From 1abe14296e9a11d30935dba3f27682a3e67885f8 Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Sun, 8 Oct 2017 13:17:48 +0800
Subject: [PATCH] collapse `a.b` whenever safe (#2350)

---
 lib/compress.js                |  2 +-
 test/compress/collapse_vars.js | 71 +++++++++++++++++++++++++++++++++-
 2 files changed, 70 insertions(+), 3 deletions(-)

diff --git a/lib/compress.js b/lib/compress.js
index d4a72d74..33b4ef00 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -812,7 +812,7 @@ merge(Compressor.prototype, {
                         var sym;
                         if (node instanceof AST_Call
                             || node instanceof AST_Exit
-                            || node instanceof AST_PropAccess
+                            || node instanceof AST_PropAccess && node.has_side_effects(compressor)
                             || node instanceof AST_SymbolRef
                                && (lvalues[node.name]
                                    || side_effects && !references_in_scope(node.definition()))
diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index ecd18610..631f5b29 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -1834,9 +1834,9 @@ issue_1858: {
     }
     expect: {
         console.log(function(x) {
-            var a = {}, b = a.b = x;
+            var a = {}, b = a.b = 1;
             return a.b + b;
-        }(1));
+        }());
     }
     expect_stdout: "2"
 }
@@ -2521,3 +2521,70 @@ issue_2319_3: {
     }
     expect_stdout: "true"
 }
+
+prop_side_effects_1: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        var C = 1;
+        console.log(C);
+        var obj = {
+            bar: function() {
+                return C + C;
+            }
+        };
+        console.log(obj.bar());
+    }
+    expect: {
+        console.log(1);
+        console.log({
+            bar: function() {
+                return 2;
+            }
+        }.bar());
+    }
+    expect_stdout: [
+        "1",
+        "2",
+    ]
+}
+
+prop_side_effects_2: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+        inline: true,
+        passes: 2,
+        pure_getters: "strict",
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        var C = 1;
+        console.log(C);
+        var obj = {
+            bar: function() {
+                return C + C;
+            }
+        };
+        console.log(obj.bar());
+    }
+    expect: {
+        console.log(1);
+        console.log(2);
+    }
+    expect_stdout: [
+        "1",
+        "2",
+    ]
+}
-- 
2.34.1