From 0697f726986948ef06618ef12e4534c00d890362 Mon Sep 17 00:00:00 2001
From: lumir <rpfos@naver.com>
Date: Mon, 17 Aug 2026 21:24:28 +0900
Subject: [PATCH] fix: allow additional properties in `JSONLanguageOptions`

---
 src/languages/json-language.js    |  3 +--
 src/languages/json-source-code.js |  3 +--
 src/types.ts                      | 15 +++++++++++++--
 tests/types/types.test.ts         | 18 ++++++++++++++++++
 4 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/src/languages/json-language.js b/src/languages/json-language.js
index 68f21951..a31ea092 100644
--- a/src/languages/json-language.js
+++ b/src/languages/json-language.js
@@ -18,10 +18,9 @@ import { visitorKeys } from "@humanwhocodes/momoa";
 /**
  * @import { DocumentNode, AnyNode } from "@humanwhocodes/momoa";
  * @import { Language, OkParseResult, ParseResult, File } from "@eslint/core";
+ * @import { JSONLanguageOptions } from "../types.js";
  * @typedef {OkParseResult<DocumentNode>} JSONOkParseResult
  * @typedef {ParseResult<DocumentNode>} JSONParseResult
- * @typedef {Object} JSONLanguageOptions
- * @property {boolean} [allowTrailingCommas] Whether to allow trailing commas in JSONC mode.
  */
 
 //-----------------------------------------------------------------------------
diff --git a/src/languages/json-source-code.js b/src/languages/json-source-code.js
index 2472cfd7..4d8e6b27 100644
--- a/src/languages/json-source-code.js
+++ b/src/languages/json-source-code.js
@@ -22,8 +22,7 @@ import {
 /**
  * @import { DocumentNode, AnyNode, Token, LocationRange } from "@humanwhocodes/momoa";
  * @import { FileProblem, DirectiveType, RulesConfig } from "@eslint/core";
- * @import { JSONSyntaxElement } from "../types.js";
- * @import { JSONLanguageOptions } from "./json-language.js";
+ * @import { JSONLanguageOptions, JSONSyntaxElement } from "../types.js";
  */
 
 //-----------------------------------------------------------------------------
diff --git a/src/types.ts b/src/types.ts
index 83c56b53..221d3d70 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -7,7 +7,7 @@
 // Imports
 //------------------------------------------------------------------------------
 
-import type { RuleVisitor } from "@eslint/core";
+import type { LanguageOptions, RuleVisitor } from "@eslint/core";
 import type {
 	CustomRuleDefinitionType,
 	CustomRuleTypeDefinitions,
@@ -29,7 +29,7 @@ import type {
 	AnyNode,
 	Token,
 } from "@humanwhocodes/momoa";
-import type { JSONLanguageOptions, JSONSourceCode } from "./index.js";
+import type { JSONSourceCode } from "./index.js";
 
 //------------------------------------------------------------------------------
 // Types
@@ -37,6 +37,17 @@ import type { JSONLanguageOptions, JSONSourceCode } from "./index.js";
 
 type ValueNodeParent = DocumentNode | MemberNode | ElementNode;
 
+/**
+ * Language options provided for JSON files.
+ */
+export interface JSONLanguageOptions extends LanguageOptions {
+	/**
+	 * Whether to allow trailing commas in JSONC mode.
+	 * @default false
+	 */
+	allowTrailingCommas?: boolean;
+}
+
 /**
  * A JSON syntax element, including nodes and tokens.
  */
diff --git a/tests/types/types.test.ts b/tests/types/types.test.ts
index a858a988..9ae29be3 100644
--- a/tests/types/types.test.ts
+++ b/tests/types/types.test.ts
@@ -1,5 +1,6 @@
 import json from "@eslint/json";
 import type {
+	JSONLanguageOptions,
 	JSONRuleDefinition,
 	JSONRuleVisitor,
 	JSONSourceCode,
@@ -75,6 +76,23 @@ json.configs.recommended.plugins satisfies object;
 	end: { line: 1, column: 1, offset: 1 },
 }) satisfies JSONSyntaxElement["loc"];
 
+const validLanguageOptions1: JSONLanguageOptions = {};
+const validLanguageOptions2: JSONLanguageOptions = {
+	allowTrailingCommas: true,
+};
+const validLanguageOptions3: JSONLanguageOptions = {
+	allowTrailingCommas: false,
+};
+const validLanguageOptions4: JSONLanguageOptions = {
+	allowTrailingCommas: true,
+	unknownOption: "unknown",
+};
+
+const invalidLanguageOptions1: JSONLanguageOptions = {
+	// @ts-expect-error -- Invalid value for `allowTrailingCommas`
+	allowTrailingCommas: "true",
+};
+
 (): JSONRuleDefinition => ({
 	create({ sourceCode }): JSONRuleVisitor {
 		sourceCode satisfies JSONSourceCode;