enhance `compress` on arrow and `async` functions (#4616)

1 files changed, 7 insertions, 7 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 781b59f3..d4cf0da9 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1843,7 +1843,7 @@ merge(Compressor.prototype, {
                 if (node instanceof AST_Call) {
                     if (!(lhs instanceof AST_PropAccess)) return false;
                     if (!lhs.equivalent_to(node.expression)) return false;
-                    return !(rvalue instanceof AST_Function && !rvalue.contains_this());
+                    return !(is_function(rvalue) && !rvalue.contains_this());
                 }
                 if (node instanceof AST_Debugger) return true;
                 if (node instanceof AST_Defun) return funarg && lhs.name === node.name.name;
@@ -2482,7 +2482,7 @@ merge(Compressor.prototype, {
                         if (modify_toplevel) return;
                         var exp = node.expression;
                         if (exp instanceof AST_PropAccess) return;
-                        if (exp instanceof AST_Function && !exp.contains_this()) return;
+                        if (is_function(exp) && !exp.contains_this()) return;
                         modify_toplevel = true;
                     } else if (node instanceof AST_PropAccess && may_be_global(node.expression)) {
                         if (node === lhs && !(expr instanceof AST_Unary)) {
@@ -4060,7 +4060,7 @@ merge(Compressor.prototype, {
                         key = key._eval(compressor, ignore_side_effects, cached, depth);
                         if (key === prop.key) return this;
                     }
-                    if (prop.value instanceof AST_Function && typeof Object.prototype[key] == "function") return this;
+                    if (key == "toString" || key == "valueOf") return this;
                     val[key] = prop.value._eval(compressor, ignore_side_effects, cached, depth);
                     if (val[key] === prop.value) return this;
                 }
@@ -5850,10 +5850,10 @@ merge(Compressor.prototype, {
                             }
                         } else if (compressor.option("functions")
                             && !compressor.option("ie8")
-                            && !(node instanceof AST_Const || node instanceof AST_Let)
+                            && node instanceof AST_Var
                             && var_defs[sym.id] == 1
                             && sym.assignments == 0
-                            && value instanceof AST_Function
+                            && (value instanceof AST_AsyncFunction || value instanceof AST_Function)
                             && (sym.references.length ? all(sym.references, function(ref) {
                                     return value === ref.fixed_value();
                                 }) : value === def.name.fixed_value())
@@ -5864,7 +5864,7 @@ merge(Compressor.prototype, {
                             && can_declare_defun()
                             && can_rename(value, def.name.name)) {
                             AST_Node.warn("Declaring {name} as function [{file}:{line},{col}]", template(def.name));
-                            var defun = make_node(AST_Defun, def, value);
+                            var defun = make_node(value instanceof AST_Function ? AST_Defun : AST_AsyncDefun, def, value);
                             defun.name = make_node(AST_SymbolDefun, def.name, def.name);
                             var name_def = def.name.scope.resolve().def_function(defun.name);
                             if (old_def) old_def.forEach(function(node) {
@@ -6902,7 +6902,7 @@ merge(Compressor.prototype, {
                 return exprs && make_sequence(self, exprs.map(convert_spread));
             }
             var def;
-            if (exp instanceof AST_Function
+            if ((is_arrow(exp) && !exp.value || exp instanceof AST_AsyncFunction || exp instanceof AST_Function)
                 && !(exp.name && (def = exp.name.definition()).references.length > def.replaced)) {
                 exp.process_expression(false, function(node) {
                     var value = node.value && node.value.drop_side_effect_free(compressor, true);