Add transform support for optional chaining assignment

packages/babel-helpers/src/helpers.ts

@@ -1884,3 +1884,9 @@ helpers.identity = helper("7.17.0")`
     return x;
   }
 `;
+
+helpers.nullishReceiverError = helper("7.22.6")`
+  export default function _nullishReceiverError(r) {
+    throw new TypeError("Cannot set property of null or undefined.");
+  }
+`;

packages/babel-plugin-proposal-optional-chaining-assign/.npmignore

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

packages/babel-plugin-proposal-optional-chaining-assign/README.md

@@ -0,0 +1,19 @@
+# @babel/plugin-transform-optional-chaining
+
+> Transform optional chaining operators into a series of nil checks
+
+See our website [@babel/plugin-transform-optional-chaining](https://babeljs.io/docs/babel-plugin-transform-optional-chaining) for more information.
+
+## Install
+
+Using npm:
+
+```sh
+npm install --save-dev @babel/plugin-transform-optional-chaining
+```
+
+or using yarn:
+
+```sh
+yarn add @babel/plugin-transform-optional-chaining --dev
+```

packages/babel-plugin-proposal-optional-chaining-assign/package.json

@@ -0,0 +1,55 @@
+{
+  "name": "@babel/plugin-proposal-optional-chaining-assign",
+  "version": "7.22.5",
+  "description": "Transform optional chaining on the left-hand side of assignment expressions",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/babel/babel.git",
+    "directory": "packages/babel-plugin-proposal-optional-chaining-assign"
+  },
+  "homepage": "https://babel.dev/docs/en/next/babel-plugin-proposal-optional-chaining-assign",
+  "license": "MIT",
+  "publishConfig": {
+    "access": "public"
+  },
+  "main": "./lib/index.js",
+  "keywords": [
+    "babel-plugin"
+  ],
+  "dependencies": {
+    "@babel/helper-plugin-utils": "workspace:^",
+    "@babel/helper-skip-transparent-expression-wrappers": "workspace:^",
+    "@babel/plugin-syntax-optional-chaining-assign": "workspace:^",
+    "@babel/plugin-transform-optional-chaining": "workspace:^"
+  },
+  "peerDependencies": {
+    "@babel/core": "^7.22.5"
+  },
+  "devDependencies": {
+    "@babel/helper-plugin-test-runner": "workspace:^"
+  },
+  "engines": {
+    "node": ">=6.9.0"
+  },
+  "author": "The Babel Team (https://babel.dev/team)",
+  "conditions": {
+    "BABEL_8_BREAKING": [
+      {
+        "engines": {
+          "node": "^16.20.0 || ^18.16.0 || >=20.0.0"
+        }
+      }
+    ],
+    "USE_ESM": [
+      {
+        "type": "module"
+      },
+      null
+    ]
+  },
+  "exports": {
+    ".": "./lib/index.js",
+    "./package.json": "./package.json"
+  },
+  "type": "commonjs"
+}

packages/babel-plugin-proposal-optional-chaining-assign/src/index.ts

@@ -0,0 +1,53 @@
+import { declare } from "@babel/helper-plugin-utils";
+import syntaxOptionalChainingAssign from "@babel/plugin-syntax-optional-chaining-assign";
+import type { NodePath } from "@babel/traverse";
+import type * as t from "@babel/types";
+import { skipTransparentExprWrappers } from "@babel/helper-skip-transparent-expression-wrappers";
+import { transformOptionalChain } from "@babel/plugin-transform-optional-chaining";
+
+export default declare(api => {
+  api.assertVersion("^7.22.5");
+
+  const assumptions = {
+    noDocumentAll: api.assumption("noDocumentAll") ?? false,
+    pureGetters: api.assumption("pureGetters") ?? false,
+  };
+
+  const { types: t } = api;
+
+  return {
+    name: "transform-optional-chaining-assign",
+    inherits: syntaxOptionalChainingAssign,
+
+    visitor: {
+      AssignmentExpression(path, state) {
+        let lhs = path.get("left");
+        if (!lhs.isExpression()) return;
+        const isParenthesized =
+          lhs.node.extra?.parenthesized ||
+          t.isParenthesizedExpression(lhs.node);
+
+        lhs = skipTransparentExprWrappers(lhs) as NodePath<
+          t.LVal & t.Expression
+        >;
+        if (!lhs.isOptionalMemberExpression()) return;
+
+        let ifNullish: t.Expression = path.scope.buildUndefinedNode();
+        if (isParenthesized) {
+          ifNullish = t.callExpression(
+            state.addHelper("nullishReceiverError"),
+            [],
+          );
+          if (path.node.operator === "=") {
+            ifNullish = t.sequenceExpression([
+              t.cloneNode(path.node.right),
+              ifNullish,
+            ]);
+          }
+        }
+
+        transformOptionalChain(lhs, assumptions, path, ifNullish);
+      },
+    },
+  };
+});

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/assumption-noDocumentAll/basic/input.js

@@ -0,0 +1 @@
+a.b?.c.d?.e.f = g;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/assumption-noDocumentAll/basic/output.js

@@ -0,0 +1,2 @@
+var _a$b;
+(_a$b = a.b) == null || (_a$b = _a$b.c.d) == null ? void 0 : _a$b.e.f = g;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/assumption-noDocumentAll/call/input.js

@@ -0,0 +1 @@
+a.b?.c.d?.().e.f = g;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/assumption-noDocumentAll/call/output.js

@@ -0,0 +1,2 @@
+var _a$b, _a$b$c$d, _a$b$c;
+(_a$b = a.b) == null || (_a$b$c$d = (_a$b$c = _a$b.c).d) == null ? void 0 : _a$b$c$d.call(_a$b$c).e.f = g;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/assumption-noDocumentAll/options.json

@@ -0,0 +1,6 @@
+{
+  "assumptions": {
+    "noDocumentAll": true
+  },
+  "plugins": ["proposal-optional-chaining-assign"]
+}

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/assumption-noDocumentAll/parenthesized/exec.js

@@ -0,0 +1,13 @@
+let a = null;
+
+let evaluated = false;
+expect(() => {
+  (a?.b) = (evaluated = true);
+}).toThrow(TypeError);
+//expect(evaluated).toBe(true);
+
+evaluated = false;
+expect(() => {
+  (a?.b) += (evaluated = true);
+}).toThrow(TypeError);
+expect(evaluated).toBe(false);

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/assumption-noDocumentAll/parenthesized/input.js

@@ -0,0 +1,2 @@
+(a?.b) = c;
+(a?.b) += c;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/assumption-noDocumentAll/parenthesized/output.js

@@ -0,0 +1,3 @@
+var _a, _a2;
+(_a = a) == null ? (c, babelHelpers.nullishReceiverError()) : _a.b = c;
+(_a2 = a) == null ? babelHelpers.nullishReceiverError() : _a2.b += c;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/assumption-pureGetters/call/input.js

@@ -0,0 +1 @@
+a.b?.c.d?.().e.f = g;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/assumption-pureGetters/call/output.js

@@ -0,0 +1,2 @@
+var _a$b;
+(_a$b = a.b) === null || _a$b === void 0 || _a$b.c.d === null || _a$b.c.d === void 0 ? void 0 : _a$b.c.d().e.f = g;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/assumption-pureGetters/options.json

@@ -0,0 +1,6 @@
+{
+  "assumptions": {
+    "pureGetters": true
+  },
+  "plugins": ["proposal-optional-chaining-assign"]
+}

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/general/basic/exec.js

@@ -0,0 +1,38 @@
+let a = null;
+
+function never(i) {
+  throw new Error("This should not be evaluated " + i);
+}
+
+expect(() => {
+  a.b?.c.d?.e.f = never(1);
+}).toThrow(TypeError);
+
+a = { b: null };
+expect(() => {
+  a.b?.c.d?.e.f = never(2);
+}).not.toThrow();
+
+a = { b: { c: null } };
+expect(() => {
+  a.b?.c.d?.e.f = never(3);
+}).toThrow(TypeError);
+
+a = { b: { c: { d: null } } };
+expect(() => {
+  a.b?.c.d?.e.f = never(4);
+}).not.toThrow();
+
+a = { b: { c: { d: { e: null } } } };
+let evaluated = false;
+expect(() => {
+  a.b?.c.d?.e.f = (evaluated = true);
+}).toThrow(TypeError);
+expect(evaluated).toBe(true);
+
+a = { b: { c: { d: { e: {} } } } };
+let g = {};
+expect(() => {
+  a.b?.c.d?.e.f = g;
+}).not.toThrow();
+expect(a.b.c.d.e.f).toBe(g);

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/general/basic/input.js

@@ -0,0 +1 @@
+a.b?.c.d?.e.f = g;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/general/basic/output.js

@@ -0,0 +1,2 @@
+var _a$b;
+(_a$b = a.b) === null || _a$b === void 0 || (_a$b = _a$b.c.d) === null || _a$b === void 0 ? void 0 : _a$b.e.f = g;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/general/call/input.js

@@ -0,0 +1 @@
+a.b?.c.d?.().e.f = g;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/general/call/output.js

@@ -0,0 +1,2 @@
+var _a$b, _a$b$c$d, _a$b$c;
+(_a$b = a.b) === null || _a$b === void 0 || (_a$b$c$d = (_a$b$c = _a$b.c).d) === null || _a$b$c$d === void 0 ? void 0 : _a$b$c$d.call(_a$b$c).e.f = g;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/general/parenthesized/exec.js

@@ -0,0 +1,13 @@
+let a = null;
+
+let evaluated = false;
+expect(() => {
+  (a?.b) = (evaluated = true);
+}).toThrow(TypeError);
+//expect(evaluated).toBe(true);
+
+evaluated = false;
+expect(() => {
+  (a?.b) += (evaluated = true);
+}).toThrow(TypeError);
+expect(evaluated).toBe(false);

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/general/parenthesized/input.js

@@ -0,0 +1,2 @@
+(a?.b) = c;
+(a?.b) += c;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/general/parenthesized/output.js

@@ -0,0 +1,3 @@
+var _a, _a2;
+(_a = a) === null || _a === void 0 ? (c, babelHelpers.nullishReceiverError()) : _a.b = c;
+(_a2 = a) === null || _a2 === void 0 ? babelHelpers.nullishReceiverError() : _a2.b += c;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/general/plus-eq/exec.js

@@ -0,0 +1,6 @@
+let obj = null;
+expect(obj?.x += 3).toBe(undefined);
+
+obj = { x: 1 };
+expect(obj?.x += 3).toBe(4);
+expect(obj.x).toBe(4);

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/general/plus-eq/input.js

@@ -0,0 +1 @@
+a?.b.c?.d.e += 3;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/general/plus-eq/output.js

@@ -0,0 +1,2 @@
+var _a;
+(_a = a) === null || _a === void 0 || (_a = _a.b.c) === null || _a === void 0 ? void 0 : _a.d.e += 3;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/invalid/optional-call-lhs/input.js

@@ -0,0 +1 @@
+a?.() = b;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/invalid/optional-call-lhs/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "a"
+}

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/invalid/unary-inc-postfix/input.js

@@ -0,0 +1 @@
+++a?.b;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/invalid/unary-inc-postfix/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "a"
+}

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/invalid/unary-inc-prefix/input.js

@@ -0,0 +1 @@
+++a?.b;

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/invalid/unary-inc-prefix/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "a"
+}

packages/babel-plugin-proposal-optional-chaining-assign/test/fixtures/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["proposal-optional-chaining-assign"]
+}

packages/babel-plugin-proposal-optional-chaining-assign/test/index.js

@@ -0,0 +1,3 @@
+import runner from "@babel/helper-plugin-test-runner";
+
+runner(import.meta.url);

packages/babel-plugin-proposal-optional-chaining-assign/test/package.json

@@ -0,0 +1 @@
+{ "type": "module" }