feat: support explicit resource management in no-undef-init (#19894)

Author: mdjermanovic

docs/src/rules/no-undef-init.md

@@ -54,7 +54,7 @@ let bar;
 
 :::
 
-Please note that this rule does not check `const` declarations, destructuring patterns, function parameters, and class fields.
+Please note that this rule does not check `const` declarations, `using` declarations, `await using` declarations, destructuring patterns, function parameters, and class fields.
 
 Examples of additional **correct** code for this rule:
 
@@ -65,6 +65,10 @@ Examples of additional **correct** code for this rule:
 
 const foo = undefined;
 
+using foo1 = undefined;
+
+await using foo2 = undefined;
+
 let { bar = undefined } = baz;
 
 [quux = undefined] = quuux;
@@ -159,7 +163,7 @@ Another such case is when a variable is redeclared using `var`. For example:
 function foo() {
     var x = 1;
     console.log(x); // output: 1
-    
+
     var x;
     console.log(x); // output: 1
 

lib/rules/no-undef-init.js

@@ -5,8 +5,18 @@
 
 "use strict";
 
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
 const astUtils = require("./utils/ast-utils");
 
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+const CONSTANT_BINDINGS = new Set(["const", "using", "await using"]);
+
 //------------------------------------------------------------------------------
 // Rule Definition
 //------------------------------------------------------------------------------
@@ -49,7 +59,7 @@ module.exports = {
 
 				if (
 					init === "undefined" &&
-					node.parent.kind !== "const" &&
+					!CONSTANT_BINDINGS.has(node.parent.kind) &&
 					!shadowed
 				) {
 					context.report({

tests/lib/rules/no-undef-init.js

@@ -22,6 +22,14 @@ ruleTester.run("no-undef-init", rule, {
 	valid: [
 		"var a;",
 		{ code: "const foo = undefined", languageOptions: { ecmaVersion: 6 } },
+		{
+			code: "using foo = undefined",
+			languageOptions: { ecmaVersion: 2026 },
+		},
+		{
+			code: "await using foo = undefined",
+			languageOptions: { ecmaVersion: 2026 },
+		},
 		"var undefined = 5; var foo = undefined;",
 
 		// doesn't apply to class fields