compress undefined property names (#2811)

- enforce property names as string
- handle `void 0` as `undefined` in `hoist_props` & `reduce_vars`

lib/ast.js

@@ -689,8 +689,8 @@ var AST_Object = DEFNODE("Object", "properties", {
 var AST_ObjectProperty = DEFNODE("ObjectProperty", "key value", {
     $documentation: "Base class for literal object properties",
     $propdoc: {
-        key: "[string] the property name converted to a string for ObjectKeyVal.  For setters and getters this is an AST_SymbolAccessor.",
+        key: "[string|AST_SymbolAccessor] property name. For ObjectKeyVal this is a string. For getters and setters this is an AST_SymbolAccessor.",
-        value: "[AST_Node] property value.  For setters and getters this is an AST_Accessor."
+        value: "[AST_Node] property value.  For getters and setters this is an AST_Accessor."
     },
     _walk: function(visitor) {
         return visitor._visit(this, function(){

lib/compress.js

@@ -404,14 +404,15 @@ merge(Compressor.prototype, {
         }
 
         function read_property(obj, key) {
-            if (key instanceof AST_Constant) key = key.getValue();
+            key = get_value(key);
-            if (key instanceof AST_Node) return null;
+            if (key instanceof AST_Node) return;
             var value;
             if (obj instanceof AST_Array) {
                 var elements = obj.elements;
                 if (key == "length") return make_node_from_constant(elements.length, obj);
                 if (typeof key == "number" && key in elements) value = elements[key];
             } else if (obj instanceof AST_Object) {
+                key = "" + key;
                 var props = obj.properties;
                 for (var i = props.length; --i >= 0;) {
                     var prop = props[i];
@@ -1855,6 +1856,18 @@ merge(Compressor.prototype, {
         }));
     };
 
+    function get_value(key) {
+        if (key instanceof AST_Constant) {
+            return key.getValue();
+        }
+        if (key instanceof AST_UnaryPrefix
+            && key.operator == "void"
+            && key.expression instanceof AST_Constant) {
+            return;
+        }
+        return key;
+    }
+
     function is_undefined(node, compressor) {
         return node.is_undefined
             || node instanceof AST_Undefined
@@ -3295,9 +3308,7 @@ merge(Compressor.prototype, {
             if (node instanceof AST_PropAccess && node.expression instanceof AST_SymbolRef) {
                 var defs = defs_by_id[node.expression.definition().id];
                 if (defs) {
-                    var key = node.property;
+                    var def = defs.get(get_value(node.property));
-                    if (key instanceof AST_Node) key = key.getValue();
-                    var def = defs.get(key);
                     var sym = make_node(AST_SymbolRef, node, {
                         name: def.name,
                         scope: node.expression.scope,

lib/output.js

@@ -1349,11 +1349,8 @@ function OutputStream(options) {
 
     function print_property_name(key, quote, output) {
         if (output.option("quote_keys")) {
-            output.print_string(key + "");
+            output.print_string(key);
-        } else if ((typeof key == "number"
+        } else if ("" + +key == key && key >= 0) {
-                    || !output.option("beautify")
-                    && +key + "" == key)
-                   && parseFloat(key) >= 0) {
             output.print(make_num(key));
         } else if (RESERVED_WORDS(key) ? !output.option("ie8") : is_identifier_string(key)) {
             if (quote && output.option("keep_quoted_props")) {

lib/parse.js

@@ -1365,7 +1365,7 @@ function parse($TEXT, options) {
             if (type == "name" && !is("punc", ":")) {
                 var key = new AST_SymbolAccessor({
                     start: S.token,
-                    name: as_property_name(),
+                    name: "" + as_property_name(),
                     end: prev()
                 });
                 if (name == "get") {
@@ -1391,7 +1391,7 @@ function parse($TEXT, options) {
             a.push(new AST_ObjectKeyVal({
                 start : start,
                 quote : start.quote,
-                key   : name,
+                key   : "" + name,
                 value : expression(false),
                 end   : prev()
             }));

test/compress/hoist_props.js

@@ -664,3 +664,25 @@ issue_2519: {
     }
     expect_stdout: "5.5"
 }
+
+undefined_key: {
+    options = {
+        evaluate: true,
+        hoist_props: true,
+        join_vars: true,
+        passes: 4,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a, o = {};
+        o[a] = 1;
+        o.b = 2;
+        console.log(o[a] + o.b);
+    }
+    expect: {
+        console.log(3);
+    }
+    expect_stdout: "3"
+}

test/compress/issue-1770.js

@@ -84,12 +84,12 @@ numeric_literal: {
         '    0: 0,',
         '    "-0": 1,',
         '    42: 2,',
-        '    "42": 3,',
+        '    42: 3,',
         '    37: 4,',
         '    o: 5,',
         '    1e42: 6,',
         '    b: 7,',
-        '    "1e+42": 8',
+        '    1e42: 8',
         '};',
         '',
         'console.log(obj[-0], obj[-""], obj["-0"]);',