fix unsafe reduce_vars on arrays & objects (#2397)

lib/compress.js

@@ -567,18 +567,18 @@ merge(Compressor.prototype, {
         function read_property(obj, key) {
             if (key instanceof AST_Constant) key = key.getValue();
             if (key instanceof AST_Node) return null;
+            var value;
             if (obj instanceof AST_Array) {
-                return obj.elements[key];
+                value = obj.elements[key];
             } else if (obj instanceof AST_Object) {
                 var props = obj.properties;
-                var value;
                 for (var i = props.length; --i >= 0;) {
                     var prop = props[i];
                     if (!(prop instanceof AST_ObjectKeyVal)) return;
                     if (!value && props[i].key === key) value = props[i].value;
                 }
-                return value;
             }
+            return value instanceof AST_SymbolRef ? value.fixed_value() : value;
         }
 
         function is_modified(node, value, level, immutable) {
@@ -589,6 +589,8 @@ merge(Compressor.prototype, {
                     && parent.expression === node
                     && (!(value instanceof AST_Function) || value.contains_this())) {
                 return true;
+            } else if (parent instanceof AST_Array || parent instanceof AST_Object) {
+                return is_modified(parent, parent, level + 1);
             } else if (parent instanceof AST_PropAccess && parent.expression === node) {
                 return !immutable && is_modified(parent, read_property(value, parent.property), level + 1);
             }
@@ -602,6 +604,8 @@ merge(Compressor.prototype, {
                 || parent instanceof AST_Return && node === parent.value && node.scope !== d.scope
                 || parent instanceof AST_VarDef && node === parent.value) {
                 d.escaped = true;
+            } else if (parent instanceof AST_Array || parent instanceof AST_Object) {
+                mark_escaped(d, parent, parent, level + 1);
             } else if (parent instanceof AST_PropAccess && node === parent.expression) {
                 mark_escaped(d, parent, read_property(value, parent.property), level + 1);
             }

test/compress/reduce_vars.js

@@ -211,7 +211,7 @@ unsafe_evaluate: {
     }
 }
 
-unsafe_evaluate_side_effect_free: {
+unsafe_evaluate_side_effect_free_1: {
     options = {
         evaluate: true,
         reduce_vars: true,
@@ -221,10 +221,31 @@ unsafe_evaluate_side_effect_free: {
     input: {
         console.log(function(){ var o={p:1}; console.log(o.p); return o.p; }());
         console.log(function(){ var o={p:2}; console.log(o.p); return o; }());
+        console.log(function(){ var o={p:3}; console.log([o][0].p); return o.p; }());
     }
     expect: {
         console.log(function(){ console.log(1); return 1; }());
         console.log(function(){ var o={p:2}; console.log(2); return o; }());
+        console.log(function(){ console.log(3); return 3; }());
+    }
+    expect_stdout: true
+}
+
+unsafe_evaluate_side_effect_free_2: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+        passes: 2,
+        pure_getters: "strict",
+        reduce_vars: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        console.log(function(){ var o={p:1},a=[o]; console.log(a[0].p); return o.p; }());
+    }
+    expect: {
+        console.log(function(){ console.log(1); return 1; }());
     }
     expect_stdout: true
 }
@@ -239,10 +260,12 @@ unsafe_evaluate_escaped: {
     input: {
         console.log(function(){ var o={p:1}; console.log(o, o.p); return o.p; }());
         console.log(function(){ var o={p:2}; console.log(o.p, o); return o.p; }());
+        console.log(function(){ var o={p:3},a=[o]; console.log(a[0].p++); return o.p; }());
     }
     expect: {
         console.log(function(){ var o={p:1}; console.log(o, o.p); return o.p; }());
         console.log(function(){ var o={p:2}; console.log(o.p, o); return o.p; }());
+        console.log(function(){ var o={p:3},a=[o]; console.log(a[0].p++); return o.p; }());
     }
     expect_stdout: true
 }
@@ -262,6 +285,7 @@ unsafe_evaluate_modified: {
         console.log(function(){ var o={p:5}; o.p = -9; console.log(o.p); return o.p; }());
         function inc() { this.p++; }
         console.log(function(){ var o={p:6}; inc.call(o); console.log(o.p); return o.p; }());
+        console.log(function(){ var o={p:7}; console.log([o][0].p++); return o.p; }());
     }
     expect: {
         console.log(function(){ var o={p:1}; o.p++; console.log(o.p); return o.p; }());
@@ -271,6 +295,7 @@ unsafe_evaluate_modified: {
         console.log(function(){ var o={p:5}; o.p = -9; console.log(o.p); return o.p; }());
         function inc() { this.p++; }
         console.log(function(){ var o={p:6}; inc.call(o); console.log(o.p); return o.p; }());
+        console.log(function(){ var o={p:7}; console.log([o][0].p++); return o.p; }());
     }
     expect_stdout: true
 }