Make tdz optional in helper evaluate

packages/babel-helper-evaluate-path/src/index.js

@@ -1,6 +1,10 @@
 "use strict";
 
-module.exports = function evaluate(path) {
+module.exports = function evaluate(path, { tdz = false } = {}) {
+  if (!tdz) {
+    return baseEvaluate(path);
+  }
+
   if (path.isReferencedIdentifier()) {
     return evaluateIdentifier(path);
   }
@@ -32,6 +36,10 @@ module.exports = function evaluate(path) {
     return state;
   }
 
+  return baseEvaluate(path);
+};
+
+function baseEvaluate(path) {
   try {
     return path.evaluate();
   } catch (e) {
@@ -40,7 +48,7 @@ module.exports = function evaluate(path) {
       error: e
     };
   }
-};
+}
 
 // Original Source:
 // https://github.com/babel/babel/blob/master/packages/babel-traverse/src/path/evaluation.js

packages/babel-minify/src/cli.js

@@ -28,7 +28,7 @@ const plugins = [
   "undefinedToVoid"
 ];
 
-const proxies = ["keepFnName", "keepClassName"];
+const proxies = ["keepFnName", "keepClassName", "tdz"];
 
 const dceBooleanOpts = [
   "deadcode.keepFnName",
@@ -72,9 +72,11 @@ function printHelpInfo({ exitCode = 0 } = {}) {
   const msg = `
   Usage: minify index.js [options]
 
-  Options:
+  IO Options:
     --out-file, -o          Output to a specific file
     --out-dir, -d           Output to a specific directory
+
+  Transform Options:
     --mangle                Context and scope aware variable renaming
     --simplify              Simplifies code for minification by reducing statements into
                             expressions
@@ -102,7 +104,12 @@ function printHelpInfo({ exitCode = 0 } = {}) {
                             to be the same
     --typeConstructors      Minify constructors to equivalent version
     --undefinedToVoid       Transforms undefined into void 0
-    --version, -V           Prints the current version number
+
+  Other Options:
+    --keepFnName            Preserve Function Name (useful for code depending on fn.name)
+    --keepClassName         Preserve Class Name (useful for code depending on c.name)
+    --keepFnArgs            Don't remove unused fn arguments (useful for code depending on fn.length)
+    --tdz                   Detect usages of variables in the Temporal Dead Zone
 
   Nested Options:
     To use nested options (plugin specfic options) simply use the pattern

packages/babel-plugin-minify-builtins/README.md

@@ -49,3 +49,7 @@ require("babel-core").transform("code", {
   plugins: ["minify-builtins"]
 });
 ```
+
+## Options
+
++ `tdz` - Account for TDZ (Temporal Dead Zone)

packages/babel-plugin-minify-builtins/src/index.js

@@ -8,8 +8,9 @@ const INVALID_METHODS = ["random"];
 
 module.exports = function({ types: t }) {
   class BuiltInReplacer {
-    constructor(program) {
+    constructor(program, { tdz }) {
       this.program = program;
+      this.tdz = tdz;
       // map<expr_name, path[]>;
       this.pathsToUpdate = new Map();
     }
@@ -48,7 +49,7 @@ module.exports = function({ types: t }) {
             // computed property should be not optimized
             // Math[max]() -> Math.max()
             if (!isComputed(callee) && isBuiltin(callee)) {
-              const result = evaluate(path);
+              const result = evaluate(path, { tdz: context.tdz });
               // deopt when we have side effecty evaluate-able arguments
               // Math.max(foo(), 1) --> untouched
               // Math.floor(1) --> 1
@@ -96,8 +97,8 @@ module.exports = function({ types: t }) {
   return {
     name: "minify-builtins",
     visitor: {
-      Program(path) {
-        const builtInReplacer = new BuiltInReplacer(path);
+      Program(path, { opts: { tdz = false } = {} }) {
+        const builtInReplacer = new BuiltInReplacer(path, { tdz });
         builtInReplacer.run();
       }
     }

packages/babel-plugin-minify-constant-folding/README.md

@@ -84,3 +84,7 @@ require("babel-core").transform("code", {
   plugins: ["minify-constant-folding"]
 });
 ```
+
+## Options
+
++ `tdz` - Account for TDZ (Temporal Dead Zone)

packages/babel-plugin-minify-constant-folding/src/index.js

@@ -95,7 +95,7 @@ module.exports = babel => {
       },
 
       // TODO: look into evaluating binding too (could result in more code, but gzip?)
-      Expression(path) {
+      Expression(path, { opts: { tdz = false } = {} }) {
         const { node } = path;
 
         if (node[seen]) {
@@ -143,7 +143,7 @@ module.exports = babel => {
           return;
         }
 
-        const res = evaluate(path);
+        const res = evaluate(path, { tdz });
         if (res.confident) {
           // Avoid fractions because they can be longer than the original expression.
           // There is also issues with number percision?

packages/babel-plugin-minify-dead-code-elimination/README.md

@@ -70,4 +70,5 @@ require("babel-core").transform("code", {
 
 + `keepFnName` - prevent plugin from removing function name. Useful for code depending on `fn.name`
 + `keepFnArgs` - prevent plugin from removing function args. Useful for code depending on `fn.length`
-+ `keepClassName` - prevent mangler from altering class names.
++ `keepClassName` - prevent plugin from removing class name. Useful for code depending on `cls.name`
++ `tdz` - Account for TDZ (Temporal Dead Zone)

packages/babel-plugin-minify-dead-code-elimination/__tests__/dead-code-elimination-test.js

@@ -525,7 +525,10 @@ describe("dce-plugin", () => {
         if (a) return;
         x();
       }
-    `
+    `,
+    {
+      plugins: [[deadcode, { tdz: true }]]
+    }
   );
 
   thePlugin(
@@ -536,7 +539,10 @@ describe("dce-plugin", () => {
         if (a) return 1;
         x();
       }
-    `
+    `,
+    {
+      plugins: [[deadcode, { tdz: true }]]
+    }
   );
 
   thePlugin(
@@ -552,7 +558,10 @@ describe("dce-plugin", () => {
           y();
         }
       }
-    `
+    `,
+    {
+      plugins: [[deadcode, { tdz: true }]]
+    }
   );
 
   thePlugin(
@@ -2452,7 +2461,10 @@ describe("dce-plugin", () => {
         if (v) var w = 10;
         if (w) console.log("hello", v);
       }
-    `
+    `,
+    {
+      plugins: [[deadcode, { tdz: true }]]
+    }
   );
 
   thePlugin.skip(
@@ -2462,7 +2474,10 @@ describe("dce-plugin", () => {
         bar(a); // Should be a ReferenceError
         let a = 1;
       }
-    `
+    `,
+    {
+      plugins: [[deadcode, { tdz: true }]]
+    }
   );
 
   thePlugin(
@@ -2483,6 +2498,9 @@ describe("dce-plugin", () => {
           if (a) console.log(a);
         };
       }
-    `
+    `,
+    {
+      plugins: [[deadcode, { tdz: true }]]
+    }
   );
 });

packages/babel-plugin-minify-dead-code-elimination/src/index.js

@@ -509,7 +509,7 @@ module.exports = ({ types: t, traverse }) => {
 
     SwitchStatement: {
       exit(path) {
-        const evaluated = evaluate(path.get("discriminant"));
+        const evaluated = evaluate(path.get("discriminant"), { tdz: this.tdz });
 
         if (!evaluated.confident) return;
 
@@ -528,7 +528,7 @@ module.exports = ({ types: t, traverse }) => {
             continue;
           }
 
-          const testResult = evaluate(test);
+          const testResult = evaluate(test, { tdz: this.tdz });
 
           // if we are not able to deternine a test during
           // compile time, we terminate immediately
@@ -614,7 +614,7 @@ module.exports = ({ types: t, traverse }) => {
 
     WhileStatement(path) {
       const test = path.get("test");
-      const result = evaluate(test);
+      const result = evaluate(test, { tdz: this.tdz });
       if (result.confident && test.isPure() && !result.value) {
         path.remove();
       }
@@ -624,7 +624,7 @@ module.exports = ({ types: t, traverse }) => {
       const test = path.get("test");
       if (!test.isPure()) return;
 
-      const result = evaluate(test);
+      const result = evaluate(test, { tdz: this.tdz });
       if (result.confident) {
         if (result.value) {
           test.remove();
@@ -636,7 +636,7 @@ module.exports = ({ types: t, traverse }) => {
 
     DoWhileStatement(path) {
       const test = path.get("test");
-      const result = evaluate(test);
+      const result = evaluate(test, { tdz: this.tdz });
       if (result.confident && test.isPure() && !result.value) {
         const body = path.get("body");
 
@@ -767,12 +767,12 @@ module.exports = ({ types: t, traverse }) => {
         }
       },
       IfStatement: {
-        exit(path) {
+        exit(path, { opts: { tdz = false } = {} }) {
           const consequent = path.get("consequent");
           const alternate = path.get("alternate");
           const test = path.get("test");
 
-          const evalResult = evaluate(test);
+          const evalResult = evaluate(test, { tdz });
           const isPure = test.isPure();
 
           const replacements = [];
@@ -864,7 +864,8 @@ module.exports = ({ types: t, traverse }) => {
               optimizeRawSize = false,
               keepFnName = false,
               keepClassName = false,
-              keepFnArgs = false
+              keepFnArgs = false,
+              tdz = false
             } = {}
           } = {}
         ) {
@@ -879,7 +880,8 @@ module.exports = ({ types: t, traverse }) => {
             optimizeRawSize,
             keepFnName,
             keepClassName,
-            keepFnArgs
+            keepFnArgs,
+            tdz
           });
         }
       }

packages/babel-preset-minify/README.md

@@ -100,6 +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]
 
 **Examples**
 

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

@@ -33,7 +33,8 @@ const PLUGINS = [
 
 const PROXIES = {
   keepFnName: ["mangle", "deadcode"],
-  keepClassName: ["mangle", "deadcode"]
+  keepClassName: ["mangle", "deadcode"],
+  tdz: ["builtIns", "evaluate", "deadcode"]
 };
 
 module.exports = preset;