inline property access of object literal (#2209)

- only if property value is side-effect-free
- guard by `unsafe`

fixes #2208

lib/compress.js

@@ -4307,6 +4307,17 @@ merge(Compressor.prototype, {
         return self;
     });
 
+    AST_Lambda.DEFMETHOD("contains_this", function() {
+        var result;
+        var self = this;
+        self.walk(new TreeWalker(function(node) {
+            if (result) return true;
+            if (node instanceof AST_This) return result = true;
+            if (node !== self && node instanceof AST_Scope) return true;
+        }));
+        return result;
+    });
+
     OPT(AST_Dot, function(self, compressor){
         var def = self.resolve_defines(compressor);
         if (def) {
@@ -4321,6 +4332,20 @@ merge(Compressor.prototype, {
                 })
             }).optimize(compressor);
         }
+        if (compressor.option("unsafe") && self.expression instanceof AST_Object) {
+            var values = self.expression.properties;
+            for (var i = values.length; --i >= 0;) {
+                if (values[i].key === prop) {
+                    var value = values[i].value;
+                    if (value instanceof AST_Function ? !value.contains_this() : !value.has_side_effects(compressor)) {
+                        var obj = self.expression.clone();
+                        obj.properties = obj.properties.slice();
+                        obj.properties.splice(i, 1);
+                        return make_sequence(self, [ obj, value ]).optimize(compressor);
+                    }
+                }
+            }
+        }
         if (compressor.option("unsafe_proto")
             && self.expression instanceof AST_Dot
             && self.expression.property == "prototype") {

test/compress/evaluate.js

@@ -250,22 +250,26 @@ unsafe_constant: {
 
 unsafe_object: {
     options = {
-        evaluate  : true,
+        evaluate: true,
-        unsafe    : true
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
     }
     input: {
+        var o = { a: 1 };
         console.log(
-            ({a:1}) + 1,
+            o + 1,
-            ({a:1}).a + 1,
+            o.a + 1,
-            ({a:1}).b + 1,
+            o.b + 1,
-            ({a:1}).a.b + 1
+            o.a.b + 1
         );
     }
     expect: {
+        var o = { a: 1 };
         console.log(
-            ({a:1}) + 1,
+            o + 1,
             2,
-            ({a:1}).b + 1,
+            o.b + 1,
             1..b + 1
         );
     }
@@ -274,22 +278,26 @@ unsafe_object: {
 
 unsafe_object_nested: {
     options = {
-        evaluate  : true,
+        evaluate: true,
-        unsafe    : true
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
     }
     input: {
+        var o = { a: { b: 1 } };
         console.log(
-            ({a:{b:1}}) + 1,
+            o + 1,
-            ({a:{b:1}}).a + 1,
+            o.a + 1,
-            ({a:{b:1}}).b + 1,
+            o.b + 1,
-            ({a:{b:1}}).a.b + 1
+            o.a.b + 1
         );
     }
     expect: {
+        var o = { a: { b: 1 } };
         console.log(
-            ({a:{b:1}}) + 1,
+            o + 1,
-            ({a:{b:1}}).a + 1,
+            o.a + 1,
-            ({a:{b:1}}).b + 1,
+            o.b + 1,
             2
         );
     }
@@ -298,21 +306,25 @@ unsafe_object_nested: {
 
 unsafe_object_complex: {
     options = {
-        evaluate  : true,
+        evaluate: true,
-        unsafe    : true
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
     }
     input: {
+        var o = { a: { b: 1 }, b: 1 };
         console.log(
-            ({a:{b:1},b:1}) + 1,
+            o + 1,
-            ({a:{b:1},b:1}).a + 1,
+            o.a + 1,
-            ({a:{b:1},b:1}).b + 1,
+            o.b + 1,
-            ({a:{b:1},b:1}).a.b + 1
+            o.a.b + 1
         );
     }
     expect: {
+        var o = { a: { b: 1 }, b: 1 };
         console.log(
-            ({a:{b:1},b:1}) + 1,
+            o + 1,
-            ({a:{b:1},b:1}).a + 1,
+            o.a + 1,
             2,
             2
         );
@@ -322,22 +334,26 @@ unsafe_object_complex: {
 
 unsafe_object_repeated: {
     options = {
-        evaluate  : true,
+        evaluate: true,
-        unsafe    : true
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
     }
     input: {
+        var o = { a: { b: 1 }, a: 1 };
         console.log(
-            ({a:{b:1},a:1}) + 1,
+            o + 1,
-            ({a:{b:1},a:1}).a + 1,
+            o.a + 1,
-            ({a:{b:1},a:1}).b + 1,
+            o.b + 1,
-            ({a:{b:1},a:1}).a.b + 1
+            o.a.b + 1
         );
     }
     expect: {
+        var o = { a: { b: 1 }, a: 1 };
         console.log(
-            ({a:{b:1},a:1}) + 1,
+            o + 1,
             2,
-            ({a:{b:1},a:1}).b + 1,
+            o.b + 1,
             1..b + 1
         );
     }
@@ -386,9 +402,9 @@ unsafe_function: {
     expect: {
         console.log(
             ({a:{b:1},b:function(){}}) + 1,
-            ({a:{b:1},b:function(){}}).a + 1,
+            ({b:function(){}}, {b:1}) + 1,
-            ({a:{b:1},b:function(){}}).b + 1,
+            ({a:{b:1}}, function(){}) + 1,
-            ({a:{b:1},b:function(){}}).a.b + 1
+            ({b:function(){}}, {b:1}).b + 1
         );
     }
     expect_stdout: true
@@ -636,8 +652,8 @@ unsafe_prototype_function: {
         var d = ({toString: 0}) + "";
         var e = (({valueOf: 0}) + "")[2];
         var f = (({toString: 0}) + "")[2];
-        var g = ({valueOf: 0}).valueOf();
+        var g = ({}, 0)();
-        var h = "" + ({toString: 0});
+        var h = ({}, 0)();
     }
 }
 

test/compress/global_defs.js

@@ -37,6 +37,7 @@ object: {
                 VALUE: 42,
             },
         },
+        side_effects: true,
         unsafe: true,
     }
     input: {
@@ -140,9 +141,9 @@ mixed: {
         console.log(CONFIG);
     }
     expect_warnings: [
-        'WARN: global_defs CONFIG.VALUE redefined [test/compress/global_defs.js:126,22]',
         'WARN: global_defs CONFIG.VALUE redefined [test/compress/global_defs.js:127,22]',
-        'WARN: global_defs CONFIG.VALUE redefined [test/compress/global_defs.js:129,8]',
+        'WARN: global_defs CONFIG.VALUE redefined [test/compress/global_defs.js:128,22]',
+        'WARN: global_defs CONFIG.VALUE redefined [test/compress/global_defs.js:130,8]',
     ]
 }
 

test/compress/properties.js

@@ -657,3 +657,116 @@ accessor_this: {
     expect_exact: 'var a=1;var b={get this(){return a},set this(c){a=c}};console.log(b.this,b.this=2,b.this);'
     expect_stdout: "1 2 2"
 }
+
+issue_2208_1: {
+    options = {
+        inline: true,
+        side_effects: true,
+        unsafe: true,
+    }
+    input: {
+        console.log({
+            p: function() {
+                return 42;
+            }
+        }.p());
+    }
+    expect: {
+        console.log(42);
+    }
+    expect_stdout: "42"
+}
+
+issue_2208_2: {
+    options = {
+        inline: true,
+        side_effects: true,
+        unsafe: true,
+    }
+    input: {
+        console.log({
+            a: 42,
+            p: function() {
+                return this.a;
+            }
+        }.p());
+    }
+    expect: {
+        console.log({
+            a: 42,
+            p: function() {
+                return this.a;
+            }
+        }.p());
+    }
+    expect_stdout: "42"
+}
+
+issue_2208_3: {
+    options = {
+        inline: true,
+        side_effects: true,
+        unsafe: true,
+    }
+    input: {
+        a = 42;
+        console.log({
+            p: function() {
+                return function() {
+                    return this.a;
+                }();
+            }
+        }.p());
+    }
+    expect: {
+        a = 42;
+        console.log(function() {
+            return this.a;
+        }());
+    }
+    expect_stdout: "42"
+}
+
+issue_2208_4: {
+    options = {
+        inline: true,
+        side_effects: true,
+        unsafe: true,
+    }
+    input: {
+        function foo() {}
+        console.log({
+            a: foo(),
+            p: function() {
+                return 42;
+            }
+        }.p());
+    }
+    expect: {
+        function foo() {}
+        console.log((foo(), function() {
+            return 42;
+        })());
+    }
+    expect_stdout: "42"
+}
+
+issue_2208_5: {
+    options = {
+        inline: true,
+        side_effects: true,
+        unsafe: true,
+    }
+    input: {
+        console.log({
+            p: "FAIL",
+            p: function() {
+                return 42;
+            }
+        }.p());
+    }
+    expect: {
+        console.log(42);
+    }
+    expect_stdout: "42"
+}