Revert "Remove legacy rule function form"

This reverts commit e053179.

packages/rule-tester/src/RuleTester.ts

@@ -9,6 +9,7 @@ import type * as ParserType from '@typescript-eslint/parser';
 import type { TSESTree } from '@typescript-eslint/utils';
 import { deepMerge } from '@typescript-eslint/utils/eslint-utils';
 import type {
+  AnyRuleCreateFunction,
   AnyRuleModule,
   Parser,
   ParserOptions,
@@ -74,7 +75,7 @@ let defaultConfig = deepMerge(
 
 export class RuleTester extends TestFramework {
   readonly #testerConfig: TesterConfigWithDefaults;
-  readonly #rules: Record<string, AnyRuleModule> = {};
+  readonly #rules: Record<string, AnyRuleCreateFunction | AnyRuleModule> = {};
   readonly #linter: Linter = new Linter({ configType: 'eslintrc' });
 
   /**
@@ -170,7 +171,7 @@ export class RuleTester extends TestFramework {
   /**
    * Define a rule for one particular run of tests.
    */
-  defineRule(name: string, rule: AnyRuleModule): void {
+  defineRule(name: string, rule: AnyRuleCreateFunction | AnyRuleModule): void {
     this.#rules[name] = rule;
   }
 

packages/utils/src/eslint-utils/InferTypesFromRule.ts

@@ -1,17 +1,23 @@
-import type { RuleModule } from '../ts-eslint';
+import type { RuleCreateFunction, RuleModule } from '../ts-eslint';
 
 /**
  * Uses type inference to fetch the Options type from the given RuleModule
  */
 type InferOptionsTypeFromRule<T> =
-  T extends RuleModule<infer _MessageIds, infer Options> ? Options : unknown;
+  T extends RuleModule<infer _MessageIds, infer Options>
+    ? Options
+    : T extends RuleCreateFunction<infer _MessageIds, infer Options>
+      ? Options
+      : unknown;
 
 /**
  * Uses type inference to fetch the MessageIds type from the given RuleModule
  */
 type InferMessageIdsTypeFromRule<T> =
   T extends RuleModule<infer MessageIds, infer _TOptions>
     ? MessageIds
-    : unknown;
+    : T extends RuleCreateFunction<infer MessageIds, infer _TOptions>
+      ? MessageIds
+      : unknown;
 
 export { InferOptionsTypeFromRule, InferMessageIdsTypeFromRule };

packages/utils/src/ts-eslint/Linter.ts

@@ -5,7 +5,13 @@ import { Linter as ESLintLinter } from 'eslint';
 import type { ClassicConfig, FlatConfig, SharedConfig } from './Config';
 import type { Parser } from './Parser';
 import type { Processor as ProcessorType } from './Processor';
-import type { AnyRuleModule, RuleFix, RuleModule } from './Rule';
+import type {
+  AnyRuleCreateFunction,
+  AnyRuleModule,
+  RuleCreateFunction,
+  RuleFix,
+  RuleModule,
+} from './Rule';
 import type { SourceCode } from './SourceCode';
 
 export type MinimalRuleModule<
@@ -35,15 +41,19 @@ declare class LinterBase {
    */
   defineRule<MessageIds extends string, Options extends readonly unknown[]>(
     ruleId: string,
-    ruleModule: MinimalRuleModule<MessageIds, Options>,
+    ruleModule: MinimalRuleModule<MessageIds, Options> | RuleCreateFunction,
   ): void;
 
   /**
    * Defines many new linting rules.
    * @param rulesToDefine map from unique rule identifier to rule
    */
   defineRules<MessageIds extends string, Options extends readonly unknown[]>(
-    rulesToDefine: Record<string, MinimalRuleModule<MessageIds, Options>>,
+    rulesToDefine: Record<
+      string,
+      | MinimalRuleModule<MessageIds, Options>
+      | RuleCreateFunction<MessageIds, Options>
+    >,
   ): void;
 
   /**
@@ -266,6 +276,11 @@ namespace Linter {
     parserOptions?: ParserOptions;
   }
 
+  // TODO - RuleCreateFunction is no longer supported in ESLint v9
+  export type LegacyPluginRules = Record<
+    string,
+    AnyRuleCreateFunction | AnyRuleModule
+  >;
   export type PluginRules = Record<string, AnyRuleModule>;
 
   export interface Plugin {
@@ -288,7 +303,7 @@ namespace Linter {
     /**
      * The definition of plugin rules.
      */
-    rules?: PluginRules;
+    rules?: LegacyPluginRules;
   }
 }
 

packages/utils/src/ts-eslint/Rule.ts

@@ -663,10 +663,13 @@ export type AnyRuleModule = RuleModule<string, readonly unknown[]>;
  *
  * @see {@link LooseParserModule}, {@link LooseProcessorModule}
  */
-export interface LooseRuleDefinition {
-  meta?: object | undefined;
-  create: LooseRuleCreateFunction;
-}
+export type LooseRuleDefinition =
+  // TODO - ESLint v9 will remove support for RuleCreateFunction
+  | LooseRuleCreateFunction
+  | {
+      meta?: object | undefined;
+      create: LooseRuleCreateFunction;
+    };
 /*
 eslint-disable-next-line @typescript-eslint/no-explicit-any --
 intentionally using `any` to allow bi-directional assignment (unknown and
@@ -682,3 +685,12 @@ export type LooseRuleCreateFunction = (context: any) => Record<
   */
   Function | undefined
 >;
+
+export type RuleCreateFunction<
+  MessageIds extends string = never,
+  Options extends readonly unknown[] = unknown[],
+> = (context: Readonly<RuleContext<MessageIds, Options>>) => RuleListener;
+export type AnyRuleCreateFunction = RuleCreateFunction<
+  string,
+  readonly unknown[]
+>;

packages/utils/src/ts-eslint/RuleTester.ts

@@ -6,6 +6,7 @@ import type { Linter } from './Linter';
 import type { ParserOptions } from './ParserOptions';
 import type {
   ReportDescriptorMessageData,
+  RuleCreateFunction,
   RuleModule,
   SharedConfigurationSettings,
 } from './Rule';
@@ -191,7 +192,9 @@ declare class RuleTesterBase {
    */
   defineRule<MessageIds extends string, Options extends Readonly<unknown[]>>(
     name: string,
-    rule: RuleModule<MessageIds, Options>,
+    rule:
+      | RuleCreateFunction<MessageIds, Options>
+      | RuleModule<MessageIds, Options>,
   ): void;
 }