), 42;
-        42;
         y();
         z();
     }
@@ -950,7 +1210,6 @@ issue_1750: {
     expect: {
         var a = 0, b = 1;
         true;
-        a, true;
         b = 2;
         console.log(a, b);
     }
@@ -1088,7 +1347,8 @@ drop_switch_6: {
         }
     }
     expect: {
-        A === B;
+        A;
+        B;
         x();
         C !== D;
         y();
@@ -1181,3 +1441,170 @@ issue_4059: {
     }
     expect_stdout: "PASS"
 }
+
+issue_5008_1: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        reduce_vars: true,
+        switches: true,
+        unsafe: true,
+    }
+    input: {
+        console.log(function f() {
+            switch (f) {
+              case f:
+                return "PASS";
+              default:
+                return "FAIL";
+            }
+        }());
+    }
+    expect: {
+        console.log(function f() {
+            switch (f) {
+              default:
+                return "PASS";
+            }
+        }());
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5008_2: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        reduce_vars: true,
+        switches: true,
+        unsafe: true,
+    }
+    input: {
+        console.log(function(a) {
+            switch (a) {
+              case a:
+                return "PASS";
+              default:
+                return "FAIL";
+            }
+        }([]));
+    }
+    expect: {
+        console.log(function(a) {
+            switch (a) {
+              default:
+                return "PASS";
+            }
+        }([]));
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5008_3: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        reduce_vars: true,
+        switches: true,
+        unsafe: true,
+    }
+    input: {
+        console.log(function(a) {
+            switch (a) {
+              case a:
+                return "PASS";
+              default:
+                return "FAIL";
+            }
+        }({}));
+    }
+    expect: {
+        console.log(function(a) {
+            switch (a) {
+              default:
+                return "PASS";
+            }
+        }({}));
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5008_4: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        reduce_vars: true,
+        switches: true,
+    }
+    input: {
+        console.log(function(a) {
+            switch (a) {
+              case a:
+                return "PASS";
+              default:
+                return "FAIL";
+            }
+        }(/foo/));
+    }
+    expect: {
+        console.log(function(a) {
+            switch (a) {
+              default:
+                return "PASS";
+            }
+        }(/foo/));
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5010: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        var a;
+        switch (42) {
+          case console.log("PASS"):
+          case a:
+            console.log("FAIL");
+          case 42:
+        }
+    }
+    expect: {
+        var a;
+        switch (42) {
+          case console.log("PASS"):
+          case a:
+            console.log("FAIL");
+        }
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5012: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        switch (void 0) {
+          case console.log("PASS"):
+            break;
+          case void 0:
+          case 42:
+            console.log("FAIL");
+        }
+    }
+    expect: {
+        switch (void 0) {
+          case console.log("PASS"):
+            break;
+          default:
+            console.log("FAIL");
+        }
+    }
+    expect_stdout: "PASS"
+}

test/compress/yields.js

@@ -1083,3 +1083,166 @@ issue_4769_2: {
     expect_stdout: "PASS"
     node_version: ">=6"
 }
+
+issue_5019_1: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        (function(a) {
+            return a = function*() {
+                console.log(typeof a);
+            }();
+        })().next();
+    }
+    expect: {
+        (function(a) {
+            return a = function*() {
+                console.log(typeof a);
+            }();
+        })().next();
+    }
+    expect_stdout: "object"
+    node_version: ">=4"
+}
+
+issue_5019_2: {
+    options = {
+        inline: true,
+        toplevel: true,
+    }
+    input: {
+        var a = [];
+        for (var b in "foo")
+            a.push(function(c) {
+                return function*() {
+                    console.log(c);
+                }();
+            }(b));
+        a.map(function(d) {
+            return d.next();
+        });
+    }
+    expect: {
+        var a = [];
+        for (var b in "foo")
+            a.push(function(c) {
+                return function*() {
+                    console.log(c);
+                }();
+            }(b));
+        a.map(function(d) {
+            return d.next();
+        });
+    }
+    expect_stdout: [
+        "0",
+        "1",
+        "2",
+    ]
+    node_version: ">=4"
+}
+
+issue_5032_normal: {
+    options = {
+        merge_vars: true,
+        webkit: false,
+    }
+    input: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        function *f(a) {
+            var b = log(a), c = b;
+            log(b);
+            log(c);
+        }
+        f("PASS").next();
+    }
+    expect: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        function *f(c) {
+            var b = log(c), c = b;
+            log(b);
+            log(c);
+        }
+        f("PASS").next();
+    }
+    expect_stdout: [
+        "PASS",
+        "PASS",
+        "PASS",
+    ]
+    node_version: ">=4"
+}
+
+issue_5032_webkit: {
+    options = {
+        merge_vars: true,
+        webkit: true,
+    }
+    input: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        function *f(a) {
+            var b = log(a), c = b;
+            log(b);
+            log(c);
+        }
+        f("PASS").next();
+    }
+    expect: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        function *f(a) {
+            var b = log(a), c = b;
+            log(b);
+            log(c);
+        }
+        f("PASS").next();
+    }
+    expect_stdout: [
+        "PASS",
+        "PASS",
+        "PASS",
+    ]
+    node_version: ">=4"
+}
+
+issue_5034: {
+    options = {
+        functions: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function() {
+            var yield = function f() {
+                return function*() {
+                    return f;
+                };
+            };
+            return yield()().next().value === yield;
+        }() ? "PASS" : "FAIL");
+    }
+    expect: {
+        console.log(function() {
+            var yield = function f() {
+                return function*() {
+                    return f;
+                };
+            };
+            return yield()().next().value === yield;
+        }() ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}

test/release/rollup-ts.sh

@@ -43,6 +43,9 @@ rm -rf tmp/rollup \
 -    "postpublish": "pinst --enable",
 -    "prepare": "npm run build",
 -    "prepublishOnly": "pinst --disable && npm ci && npm run lint:nofix && npm run security && npm run build:bootstrap && npm run test:all",
+@@ -93 +89 @@
+-    "is-reference": "lukastaegert/is-reference#update-class-features",
++    "is-reference": "3.0.0",
 --- a/test/cli/index.js
 +++ b/test/cli/index.js
 @@ -13,0 +14,3 @@ sander.rimrafSync(__dirname, 'node_modules');