From 766fafda8baefe6d150df27dfad7e99857c08557 Mon Sep 17 00:00:00 2001
From: Anthony Van de Gejuchte <anthonyvdgent@gmail.com>
Date: Tue, 19 Jul 2016 18:03:08 +0200
Subject: [PATCH] Don't remove empty generators passed as parameter

---
 lib/compress.js        |  1 +
 test/compress/yield.js | 26 ++++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/lib/compress.js b/lib/compress.js
index 21ec8e5c..21d8b50b 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -2282,6 +2282,7 @@ merge(Compressor.prototype, {
         }
         if (compressor.option("side_effects")) {
             if (self.expression instanceof AST_Function
+                && !self.expression.is_generator
                 && self.args.length == 0
                 && !AST_Block.prototype.has_side_effects.call(self.expression, compressor)) {
                 return make_node(AST_Undefined, self).transform(compressor);
diff --git a/test/compress/yield.js b/test/compress/yield.js
index 9fe9f6c8..c29ce926 100644
--- a/test/compress/yield.js
+++ b/test/compress/yield.js
@@ -139,4 +139,30 @@ yield_as_identifier_outside_strict_mode: {
         var yield = "foo";
         class yield {}
     }
+}
+
+empty_generator_as_parameter_with_side_effects: {
+    options = {
+        side_effects: true
+    }
+    input: {
+        var GeneratorPrototype = Object.getPrototypeOf(
+          Object.getPrototypeOf(function*() {}())
+        );
+        evaluate(GeneratorPrototype);
+    }
+    expect_exact: "var GeneratorPrototype=Object.getPrototypeOf(Object.getPrototypeOf(function*(){}()));evaluate(GeneratorPrototype);"
+}
+
+empty_generator_as_parameter_without_side_effects: {
+    options = {
+        side_effects: false
+    }
+    input: {
+        var GeneratorPrototype = Object.getPrototypeOf(
+          Object.getPrototypeOf(function*() {}())
+        );
+        evaluate(GeneratorPrototype);
+    }
+    expect_exact: "var GeneratorPrototype=Object.getPrototypeOf(Object.getPrototypeOf(function*(){}()));evaluate(GeneratorPrototype);"
 }
\ No newline at end of file