From 850ab84495913196f2d26c20ccd54b8bb82bb78e Mon Sep 17 00:00:00 2001
From: kzc <zaxxon2011@gmail.com>
Date: Wed, 22 Nov 2017 21:57:14 -0500
Subject: [PATCH] optimize elements in array literal before spread

---
 lib/compress.js          |  4 +--
 test/compress/harmony.js | 77 +++++++++++++++++++++++++++++++++++++---
 2 files changed, 74 insertions(+), 7 deletions(-)

diff --git a/lib/compress.js b/lib/compress.js
index 9a2ceeb9..8a6a5f25 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -5000,9 +5000,7 @@ merge(Compressor.prototype, {
                 var flatten = true;
                 var values = [];
                 for (var i = elements.length; --i > index;) {
-                    var value = elements[i];
-                    if (value instanceof AST_Expansion) break FLATTEN;
-                    var value = value.drop_side_effect_free(compressor);
+                    var value = elements[i].drop_side_effect_free(compressor);
                     if (value) {
                         values.unshift(value);
                         if (flatten && value.has_side_effects(compressor)) flatten = false;
diff --git a/test/compress/harmony.js b/test/compress/harmony.js
index c197ddb5..ded16f09 100644
--- a/test/compress/harmony.js
+++ b/test/compress/harmony.js
@@ -1009,7 +1009,7 @@ array_literal_with_spread_2: {
     }
     expect: {
         console.log([ 10, ...[], 20, ...[ 30, 40 ], 50 ]["length"]);
-        console.log([ 10, ...[], 20, ...[ 30, 40 ], 50 ][0]);
+        console.log(10);
         console.log([ 10, ...[], 20, ...[ 30, 40 ], 50 ][1]);
         console.log([ 10, ...[], 20, ...[ 30, 40 ], 50 ][2]);
         console.log([ 10, ...[], 20, ...[ 30, 40 ], 50 ][3]);
@@ -1059,12 +1059,12 @@ array_literal_with_spread_3: {
         console.log([...[], 10, 20][1]);
         console.log([...[], 10, 20][2]);
 
-        console.log([10, ...[], 20][0]);
+        console.log(10);
         console.log([10, ...[], 20][1]);
         console.log([10, ...[], 20][2]);
 
-        console.log([10, 20, ...[]][0]);
-        console.log([10, 20, ...[]][1]);
+        console.log(10);
+        console.log(20);
         console.log([10, 20, ...[]][2]);
     }
     expect_stdout: [
@@ -1083,3 +1083,72 @@ array_literal_with_spread_3: {
     ]
     node_version: ">=6"
 }
+
+array_literal_with_spread_4: {
+    options = {
+        properties: true,
+        side_effects: true,
+    }
+    input: {
+        function t(x) {
+            console.log("(" + x + ")");
+            return 10 * x;
+        }
+
+        console.log([t(1), t(2)][0]);
+        console.log([t(1), t(2)][1]);
+        console.log([t(1), t(2)][2]);
+
+        console.log([...[], t(1), t(2)][0]);
+        console.log([...[], t(1), t(2)][1]);
+        console.log([...[], t(1), t(2)][2]);
+
+        console.log([t(1), ...[], t(2)][0]);
+        console.log([t(1), ...[], t(2)][1]);
+        console.log([t(1), ...[], t(2)][2]);
+
+        console.log([t(1), t(2), ...[]][0]);
+        console.log([t(1), t(2), ...[]][1]);
+        console.log([t(1), t(2), ...[]][2]);
+    }
+    expect: {
+        function t(x) {
+            console.log("(" + x + ")");
+            return 10 * x;
+        }
+
+        console.log([ t(1), t(2) ][0]);
+        console.log((t(1), t(2)));
+        console.log([ t(1), t(2) ][2]);
+
+        console.log([ ...[], t(1), t(2) ][0]);
+        console.log([ ...[], t(1), t(2) ][1]);
+        console.log([ ...[], t(1), t(2) ][2]);
+
+        console.log([ t(1), t(2) ][0]);
+        console.log([ t(1), ...[], t(2) ][1]);
+        console.log([ t(1), ...[], t(2) ][2]);
+
+        console.log([ t(1), t(2) ][0]);
+        console.log((t(1), t(2)));
+        console.log([ t(1), t(2), ...[] ][2]);
+    }
+    expect_stdout: [
+        "(1)", "(2)", "10",
+        "(1)", "(2)", "20",
+        "(1)", "(2)", "undefined",
+
+        "(1)", "(2)", "10",
+        "(1)", "(2)", "20",
+        "(1)", "(2)", "undefined",
+
+        "(1)", "(2)", "10",
+        "(1)", "(2)", "20",
+        "(1)", "(2)", "undefined",
+
+        "(1)", "(2)", "10",
+        "(1)", "(2)", "20",
+        "(1)", "(2)", "undefined",
+    ]
+    node_version: ">=6"
+}