replace single-use class definitions (#2524)

fixes #2416

lib/ast.js

@@ -908,7 +908,7 @@ var AST_ConciseMethod = DEFNODE("ConciseMethod", "quote static is_generator asyn
     $documentation: "An ES6 concise method inside an object or class"
 }, AST_ObjectProperty);
 
-var AST_Class = DEFNODE("Class", "name extends properties", {
+var AST_Class = DEFNODE("Class", "name extends properties inlined", {
     $propdoc: {
         name: "[AST_SymbolClass|AST_SymbolDefClass?] optional class name.",
         extends: "[AST_Node]? optional parent class",

lib/compress.js

@@ -329,6 +329,7 @@ merge(Compressor.prototype, {
                         value = node.fixed_value();
                         if (value && ref_once(d) && !compressor.exposed(d)) {
                             d.single_use = value instanceof AST_Lambda
+                                || value instanceof AST_Class
                                 || d.scope === node.scope && value.is_constant_expression();
                         } else {
                             d.single_use = false;
@@ -386,7 +387,7 @@ merge(Compressor.prototype, {
                         }
                     }
                 }
-                if (node instanceof AST_Defun) {
+                if (node instanceof AST_DefClass || node instanceof AST_Defun) {
                     node.inlined = false;
                     var d = node.name.definition();
                     if (compressor.exposed(d) || safe_to_read(d)) {
@@ -403,6 +404,13 @@ merge(Compressor.prototype, {
                     safe_ids = save_ids;
                     return true;
                 }
+                if (node instanceof AST_ClassExpression) {
+                    node.inlined = false;
+                    push();
+                    descend();
+                    pop();
+                    return true;
+                }
                 if (is_func_expr(node)) {
                     node.inlined = false;
                     push();
@@ -2385,9 +2393,8 @@ merge(Compressor.prototype, {
                     return false;
             return true;
         }
-        def(AST_Node, return_false);
-        def(AST_Constant, return_true);
-        def(AST_Lambda, function(scope){
+
+        function all_refs_local(scope) {
             var self = this;
             var result = true;
             self.walk(new TreeWalker(function(node) {
@@ -2413,7 +2420,12 @@ merge(Compressor.prototype, {
                 }
             }));
             return result;
-        });
+        }
+
+        def(AST_Node, return_false);
+        def(AST_Constant, return_true);
+        def(AST_Class, all_refs_local);
+        def(AST_Lambda, all_refs_local);
         def(AST_Unary, function(){
             return this.expression.is_constant_expression();
         });
@@ -4599,12 +4611,15 @@ merge(Compressor.prototype, {
             && is_lhs(self, compressor.parent()) !== self) {
             var d = self.definition();
             var fixed = self.fixed_value();
+            if (fixed instanceof AST_DefClass) {
+                d.fixed = fixed = make_node(AST_ClassExpression, fixed, fixed);
+            }
             if (fixed instanceof AST_Defun) {
                 d.fixed = fixed = make_node(AST_Function, fixed, fixed);
             }
-            if (d.single_use && is_func_expr(fixed)) {
+            if (d.single_use && (is_func_expr(fixed) || fixed instanceof AST_ClassExpression)) {
                 if (d.scope !== self.scope
-                    && (!compressor.option("reduce_funcs")
+                    && (!compressor.option("reduce_funcs") && is_func_expr(fixed)
                         || d.escaped
                         || fixed.inlined)) {
                     d.single_use = false;

test/compress/reduce_vars.js

@@ -4849,7 +4849,7 @@ issue_2496: {
         new Foo("FAIL").run();
     }
     expect: {
-        class Foo {
+        new class {
             constructor(message) {
                 this.message = message;
             }
@@ -4864,9 +4864,26 @@ issue_2496: {
                     this.go();
                 });
             }
-        }
-        new Foo("FAIL").run();
+        }("FAIL").run();
     }
     expect_stdout: "PASS"
     node_version: ">=6"
 }
+
+issue_2416: {
+    options = {
+        keep_classnames: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        class Foo {}
+        console.log(Foo.name);
+    }
+    expect: {
+        console.log((class Foo {}).name);
+    }
+    expect_stdout: "Foo"
+    node_version: ">=6"
+}

test/mocha/spidermonkey.js

@@ -10,7 +10,7 @@ describe("spidermonkey export/import sanity test", function() {
         var command = uglifyjs + " --self -cm --wrap SpiderUglify -o spidermonkey | " +
             uglifyjs + " -p spidermonkey -cm";
 
-        exec(command, function(err, stdout) {
+        exec(command, { maxBuffer: 1048576 }, function(err, stdout) {
             if (err) throw err;
 
             eval(stdout);