compress `arguments[index]` (#2967)

- always replace with existing parameter
- only introduce new parameter if `keep_fargs` is disabled

2 files changed, 125 insertions, 6 deletions

diff --git a/test/compress/arguments.js b/test/compress/arguments.js
new file mode 100644
index 00000000..e8cc690f
--- /dev/null
+++ b/test/compress/arguments.js
@@ -0,0 +1,119 @@
+replace_index: {
+    options = {
+        arguments: true,
+        evaluate: true,
+        properties: true,
+    }
+    input: {
+        console.log(arguments && arguments[0]);
+        (function() {
+            console.log(arguments[1], arguments["1"], arguments["foo"]);
+        })("bar", 42);
+        (function(a, b) {
+            console.log(arguments[1], arguments["1"], arguments["foo"]);
+        })("bar", 42);
+        (function(arguments) {
+            console.log(arguments[1], arguments["1"], arguments["foo"]);
+        })("bar", 42);
+        (function() {
+            var arguments;
+            console.log(arguments[1], arguments["1"], arguments["foo"]);
+        })("bar", 42);
+    }
+    expect: {
+        console.log(arguments && arguments[0]);
+        (function() {
+            console.log(arguments[1], arguments[1], arguments.foo);
+        })("bar", 42);
+        (function(a, b) {
+            console.log(b, b, arguments.foo);
+        })("bar", 42);
+        (function(arguments) {
+            console.log(arguments[1], arguments[1], arguments.foo);
+        })("bar", 42);
+        (function() {
+            var arguments;
+            console.log(arguments[1], arguments[1], arguments.foo);
+        })("bar", 42);
+    }
+    expect_stdout: [
+        "undefined",
+        "42 42 undefined",
+        "42 42 undefined",
+        "a a undefined",
+        "42 42 undefined",
+    ]
+}
+
+replace_index_keep_fargs: {
+    options = {
+        arguments: true,
+        evaluate: true,
+        keep_fargs: false,
+        properties: true,
+    }
+    input: {
+        console.log(arguments && arguments[0]);
+        (function() {
+            console.log(arguments[1], arguments["1"], arguments["foo"]);
+        })("bar", 42);
+        (function(a, b) {
+            console.log(arguments[1], arguments["1"], arguments["foo"]);
+        })("bar", 42);
+        (function(arguments) {
+            console.log(arguments[1], arguments["1"], arguments["foo"]);
+        })("bar", 42);
+        (function() {
+            var arguments;
+            console.log(arguments[1], arguments["1"], arguments["foo"]);
+        })("bar", 42);
+    }
+    expect: {
+        console.log(arguments && arguments[0]);
+        (function(argument_0, argument_1) {
+            console.log(argument_1, argument_1, arguments.foo);
+        })("bar", 42);
+        (function(a, b) {
+            console.log(b, b, arguments.foo);
+        })("bar", 42);
+        (function(arguments) {
+            console.log(arguments[1], arguments[1], arguments.foo);
+        })("bar", 42);
+        (function() {
+            var arguments;
+            console.log(arguments[1], arguments[1], arguments.foo);
+        })("bar", 42);
+    }
+    expect_stdout: [
+        "undefined",
+        "42 42 undefined",
+        "42 42 undefined",
+        "a a undefined",
+        "42 42 undefined",
+    ]
+}
+
+modified: {
+    options = {
+        arguments: true,
+    }
+    input: {
+        (function(a, b) {
+            var c = arguments[0];
+            var d = arguments[1];
+            a = "foo";
+            b++;
+            console.log(a, b, c, d, arguments[0], arguments[1]);
+        })("bar", 42);
+    }
+    expect: {
+        (function(a, b) {
+            var c = a;
+            var d = b;
+            a = "foo";
+            b++;
+            console.log(a, b, c, d, a, b);
+        })("bar", 42);
+    }
+    expect_stdout: "foo 43 bar 42 foo 43"
+}
diff --git a/test/compress/hoist_props.js b/test/compress/hoist_props.js
index 03867f78..26887af2 100644
--- a/test/compress/hoist_props.js
+++ b/test/compress/hoist_props.js
@@ -239,14 +239,14 @@ name_collision_2: {
     input: {
         var o = {
             p: 1,
-            0: function(x) {
+            "+": function(x) {
                 return x;
             },
-            1: function(x) {
+            "-": function(x) {
                 return x + 1;
             }
         }, o__$0 = 2, o__$1 = 3;
-        console.log(o.p === o.p, o[0](4), o[1](5), o__$0, o__$1);
+        console.log(o.p === o.p, o["+"](4), o["-"](5), o__$0, o__$1);
     }
     expect: {
         var o_p = 1,
@@ -273,14 +273,14 @@ name_collision_3: {
     input: {
         var o = {
             p: 1,
-            0: function(x) {
+            "+": function(x) {
                 return x;
             },
-            1: function(x) {
+            "-": function(x) {
                 return x + 1;
             }
         }, o__$0 = 2, o__$1 = 3;
-        console.log(o.p === o.p, o[0](4), o[1](5));
+        console.log(o.p === o.p, o["+"](4), o["-"](5));
     }
     expect: {
         var o_p = 1,