Mark transpiled JSX elements as pure

packages/babel-generator/src/printer.js

@@ -262,6 +262,8 @@ export default class Printer {
       if (i + 1 === str.length) return;
       const chaPost = str[i + 1];
       if (chaPost !== "/" && chaPost !== "*") return;
+      // We don't print newlines aroung /*#__PURE__*/ annotations
+      if (PURE_ANNOTATION_RE.test(str.slice(i + 2, str.length - 2))) return;
     }
     this.token("(");
     this.indent();

packages/babel-helper-builder-react-jsx-experimental/package.json

@@ -9,6 +9,7 @@
   },
   "main": "lib/index.js",
   "dependencies": {
+    "@babel/helper-annotate-as-pure": "^7.8.3",
     "@babel/helper-module-imports": "^7.8.3",
     "@babel/types": "^7.8.3",
     "esutils": "^2.0.0"

packages/babel-helper-builder-react-jsx-experimental/src/index.js

@@ -1,6 +1,14 @@
 import esutils from "esutils";
 import * as t from "@babel/types";
 import { addNamed, addNamespace, isModule } from "@babel/helper-module-imports";
+import annotateAsPure from "@babel/helper-annotate-as-pure";
+
+const DEFAULT = {
+  importSource: "react",
+  runtime: "automatic",
+  pragma: "React.createElement",
+  pragmaFrag: "React.Fragment",
+};
 
 export function helper(babel, options) {
   const FILE_NAME_VAR = "_jsxFileName";
@@ -17,10 +25,10 @@ export function helper(babel, options) {
   const IMPORT_NAME_SIZE = options.development ? 3 : 4;
 
   const {
-    importSource: IMPORT_SOURCE_DEFAULT = "react",
-    runtime: RUNTIME_DEFAULT = "automatic",
-    pragma: PRAGMA_DEFAULT = "React.createElement",
-    pragmaFrag: PRAGMA_FRAG_DEFAULT = "React.Fragment",
+    importSource: IMPORT_SOURCE_DEFAULT = DEFAULT.importSource,
+    runtime: RUNTIME_DEFAULT = DEFAULT.runtime,
+    pragma: PRAGMA_DEFAULT = DEFAULT.pragma,
+    pragmaFrag: PRAGMA_FRAG_DEFAULT = DEFAULT.pragmaFrag,
   } = options;
 
   return {
@@ -142,8 +150,14 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
               createIdentifierParser(pragmaFrag),
             );
             state.set("@babel/plugin-react-jsx/usedFragment", false);
-            state.set("@babel/plugin-react-jsx/pragmaSet", pragmaSet);
-            state.set("@babel/plugin-react-jsx/pragmaFragSet", pragmaFragSet);
+            state.set(
+              "@babel/plugin-react-jsx/pragmaSet",
+              pragma !== DEFAULT.pragma,
+            );
+            state.set(
+              "@babel/plugin-react-jsx/pragmaFragSet",
+              pragmaFrag !== DEFAULT.pragmaFrag,
+            );
           } else if (runtime === "automatic") {
             if (pragmaSet || pragmaFragSet) {
               throw path.buildCodeFrameError(
@@ -190,6 +204,11 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
                 createIdentifierName(path, "Fragment", importName),
               ),
             );
+
+            state.set(
+              "@babel/plugin-react-jsx/importSourceSet",
+              source !== DEFAULT.importSource,
+            );
           } else {
             throw path.buildCodeFrameError(
               `Runtime must be either "classic" or "automatic".`,
@@ -505,6 +524,7 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
       tagExpr: tagExpr,
       tagName: tagName,
       args: args,
+      pure: false,
     };
 
     if (options.pre) {
@@ -577,13 +597,15 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
       options.post(state, file);
     }
 
-    return (
+    const call =
       state.call ||
       t.callExpression(
         path.node.children.length > 1 ? state.jsxStaticCallee : state.jsxCallee,
         args,
-      )
-    );
+      );
+    if (state.pure) annotateAsPure(call);
+
+    return call;
   }
 
   // Builds props for React.jsx. This function adds children into the props
@@ -633,6 +655,7 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
       tagExpr: tagExpr,
       tagName: tagName,
       args: args,
+      pure: false,
     };
 
     if (options.pre) {
@@ -667,13 +690,15 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
       options.post(state, file);
     }
 
-    return (
+    const call =
       state.call ||
       t.callExpression(
         path.node.children.length > 1 ? state.jsxStaticCallee : state.jsxCallee,
         args,
-      )
-    );
+      );
+    if (state.pure) annotateAsPure(call);
+
+    return call;
   }
 
   function buildCreateElementFragmentCall(path, file) {
@@ -692,6 +717,7 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
       tagExpr: tagExpr,
       tagName: tagName,
       args: args,
+      pure: false,
     };
 
     if (options.pre) {
@@ -706,7 +732,12 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
     }
 
     file.set("@babel/plugin-react-jsx/usedFragment", true);
-    return state.call || t.callExpression(state.createElementCallee, args);
+
+    const call =
+      state.call || t.callExpression(state.createElementCallee, args);
+    if (state.pure) annotateAsPure(call);
+
+    return call;
   }
 
   // Builds JSX into:
@@ -733,6 +764,7 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
       tagExpr: tagExpr,
       tagName: tagName,
       args: args,
+      pure: false,
     };
 
     if (options.pre) {
@@ -751,7 +783,11 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
       options.post(state, file);
     }
 
-    return state.call || t.callExpression(state.createElementCallee, args);
+    const call =
+      state.call || t.callExpression(state.createElementCallee, args);
+    if (state.pure) annotateAsPure(call);
+
+    return call;
   }
 
   /**

packages/babel-helper-builder-react-jsx/package.json

@@ -9,6 +9,7 @@
   },
   "main": "lib/index.js",
   "dependencies": {
+    "@babel/helper-annotate-as-pure": "^7.8.3",
     "@babel/types": "^7.8.3",
     "esutils": "^2.0.0"
   }

packages/babel-helper-builder-react-jsx/src/index.js

@@ -1,11 +1,13 @@
 import esutils from "esutils";
 import * as t from "@babel/types";
+import annotateAsPure from "@babel/helper-annotate-as-pure";
 
 type ElementState = {
   tagExpr: Object, // tag node
   tagName: ?string, // raw string tag name
   args: Array<Object>, // array of call arguments
   call?: Object, // optional call property that can be set to override the call expression returned
+  pure: boolean, // true if the element can be marked with a #__PURE__ annotation
 };
 
 export default function(opts) {
@@ -134,6 +136,7 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
       tagExpr: tagExpr,
       tagName: tagName,
       args: args,
+      pure: false,
     };
 
     if (opts.pre) {
@@ -153,7 +156,10 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
       opts.post(state, file);
     }
 
-    return state.call || t.callExpression(state.callee, args);
+    const call = state.call || t.callExpression(state.callee, args);
+    if (state.pure) annotateAsPure(call);
+
+    return call;
   }
 
   function pushProps(_props, objs) {
@@ -248,6 +254,7 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
       tagExpr: tagExpr,
       tagName: tagName,
       args: args,
+      pure: false,
     };
 
     if (opts.pre) {
@@ -262,6 +269,10 @@ You can set \`throwIfNamespace: false\` to bypass this warning.`,
     }
 
     file.set("usedFragment", true);
-    return state.call || t.callExpression(state.callee, args);
+
+    const call = state.call || t.callExpression(state.callee, args);
+    if (state.pure) annotateAsPure(call);
+
+    return call;
   }
 }

packages/babel-plugin-transform-block-scoping/test/fixtures/general/jsx-identifier/output.js

@@ -2,5 +2,5 @@
 var arr = [];
 
 for (var i = 0; i < 4; ++i) {
-  arr.push(React.createElement("i", null));
+  arr.push( /*#__PURE__*/React.createElement("i", null));
 }

packages/babel-plugin-transform-classes/test/fixtures/regression/2775/output.js

@@ -24,9 +24,9 @@ var RandomComponent = /*#__PURE__*/function (_Component) {
   babelHelpers.createClass(RandomComponent, [{
     key: "render",
     value: function render() {
-      return _react["default"].createElement("div", {
+      return /*#__PURE__*/_react["default"].createElement("div", {
         className: "sui-RandomComponent"
-      }, _react["default"].createElement("h2", null, "Hi there!"));
+      }, /*#__PURE__*/_react["default"].createElement("h2", null, "Hi there!"));
     }
   }]);
   return RandomComponent;

packages/babel-plugin-transform-classes/test/fixtures/regression/T6750/output.js

@@ -6,16 +6,15 @@ Object.defineProperty(exports, "__esModule", {
 exports["default"] = _default;
 
 function _default() {
-  return (/*#__PURE__*/function () {
-      function Select() {
-        babelHelpers.classCallCheck(this, Select);
-      }
+  return /*#__PURE__*/function () {
+    function Select() {
+      babelHelpers.classCallCheck(this, Select);
+    }
 
-      babelHelpers.createClass(Select, [{
-        key: "query",
-        value: function query(_query) {}
-      }]);
-      return Select;
-    }()
-  );
+    babelHelpers.createClass(Select, [{
+      key: "query",
+      value: function query(_query) {}
+    }]);
+    return Select;
+  }();
 }

packages/babel-plugin-transform-function-name/test/fixtures/function-name/export-default-arrow-renaming-3/output.js

@@ -7,7 +7,7 @@ exports["default"] = void 0;
 
 var _default = function _default(_ref) {
   var _onClick = _ref.onClick;
-  return React.createElement("div", {
+  return /*#__PURE__*/React.createElement("div", {
     onClick: function onClick() {
       return _onClick();
     }

packages/babel-plugin-transform-react-constant-elements/package.json

@@ -12,7 +12,6 @@
     "babel-plugin"
   ],
   "dependencies": {
-    "@babel/helper-annotate-as-pure": "^7.8.3",
     "@babel/helper-plugin-utils": "^7.8.3"
   },
   "peerDependencies": {

packages/babel-plugin-transform-react-constant-elements/src/index.js

@@ -1,6 +1,5 @@
 import { declare } from "@babel/helper-plugin-utils";
 import { types as t } from "@babel/core";
-import annotateAsPure from "@babel/helper-annotate-as-pure";
 
 export default declare((api, options) => {
   api.assertVersion(7);
@@ -107,13 +106,7 @@ export default declare((api, options) => {
         // Traverse all props passed to this element for immutability.
         path.traverse(immutabilityVisitor, state);
 
-        if (state.isImmutable) {
-          const hoisted = path.hoist();
-
-          if (hoisted) {
-            annotateAsPure(hoisted);
-          }
-        }
+        if (state.isImmutable) path.hoist();
       },
     },
   };

packages/babel-plugin-transform-react-constant-elements/test/fixtures/constant-elements/append-to-end-when-declared-in-scope-2/output.mjs

@@ -1,10 +1,10 @@
-var _ref = /*#__PURE__*/<div>child</div>;
+var _ref = <div>child</div>;
 
 const AppItem = () => {
   return _ref;
 };
 
-var _ref2 = /*#__PURE__*/<div>
+var _ref2 = <div>
         <p>Parent</p>
         <AppItem />
       </div>;

packages/babel-plugin-transform-react-constant-elements/test/fixtures/constant-elements/append-to-end-when-declared-in-scope-3/output.js

@@ -1,6 +1,6 @@
-var _ref2 = /*#__PURE__*/<div>child</div>;
+var _ref2 = <div>child</div>;
 
-var _ref3 = /*#__PURE__*/<p>Parent</p>;
+var _ref3 = <p>Parent</p>;
 
 (function () {
   class App extends React.Component {
@@ -13,7 +13,7 @@ var _ref3 = /*#__PURE__*/<p>Parent</p>;
   const AppItem = () => {
     return _ref2;
   },
-        _ref = /*#__PURE__*/<div>
+        _ref = <div>
           {_ref3}
           <AppItem />
         </div>;

packages/babel-plugin-transform-react-constant-elements/test/fixtures/constant-elements/append-to-end-when-declared-in-scope-4/output.js

@@ -1,13 +1,13 @@
-var _ref = /*#__PURE__*/<div>child</div>;
+var _ref = <div>child</div>;
 
-var _ref3 = /*#__PURE__*/<p>Parent</p>;
+var _ref3 = <p>Parent</p>;
 
 (function () {
   const AppItem = () => {
     return _ref;
   };
 
-  var _ref2 = /*#__PURE__*/<div>
+  var _ref2 = <div>
           {_ref3}
           <AppItem />
         </div>;

packages/babel-plugin-transform-react-constant-elements/test/fixtures/constant-elements/append-to-end-when-declared-in-scope/output.mjs

@@ -5,12 +5,12 @@ export default class App extends React.Component {
 
 }
 
-var _ref2 = /*#__PURE__*/<div>child</div>;
+var _ref2 = <div>child</div>;
 
 const AppItem = () => {
   return _ref2;
 },
-      _ref = /*#__PURE__*/<div>
+      _ref = <div>
         <p>Parent</p>
         <AppItem />
       </div>;

packages/babel-plugin-transform-react-constant-elements/test/fixtures/constant-elements/children/output.js

@@ -1,4 +1,4 @@
-var _ref = /*#__PURE__*/<span />;
+var _ref = <span />;
 
 var Foo = React.createClass({
   render: function () {

packages/babel-plugin-transform-react-constant-elements/test/fixtures/constant-elements/class-assign-unreferenced-param-deopt/output.mjs

@@ -1,6 +1,6 @@
 import React from 'react'; // Regression test for https://github.com/babel/babel/issues/5552
 
-var _ref = /*#__PURE__*/<div />;
+var _ref = <div />;
 
 class BugReport extends React.Component {
   constructor(...args) {