Use evaluate helper in removeUndefined transform

packages/babel-plugin-transform-remove-undefined/README.md

@@ -57,3 +57,7 @@ require("babel-core").transform("code", {
   plugins: ["babel-plugin-transform-remove-undefined"]
 });
 ```
+
+## Options
+
++ `tdz` - Detect usages before declaration/initialization in let/const(throws) and var(void 0)

packages/babel-plugin-transform-remove-undefined/package.json

@@ -10,5 +10,8 @@
   "license": "MIT",
   "author": "shinew",
   "main": "lib/index.js",
-  "repository": "https://github.com/babel/minify/tree/master/packages/babel-plugin-transform-remove-undefined"
+  "repository": "https://github.com/babel/minify/tree/master/packages/babel-plugin-transform-remove-undefined",
+  "dependencies": {
+    "babel-helper-evaluate-path": "^0.1.0"
+  }
 }

packages/babel-plugin-transform-remove-undefined/src/index.js

@@ -1,6 +1,11 @@
 "use strict";
 
-function isPureAndUndefined(rval, scope = { hasBinding: () => false }) {
+const evaluate = require("babel-helper-evaluate-path");
+
+function isPureAndUndefined(
+  rval,
+  { tdz, scope = { hasBinding: () => false } } = {}
+) {
   if (rval.isIdentifier() && rval.node.name === "undefined") {
     // deopt right away if undefined is a local binding
     if (scope.hasBinding(rval.node.name, true /* no globals */)) {
@@ -12,7 +17,7 @@ function isPureAndUndefined(rval, scope = { hasBinding: () => false }) {
   if (!rval.isPure()) {
     return false;
   }
-  const evaluation = rval.evaluate();
+  const evaluation = evaluate(rval, { tdz });
   return evaluation.confident === true && evaluation.value === undefined;
 }
 
@@ -96,12 +101,12 @@ module.exports = function() {
   return {
     name: "transform-remove-undefined",
     visitor: {
-      SequenceExpression(path) {
+      SequenceExpression(path, { opts: { tdz } = {} }) {
         const expressions = path.get("expressions");
 
         for (let i = 0; i < expressions.length; i++) {
           const expr = expressions[i];
-          if (!isPureAndUndefined(expr, path.scope)) continue;
+          if (!isPureAndUndefined(expr, { tdz, scope: path.scope })) continue;
 
           // last value
           if (i === expressions.length - 1) {
@@ -114,21 +119,26 @@ module.exports = function() {
         }
       },
 
-      ReturnStatement(path) {
+      ReturnStatement(path, { opts: { tdz } = {} }) {
         if (path.node.argument !== null) {
-          if (isPureAndUndefined(path.get("argument"), path.scope)) {
+          if (
+            isPureAndUndefined(path.get("argument"), {
+              tdz,
+              scope: path.scope
+            })
+          ) {
             path.node.argument = null;
           }
         }
       },
 
-      VariableDeclaration(path) {
+      VariableDeclaration(path, { opts: { tdz } = {} }) {
         switch (path.node.kind) {
           case "const":
             break;
           case "let":
             for (const declarator of path.get("declarations")) {
-              if (isPureAndUndefined(declarator.get("init"))) {
+              if (isPureAndUndefined(declarator.get("init"), { tdz })) {
                 declarator.node.init = null;
               }
             }

packages/babel-preset-minify/README.md

@@ -100,7 +100,7 @@ OptionName          | Plugins
 ----------          | -------
 keepFnName          | Passed to [mangle][mangle] & [deadcode][deadcode]
 keepClassName       | Passed to [mangle][mangle] & [deadcode][deadcode]
-tdz                 | Passed to [builtIns][builtIns], [evaluate][evaluate] & [deadcode][deadcode]
+tdz                 | Passed to [builtIns][builtIns], [evaluate][evaluate], [deadcode][deadcode], [removeUndefined][removeUndefined]
 
 **Examples**
 

packages/babel-preset-minify/__tests__/babili-es2015-tests.js

@@ -42,4 +42,26 @@ describe("preset along with es2015", () => {
       key = obj.k, foo();
     `
   );
+
+  thePlugin(
+    "should fix issue#614",
+    `
+      function a() {
+        var c = 1
+        class B {}
+        return B
+      }
+    `,
+    `
+      "use strict";
+
+      function _classCallCheck(a, b) { if (!(a instanceof b)) throw new TypeError("Cannot call a class as a function"); }
+
+      function a() {
+        return function a() {
+          _classCallCheck(this, a);
+        };
+      }
+    `
+  );
 });

packages/babel-preset-minify/src/index.js

@@ -34,7 +34,7 @@ const PLUGINS = [
 const PROXIES = {
   keepFnName: ["mangle", "deadcode"],
   keepClassName: ["mangle", "deadcode"],
-  tdz: ["builtIns", "evaluate", "deadcode"]
+  tdz: ["builtIns", "evaluate", "deadcode", "removeUndefined"]
 };
 
 module.exports = preset;