enhance `inline`, `sequences` & `side_effects` (#4493)

1 files changed, 14 insertions, 1 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 5f8f3736..0a46fb26 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -8018,7 +8018,7 @@ merge(Compressor.prototype, {
             }
         }
         var fn = exp instanceof AST_SymbolRef ? exp.fixed_value() : exp;
-        var is_func = fn instanceof AST_Arrow || fn instanceof AST_Defun || fn instanceof AST_Function;
+        var is_func = fn instanceof AST_Lambda && (!is_async(fn) || compressor.parent() instanceof AST_Await);
         var stat = is_func && fn.first_statement();
         var has_default = false;
         var can_drop = is_func && all(fn.argnames, function(argname, index) {
@@ -8649,6 +8649,19 @@ merge(Compressor.prototype, {
             ? self : try_evaluate(compressor, self);
     });
 
+    OPT(AST_Await, function(self, compressor) {
+        if (compressor.option("sequences")) {
+            var seq = lift_sequence_in_expression(self, compressor);
+            if (seq !== self) return seq.optimize(compressor);
+        }
+        if (compressor.option("side_effects")) {
+            var exp = self.expression;
+            if (exp instanceof AST_Await) return exp;
+            if (exp instanceof AST_UnaryPrefix && exp.expression instanceof AST_Await) return exp;
+        }
+        return self;
+    });
+
     AST_Binary.DEFMETHOD("lift_sequences", function(compressor) {
         if (this.left instanceof AST_PropAccess) {
             if (!(this.left.expression instanceof AST_Sequence)) return this;