safer `properties` transform (#2391)

`{ a: x, b: y }.a` => `[ x, y ][0]`
- `x` cannot be function containing `this`

`[ x, y, z ][1]` => `(x, z, y)`
- only if `z` is side-effect-free

5 files changed, 150 insertions, 90 deletions

diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index 52b2ddf8..1f702ad7 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -2534,73 +2534,6 @@ 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",
-    ]
-}
-
 issue_2365: {
     options = {
         collapse_vars: true,
diff --git a/test/compress/evaluate.js b/test/compress/evaluate.js
index 5f5a4a93..fe9464bc 100644
--- a/test/compress/evaluate.js
+++ b/test/compress/evaluate.js
@@ -386,10 +386,10 @@ unsafe_object_accessor: {
     }
 }
 
-unsafe_function: {
+prop_function: {
     options = {
-        evaluate  : true,
-        unsafe    : true
+        evaluate: true,
+        properties: true,
     }
     input: {
         console.log(
@@ -402,9 +402,9 @@ unsafe_function: {
     expect: {
         console.log(
             ({a:{b:1},b:function(){}}) + 1,
-            ({b:function(){}}, {b:1}) + 1,
-            ({a:{b:1}}, function(){}) + 1,
-            ({b:function(){}}, {b:1}).b + 1
+            ({b:1}) + 1,
+            function(){} + 1,
+            2
         );
     }
     expect_stdout: true
@@ -630,10 +630,10 @@ unsafe_string_bad_index: {
     expect_stdout: true
 }
 
-unsafe_prototype_function: {
+prototype_function: {
     options = {
-        evaluate  : true,
-        unsafe    : true
+        evaluate: true,
+        properties: true,
     }
     input: {
         var a = ({valueOf: 0}) < 1;
@@ -652,8 +652,8 @@ unsafe_prototype_function: {
         var d = ({toString: 0}) + "";
         var e = (({valueOf: 0}) + "")[2];
         var f = (({toString: 0}) + "")[2];
-        var g = ({}, 0)();
-        var h = ({}, 0)();
+        var g = 0();
+        var h = 0();
     }
 }
 
diff --git a/test/compress/functions.js b/test/compress/functions.js
index 6c82557d..febf81c1 100644
--- a/test/compress/functions.js
+++ b/test/compress/functions.js
@@ -153,10 +153,10 @@ function_returning_constant_literal: {
     options = {
         inline: true,
         passes: 2,
+        properties: true,
         reduce_vars: true,
         side_effects: true,
         toplevel: true,
-        unsafe: true,
         unused: true,
     }
     input: {
diff --git a/test/compress/properties.js b/test/compress/properties.js
index 496a43ca..f435d371 100644
--- a/test/compress/properties.js
+++ b/test/compress/properties.js
@@ -677,8 +677,8 @@ accessor_this: {
 issue_2208_1: {
     options = {
         inline: true,
+        properties: true,
         side_effects: true,
-        unsafe: true,
     }
     input: {
         console.log({
@@ -696,8 +696,8 @@ issue_2208_1: {
 issue_2208_2: {
     options = {
         inline: true,
+        properties: true,
         side_effects: true,
-        unsafe: true,
     }
     input: {
         console.log({
@@ -721,8 +721,8 @@ issue_2208_2: {
 issue_2208_3: {
     options = {
         inline: true,
+        properties: true,
         side_effects: true,
-        unsafe: true,
     }
     input: {
         a = 42;
@@ -746,8 +746,8 @@ issue_2208_3: {
 issue_2208_4: {
     options = {
         inline: true,
+        properties: true,
         side_effects: true,
-        unsafe: true,
     }
     input: {
         function foo() {}
@@ -770,8 +770,8 @@ issue_2208_4: {
 issue_2208_5: {
     options = {
         inline: true,
+        properties: true,
         side_effects: true,
-        unsafe: true,
     }
     input: {
         console.log({
@@ -808,7 +808,7 @@ issue_2256: {
 lhs_prop_1: {
     options = {
         evaluate: true,
-        unsafe: true,
+        properties: true,
     }
     input: {
         console.log(++{
@@ -827,9 +827,9 @@ lhs_prop_2: {
     options = {
         evaluate: true,
         inline: true,
+        properties: true,
         reduce_vars: true,
         side_effects: true,
-        unsafe: true,
         unused: true,
     }
     input: {
@@ -844,7 +844,7 @@ lhs_prop_2: {
 
 literal_duplicate_key_side_effects: {
     options = {
-        unsafe: true,
+        properties: true,
     }
     input: {
         console.log({
@@ -853,10 +853,137 @@ literal_duplicate_key_side_effects: {
         }.a);
     }
     expect: {
+        console.log(console.log ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+}
+
+prop_side_effects_1: {
+    options = {
+        evaluate: true,
+        inline: true,
+        properties: true,
+        reduce_vars: true,
+        toplevel: 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);
+        var obj = {
+            bar: function() {
+                return 2;
+            }
+        };
+        console.log(obj.bar());
+    }
+    expect_stdout: [
+        "1",
+        "2",
+    ]
+}
+
+prop_side_effects_2: {
+    options = {
+        evaluate: true,
+        inline: true,
+        passes: 2,
+        properties: true,
+        reduce_vars: true,
+        toplevel: 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",
+    ]
+}
+
+accessor_1: {
+    options = {
+        properties: true,
+    }
+    input: {
+        console.log({
+            a: "FAIL",
+            get a() {
+                return "PASS";
+            }
+        }.a);
+    }
+    expect: {
         console.log({
             a: "FAIL",
-            a: console.log ? "PASS" : "FAIL"
+            get a() {
+                return "PASS";
+            }
         }.a);
     }
     expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+accessor_2: {
+    options = {
+        properties: true,
+    }
+    input: {
+        console.log({
+            get a() {
+                return "PASS";
+            },
+            set a(v) {},
+            a: "FAIL"
+        }.a);
+    }
+    expect: {
+        console.log({
+            get a() {
+                return "PASS";
+            },
+            set a(v) {},
+            a: "FAIL"
+        }.a);
+    }
+    expect_stdout: true
+}
+
+array_hole: {
+    options = {
+        properties: true,
+    }
+    input: {
+        console.log(
+            [ 1, 2, , 3][1],
+            [ 1, 2, , 3][2],
+            [ 1, 2, , 3][3]
+        );
+    }
+    expect: {
+        console.log(2, void 0, 3);
+    }
+    expect_stdout: "2 undefined 3"
 }
diff --git a/test/compress/reduce_vars.js b/test/compress/reduce_vars.js
index 681dafd3..1274024f 100644
--- a/test/compress/reduce_vars.js
+++ b/test/compress/reduce_vars.js
@@ -2660,8 +2660,8 @@ obj_var_2: {
         evaluate: true,
         inline: true,
         passes: 2,
+        properties: true,
         reduce_vars: true,
-        side_effects: true,
         toplevel: true,
         unsafe: true,
         unused: true,
@@ -2716,10 +2716,10 @@ obj_arg_2: {
         evaluate: true,
         inline: true,
         passes: 2,
+        properties: true,
         reduce_vars: true,
         side_effects: true,
         toplevel: true,
-        unsafe: true,
         unused: true,
     }
     input: {