feat: Add support for ES2026 using and await using declarations (#658)

* feat: Add support for ES2026 `using` and `await using` declarations

* Update packages/espree/README.md

Co-authored-by: Milos Djermanovic <[email protected]>

* docs: update

---------

Co-authored-by: Milos Djermanovic <[email protected]>

Author: ota-meshi

packages/eslint-scope/tests/using-scope.js

@@ -0,0 +1,69 @@
+/**
+ * @fileoverview Tests for ES2026 `using` and `await using`.
+ * @author Yosuke Ota
+ */
+
+import { expect } from "chai";
+import * as espree from "espree";
+import { analyze } from "../lib/index.js";
+
+describe("`using` and `await using` block scope", () => {
+    it("`using` in block scope", () => {
+        const ast = espree.parse(`
+            {
+                using i = 42;
+                i;
+            }
+        `, { ecmaVersion: 2026 });
+
+        const scopeManager = analyze(ast, { ecmaVersion: 2026 });
+
+        expect(scopeManager.scopes).to.have.length(2); // Program and BlockStatement scope.
+
+        let scope = scopeManager.scopes[0];
+
+        expect(scope.type).to.be.equal("global");
+        expect(scope.variables).to.have.length(0);
+
+        scope = scopeManager.scopes[1];
+        expect(scope.type).to.be.equal("block");
+        expect(scope.variables).to.have.length(1);
+        expect(scope.variables[0].name).to.be.equal("i");
+        expect(scope.references).to.have.length(2);
+        expect(scope.references[0].identifier.name).to.be.equal("i");
+        expect(scope.references[1].identifier.name).to.be.equal("i");
+    });
+    it("`await using` in block scope", () => {
+        const ast = espree.parse(`
+            async function fn() {
+                {
+                    await using i = 42;
+                    i;
+                }
+            }
+        `, { ecmaVersion: 2026 });
+
+        const scopeManager = analyze(ast, { ecmaVersion: 2026 });
+
+        expect(scopeManager.scopes).to.have.length(3); // Program, Function, and BlockStatement scope.
+
+        let scope = scopeManager.scopes[0];
+
+        expect(scope.type).to.be.equal("global");
+        expect(scope.variables).to.have.length(1);
+        expect(scope.variables[0].name).to.be.equal("fn");
+
+        scope = scopeManager.scopes[1];
+        expect(scope.type).to.be.equal("function");
+        expect(scope.variables).to.have.length(1);
+        expect(scope.variables[0].name).to.be.equal("arguments");
+
+        scope = scopeManager.scopes[2];
+        expect(scope.type).to.be.equal("block");
+        expect(scope.variables).to.have.length(1);
+        expect(scope.variables[0].name).to.be.equal("i");
+        expect(scope.references).to.have.length(2);
+        expect(scope.references[0].identifier.name).to.be.equal("i");
+        expect(scope.references[1].identifier.name).to.be.equal("i");
+    });
+});

packages/espree/README.md

@@ -140,8 +140,8 @@ const options = {
     // create a top-level tokens array containing all tokens
     tokens: false,
 
-    // Set to 3, 5 (the default), 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16 to specify the version of ECMAScript syntax you want to use.
-    // You can also set to 2015 (same as 6), 2016 (same as 7), 2017 (same as 8), 2018 (same as 9), 2019 (same as 10), 2020 (same as 11), 2021 (same as 12), 2022 (same as 13), 2023 (same as 14), 2024 (same as 15) or 2025 (same as 16) to use the year-based naming.
+    // Set to 3, 5 (the default), 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or 17 to specify the version of ECMAScript syntax you want to use.
+    // You can also set to 2015 (same as 6), 2016 (same as 7), 2017 (same as 8), 2018 (same as 9), 2019 (same as 10), 2020 (same as 11), 2021 (same as 12), 2022 (same as 13), 2023 (same as 14), 2024 (same as 15), 2025 (same as 16) or 2026 (same as 17) to use the year-based naming.
     // You can also set "latest" to use the most recently supported version.
     ecmaVersion: 3,
 
@@ -231,13 +231,11 @@ We are building on top of Acorn, however, so that we can contribute back and hel
 
 ### What ECMAScript features do you support?
 
-Espree supports all ECMAScript 2024 features and partially supports ECMAScript 2025 features.
+Espree supports all ECMAScript 2025 features and partially supports ECMAScript 2026 features.
 
-Because ECMAScript 2025 is still under development, we are implementing features as they are finalized. Currently, Espree supports:
+Because ECMAScript 2026 is still under development, we are implementing features as they are finalized. Currently, Espree supports:
 
-* [RegExp Duplicate named capturing groups](https://github.com/tc39/proposal-duplicate-named-capturing-groups)
-* [RegExp Pattern modifiers](https://github.com/tc39/proposal-regexp-modifiers)
-* [Import Attributes](https://github.com/tc39/proposal-import-attributes)
+* [Explicit Resource Management](https://github.com/tc39/proposal-explicit-resource-management)
 
 See [finished-proposals.md](https://github.com/tc39/proposals/blob/master/finished-proposals.md) to know what features are finalized.
 

packages/espree/docs/README.md

@@ -140,8 +140,8 @@ const options = {
     // create a top-level tokens array containing all tokens
     tokens: false,
 
-    // Set to 3, 5 (the default), 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16 to specify the version of ECMAScript syntax you want to use.
-    // You can also set to 2015 (same as 6), 2016 (same as 7), 2017 (same as 8), 2018 (same as 9), 2019 (same as 10), 2020 (same as 11), 2021 (same as 12), 2022 (same as 13), 2023 (same as 14), 2024 (same as 15) or 2025 (same as 16) to use the year-based naming.
+    // Set to 3, 5 (the default), 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or 17 to specify the version of ECMAScript syntax you want to use.
+    // You can also set to 2015 (same as 6), 2016 (same as 7), 2017 (same as 8), 2018 (same as 9), 2019 (same as 10), 2020 (same as 11), 2021 (same as 12), 2022 (same as 13), 2023 (same as 14), 2024 (same as 15), 2025 (same as 16) or 2026 (same as 17) to use the year-based naming.
     // You can also set "latest" to use the most recently supported version.
     ecmaVersion: 3,
 
@@ -231,13 +231,11 @@ We are building on top of Acorn, however, so that we can contribute back and hel
 
 ### What ECMAScript features do you support?
 
-Espree supports all ECMAScript 2024 features and partially supports ECMAScript 2025 features.
+Espree supports all ECMAScript 2025 features and partially supports ECMAScript 2026 features.
 
-Because ECMAScript 2025 is still under development, we are implementing features as they are finalized. Currently, Espree supports:
+Because ECMAScript 2026 is still under development, we are implementing features as they are finalized. Currently, Espree supports:
 
-* [RegExp Duplicate named capturing groups](https://github.com/tc39/proposal-duplicate-named-capturing-groups)
-* [RegExp Pattern modifiers](https://github.com/tc39/proposal-regexp-modifiers)
-* [Import Attributes](https://github.com/tc39/proposal-import-attributes)
+* [Explicit Resource Management](https://github.com/tc39/proposal-explicit-resource-management)
 
 See [finished-proposals.md](https://github.com/tc39/proposals/blob/master/finished-proposals.md) to know what features are finalized.
 

packages/espree/lib/options.js

@@ -20,7 +20,8 @@ const SUPPORTED_VERSIONS = [
     13, // 2022
     14, // 2023
     15, // 2024
-    16 // 2025
+    16, // 2025
+    17 // 2026
 ];
 
 /**

packages/espree/package.json

@@ -36,7 +36,7 @@
   "funding": "https://opencollective.com/eslint",
   "license": "BSD-2-Clause",
   "dependencies": {
-    "acorn": "^8.14.0",
+    "acorn": "^8.15.0",
     "acorn-jsx": "^5.3.2",
     "eslint-visitor-keys": "^4.2.0"
   },

packages/espree/tests/fixtures/ecma-version/11/bigint/binary.result.js

@@ -49,7 +49,7 @@ export default {
                 ],
                 "value": 0b0101n,
                 "raw": "0b0101n",
-                "bigint": "0b0101"
+                "bigint": "5"
             }
         }
     ],

packages/espree/tests/fixtures/ecma-version/11/bigint/hex.result.js

@@ -49,7 +49,7 @@ export default {
                 ],
                 "value": 0x80n,
                 "raw": "0x80n",
-                "bigint": "0x80"
+                "bigint": "128"
             }
         }
     ],

packages/espree/tests/fixtures/ecma-version/11/bigint/octal.result.js

@@ -49,7 +49,7 @@ export default {
                 ],
                 "value": 0o755n,
                 "raw": "0o755n",
-                "bigint": "0o755"
+                "bigint": "493"
             }
         }
     ],

packages/espree/tests/fixtures/ecma-version/17/explicit-resource-management/invalid-export-using.module-result.js

@@ -0,0 +1,6 @@
+export default {
+    "index": 7,
+    "lineNumber": 1,
+    "column": 8,
+    "message": "Unexpected token using"
+};

packages/espree/tests/fixtures/ecma-version/17/explicit-resource-management/invalid-export-using.result.js

@@ -0,0 +1,6 @@
+export default {
+    "index": 0,
+    "lineNumber": 1,
+    "column": 1,
+    "message": "'import' and 'export' may appear only with 'sourceType: module'"
+};