Add optionality to catch bindings (#5956)

packages/babel-core/package.json

@@ -32,7 +32,7 @@
     "babel-template": "7.0.0-alpha.15",
     "babel-traverse": "7.0.0-alpha.15",
     "babel-types": "7.0.0-alpha.15",
-    "babylon": "7.0.0-beta.15",
+    "babylon": "7.0.0-beta.17",
     "convert-source-map": "^1.1.0",
     "debug": "^2.1.1",
     "json5": "^0.5.0",

packages/babel-generator/package.json

@@ -20,6 +20,6 @@
   },
   "devDependencies": {
     "babel-helper-fixtures": "7.0.0-alpha.15",
-    "babylon": "^7.0.0-beta.15"
+    "babylon": "^7.0.0-beta.17"
   }
 }

packages/babel-generator/src/generators/statements.js

@@ -171,10 +171,12 @@ export function TryStatement(node: Object) {
 export function CatchClause(node: Object) {
   this.word("catch");
   this.space();
-  this.token("(");
+  if (node.param) {
-  this.print(node.param, node);
+    this.token("(");
-  this.token(")");
+    this.print(node.param, node);
-  this.space();
+    this.token(")");
+    this.space();
+  }
   this.print(node.body, node);
 }
 

packages/babel-generator/test/fixtures/types/Optional-TryStatement-CatchClause/actual.js

@@ -0,0 +1,51 @@
+try {} catch (err) {}
+
+try {} catch {}
+
+try {
+  bar;
+} catch (err) {}
+
+try {
+  bar;
+} catch {}
+
+try {
+  bar;
+} catch (err) {
+  foo();
+}
+
+try {
+  bar;
+} catch {
+  foo();
+}
+
+try {
+  bar;
+} catch (err) {
+  foo();
+} finally {
+  yay();
+}
+
+try {
+  bar;
+} catch {
+  foo();
+} finally {
+  yay();
+}
+
+try {
+  bar;
+} catch (err) {
+  foo();
+} finally {}
+
+try {
+  bar;
+} catch {
+  foo();
+} finally {}

packages/babel-generator/test/fixtures/types/Optional-TryStatement-CatchClause/expected.js

@@ -0,0 +1,51 @@
+try {} catch (err) {}
+
+try {} catch {}
+
+try {
+  bar;
+} catch (err) {}
+
+try {
+  bar;
+} catch {}
+
+try {
+  bar;
+} catch (err) {
+  foo();
+}
+
+try {
+  bar;
+} catch {
+  foo();
+}
+
+try {
+  bar;
+} catch (err) {
+  foo();
+} finally {
+  yay();
+}
+
+try {
+  bar;
+} catch {
+  foo();
+} finally {
+  yay();
+}
+
+try {
+  bar;
+} catch (err) {
+  foo();
+} finally {}
+
+try {
+  bar;
+} catch {
+  foo();
+} finally {}

packages/babel-generator/test/index.js

@@ -388,6 +388,7 @@ suites.forEach(function(testSuite) {
                   "jsx",
                   "objectRestSpread",
                   "optionalChaining",
+                  "optionalCatchBinding",
                 ],
                 strictMode: false,
                 sourceType: "module",

packages/babel-plugin-syntax-optional-catch-binding/.npmignore

@@ -0,0 +1,3 @@
+src
+test
+*.log

packages/babel-plugin-syntax-optional-catch-binding/README.md

@@ -0,0 +1,52 @@
+# babel-plugin-syntax-optional-catch-binding
+
+> This plugin allows Babel to parse optional catch bindings.
+
+## Example
+
+**Syntax**
+
+```javascript
+try {
+  throw 0;
+} catch {
+  doSomethingWhichDoesntCareAboutTheValueThrown();
+  console.log("Yay, code executes!");
+}
+```
+
+## Installation
+
+```sh
+npm install --save-dev babel-plugin-syntax-optional-catch-binding
+```
+
+## Usage
+
+### Via `.babelrc` (Recommended)
+
+**.babelrc**
+
+```json
+{
+  "plugins": ["syntax-optional-catch-binding"]
+}
+```
+
+### Via CLI
+
+```sh
+babel --plugins syntax-optional-catch-binding script.js
+```
+
+### Via Node API
+
+```javascript
+require("babel-core").transform("code", {
+  plugins: ["syntax-optional-catch-binding"]
+});
+```
+
+## References
+
+* [Proposal: Optional Catch Binding for ECMAScript](https://github.com/babel/proposals/issues/7)

packages/babel-plugin-syntax-optional-catch-binding/package.json

@@ -0,0 +1,13 @@
+{
+  "name": "babel-plugin-syntax-optional-catch-binding",
+  "version": "7.0.0-alpha.15",
+  "description": "Allow parsing of optional catch bindings",
+  "repository": "https://github.com/babel/babel/tree/master/packages/babel-plugin-syntax-optional-catch-binding",
+  "license": "MIT",
+  "main": "lib/index.js",
+  "keywords": [
+    "babel-plugin"
+  ],
+  "dependencies": {},
+  "devDependencies": {}
+}

packages/babel-plugin-syntax-optional-catch-binding/src/index.js

@@ -0,0 +1,7 @@
+export default function() {
+  return {
+    manipulateOptions(opts, parserOpts) {
+      parserOpts.plugins.push("optionalCatchBinding");
+    },
+  };
+}

packages/babel-plugin-transform-optional-catch-binding/.npmignore

@@ -0,0 +1,3 @@
+src
+test
+*.log

packages/babel-plugin-transform-optional-catch-binding/README.md

@@ -0,0 +1,60 @@
+# babel-plugin-transform-optional-catch-binding
+
+> Optional catch binding enables the catch block to execute whether or not an argument is passed to the catch statement (CatchClause).
+
+
+## Examples
+
+```js
+try {
+  throw 0;
+} catch {
+  doSomethingWhichDoesntCareAboutTheValueThrown();
+}
+```
+
+```js
+try {
+  throw 0;
+} catch {
+  doSomethingWhichDoesntCareAboutTheValueThrown();
+} finally {
+  doSomeCleanup();
+}
+```
+
+
+## Installation
+
+```sh
+npm install --save-dev babel-plugin-transform-optional-catch-binding
+```
+
+## Usage
+
+### Via `.babelrc` (Recommended)
+
+**.babelrc**
+
+```json
+{
+  "plugins": ["transform-optional-catch-binding"]
+}
+```
+
+### Via CLI
+
+```sh
+babel --plugins transform-optional-catch-binding script.js
+```
+
+### Via Node API
+
+```javascript
+require("babel-core").transform("code", {
+  plugins: ["transform-optional-catch-binding"]
+});
+```
+
+## References
+- [Proposal: Optional Catch Binding for ECMAScript](https://github.com/babel/proposals/issues/7)

packages/babel-plugin-transform-optional-catch-binding/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "babel-plugin-transform-optional-catch-binding",
+  "version": "7.0.0-alpha.15",
+  "description": "Compile optional catch bindings",
+  "repository": "https://github.com/babel/babel/tree/master/packages/babel-plugin-transform-optional-catch-binding",
+  "license": "MIT",
+  "main": "lib/index.js",
+  "keywords": [
+    "babel-plugin"
+  ],
+  "dependencies": {
+    "babel-plugin-syntax-optional-catch-binding": "7.0.0-alpha.15"
+  },
+  "devDependencies": {
+    "babel-helper-plugin-test-runner": "7.0.0-alpha.15"
+  }
+}

packages/babel-plugin-transform-optional-catch-binding/src/index.js

@@ -0,0 +1,17 @@
+import syntaxOptionalCatchBinding from "babel-plugin-syntax-optional-catch-binding";
+
+export default function() {
+  return {
+    inherits: syntaxOptionalCatchBinding,
+
+    visitor: {
+      CatchClause(path) {
+        if (!path.node.param) {
+          const uid = path.scope.generateUidIdentifier("unused");
+          const paramPath = path.get("param");
+          paramPath.replaceWith(uid);
+        }
+      },
+    },
+  };
+}

packages/babel-plugin-transform-optional-catch-binding/test/fixtures/optional-catch-bindings/exec.js

@@ -0,0 +1,19 @@
+const test = () => {
+  try {
+    throw 0;
+  }
+  catch {
+    return true;
+  }
+}
+assert(test());
+
+const test2 = () => {
+  try {
+    throw 0;
+  }
+  catch (err) {
+    return true;
+  }
+}
+assert(test2());

packages/babel-plugin-transform-optional-catch-binding/test/fixtures/optional-catch-bindings/try-catch-block-binding/actual.js

@@ -0,0 +1,5 @@
+try {
+  throw 0;
+} catch (err) {
+  console.log("it failed, but this code executes");
+}

packages/babel-plugin-transform-optional-catch-binding/test/fixtures/optional-catch-bindings/try-catch-block-binding/expected.js

@@ -0,0 +1,5 @@
+try {
+  throw 0;
+} catch (err) {
+  console.log("it failed, but this code executes");
+}

packages/babel-plugin-transform-optional-catch-binding/test/fixtures/optional-catch-bindings/try-catch-block-no-binding/actual.js

@@ -0,0 +1,5 @@
+try {
+  throw 0;
+} catch {
+  console.log("it failed, but this code executes");
+}

packages/babel-plugin-transform-optional-catch-binding/test/fixtures/optional-catch-bindings/try-catch-block-no-binding/expected.js

@@ -0,0 +1,5 @@
+try {
+  throw 0;
+} catch (_unused) {
+  console.log("it failed, but this code executes");
+}

packages/babel-plugin-transform-optional-catch-binding/test/fixtures/optional-catch-bindings/try-catch-finally-binding/actual.js

@@ -0,0 +1,7 @@
+try {
+  throw 0;
+} catch (err) {
+  console.log("it failed, but this code executes");
+} finally {
+  console.log("this code also executes");
+}

packages/babel-plugin-transform-optional-catch-binding/test/fixtures/optional-catch-bindings/try-catch-finally-binding/expected.js

@@ -0,0 +1,7 @@
+try {
+  throw 0;
+} catch (err) {
+  console.log("it failed, but this code executes");
+} finally {
+  console.log("this code also executes");
+}

packages/babel-plugin-transform-optional-catch-binding/test/fixtures/optional-catch-bindings/try-catch-finally-no-binding/actual.js

@@ -0,0 +1,7 @@
+try {
+  throw 0;
+} catch {
+  console.log("it failed, but this code executes");
+} finally {
+  console.log("this code also executes");
+}

packages/babel-plugin-transform-optional-catch-binding/test/fixtures/optional-catch-bindings/try-catch-finally-no-binding/expected.js

@@ -0,0 +1,7 @@
+try {
+  throw 0;
+} catch (_unused) {
+  console.log("it failed, but this code executes");
+} finally {
+  console.log("this code also executes");
+}

packages/babel-plugin-transform-optional-catch-binding/test/fixtures/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["transform-optional-catch-binding"]
+}

packages/babel-plugin-transform-optional-catch-binding/test/index.js

@@ -0,0 +1,3 @@
+import runner from "babel-helper-plugin-test-runner";
+
+runner(__dirname);

packages/babel-template/package.json

@@ -10,7 +10,7 @@
   "dependencies": {
     "babel-traverse": "7.0.0-alpha.15",
     "babel-types": "7.0.0-alpha.15",
-    "babylon": "7.0.0-beta.13",
+    "babylon": "7.0.0-beta.17",
     "lodash": "^4.2.0"
   }
 }

packages/babel-traverse/package.json

@@ -12,7 +12,7 @@
     "babel-helper-function-name": "7.0.0-alpha.15",
     "babel-messages": "7.0.0-alpha.15",
     "babel-types": "7.0.0-alpha.15",
-    "babylon": "7.0.0-beta.15",
+    "babylon": "7.0.0-beta.17",
     "debug": "^2.2.0",
     "globals": "^10.0.0",
     "invariant": "^2.2.0",

packages/babel-types/package.json

@@ -14,6 +14,6 @@
   },
   "devDependencies": {
     "babel-generator": "7.0.0-alpha.15",
-    "babylon": "^7.0.0-beta.15"
+    "babylon": "^7.0.0-beta.17"
   }
 }

packages/babel-types/src/definitions/core.js

@@ -143,6 +143,7 @@ defineType("CatchClause", {
   fields: {
     param: {
       validate: assertNodeType("Identifier"),
+      optional: true,
     },
     body: {
       validate: assertNodeType("BlockStatement"),