feat: use LinterHost for linting

.changeset/curvy-socks-buy.md

@@ -0,0 +1,8 @@
+---
+"@flint.fyi/rule-tester": minor
+"@flint.fyi/core": minor
+"@flint.fyi/cli": minor
+"@flint.fyi/typescript-language": minor
+---
+
+feat: use LinterHost for linting

packages/browser/src/rules/ruleTester.ts

@@ -1,8 +1,15 @@
 import { RuleTester } from "@flint.fyi/rule-tester";
+import { createRuleTesterTSConfig } from "@flint.fyi/typescript-language";
 import { describe, it } from "vitest";
 
 export const ruleTester = new RuleTester({
-	defaults: { fileName: "file.ts" },
+	defaults: {
+		fileName: "file.ts",
+		files: createRuleTesterTSConfig({
+			lib: ["esnext", "DOM"],
+		}),
+	},
 	describe,
+	diskBackedFSRoot: import.meta.dirname,
 	it,
 });

packages/browser/tsconfig.test.json

@@ -3,7 +3,7 @@
 		"tsBuildInfoFile": "node_modules/.cache/tsbuild/info.test.json",
 		"rootDir": "src/",
 		"outDir": "node_modules/.cache/tsbuild/test",
-		"types": []
+		"types": ["node"]
 	},
 	"extends": "../../tsconfig.base.json",
 	"include": ["src/**/*.test.ts", "src/rules/ruleTester.ts"],

packages/cli/src/runCliOnce.ts

@@ -1,4 +1,10 @@
-import { isConfig, runConfig, runConfigFixing } from "@flint.fyi/core";
+import {
+	createDiskBackedLinterHost,
+	createEphemeralLinterHost,
+	isConfig,
+	runConfig,
+	runConfigFixing,
+} from "@flint.fyi/core";
 import { debugForFile } from "debug-for-file";
 import path from "node:path";
 import { pathToFileURL } from "node:url";
@@ -37,13 +43,18 @@ export async function runCliOnce(
 	const ignoreCache = !!values["cache-ignore"];
 
 	const skipDiagnostics = !!values["skip-diagnostics"];
+
+	const host = createEphemeralLinterHost(
+		createDiskBackedLinterHost(process.cwd()),
+	);
+
 	const lintResults = await (values.fix
-		? runConfigFixing(configDefinition, {
+		? runConfigFixing(configDefinition, host, {
 				ignoreCache,
 				requestedSuggestions: new Set(values["fix-suggestions"]),
 				skipDiagnostics,
 			})
-		: runConfig(configDefinition, { ignoreCache, skipDiagnostics }));
+		: runConfig(configDefinition, host, { ignoreCache, skipDiagnostics }));
 
 	// TODO: Eventually, it'd be nice to move everything fully in-memory.
 	// This would be better for performance to avoid excess file system I/O.

packages/core/src/host/createEphemeralLinterHost.ts

@@ -0,0 +1,27 @@
+import type { LinterHost } from "../types/host.ts";
+
+/**
+ * Creates a one-shot `LinterHost` that disables file/directory watching.
+ *
+ * Useful for single-run linting (e.g. CLI execution, rule tester),
+ * where persistent watchers are unnecessary and can affect performance.
+ */
+export function createEphemeralLinterHost(baseHost: LinterHost): LinterHost {
+	return {
+		...baseHost,
+		watchDirectory() {
+			return {
+				[Symbol.dispose]() {
+					// Intentionally empty to satisfy the Disposable interface.
+				},
+			};
+		},
+		watchFile() {
+			return {
+				[Symbol.dispose]() {
+					// Intentionally empty to satisfy the Disposable interface.
+				},
+			};
+		},
+	};
+}

packages/core/src/index.ts

@@ -7,6 +7,7 @@ export { DirectivesCollector } from "./directives/DirectivesCollector.ts";
 export { directiveReports } from "./directives/reports/directiveReports.ts";
 export { globs } from "./globs/index.ts";
 export { createDiskBackedLinterHost } from "./host/createDiskBackedLinterHost.ts";
+export { createEphemeralLinterHost } from "./host/createEphemeralLinterHost.ts";
 export {
 	createVFSLinterHost,
 	type CreateVFSLinterHostOpts,

packages/core/src/languages/createLanguage.ts

@@ -18,13 +18,13 @@ export function createLanguage<AstNodesByName, FileServices extends object>(
 	const language: Language<AstNodesByName, FileServices> = {
 		...languageDefinition,
 
-		createFileFactory() {
+		createFileFactory(host) {
 			log(
 				"Creating file factory for language: %s",
 				languageDefinition.about.name,
 			);
 
-			const fileFactoryDefinition = languageDefinition.createFileFactory();
+			const fileFactoryDefinition = languageDefinition.createFileFactory(host);
 
 			log("Created file factory.");
 

packages/core/src/languages/makeDisposable.ts

@@ -1,8 +1,8 @@
 export function makeDisposable<T extends object>(obj: T): Disposable & T {
 	return {
-		...obj,
 		[Symbol.dispose]: () => () => {
 			// Intentionally empty to satisfy the Disposable interface.
 		},
+		...obj,
 	};
 }

packages/core/src/running/collectFilesAndMetadata.ts

@@ -3,6 +3,7 @@ import { nullThrows } from "@flint.fyi/utils";
 import { readFromCache } from "../cache/readFromCache.ts";
 import type { FileCacheStorage } from "../types/cache.ts";
 import type { ProcessedConfigDefinition } from "../types/configs.ts";
+import type { LinterHost } from "../types/host.ts";
 import type { AnyRule } from "../types/rules.ts";
 import { collectLanguageMetadataByFilePath } from "./collectLanguageMetadataByFilePath.ts";
 import { collectRulesOptionsByFile } from "./collectRulesOptionsByFile.ts";
@@ -45,6 +46,7 @@ export interface CollectedFilesAndMetadata {
 // Also, what if we removed the concept of a virtual file...?
 export async function collectFilesAndMetadata(
 	configDefinition: ProcessedConfigDefinition,
+	host: LinterHost,
 	ignoreCache: boolean | undefined,
 ): Promise<CollectedFilesAndMetadata> {
 	// 1. Collect all file paths to lint and the 'use' rule configuration groups
@@ -63,6 +65,7 @@ export async function collectFilesAndMetadata(
 	const languageFileMetadataByFilePath = collectLanguageMetadataByFilePath(
 		cached,
 		rulesOptionsByFile,
+		host,
 	);
 
 	// 5. Join language metadata files into the corresponding options by file path

packages/core/src/running/collectLanguageMetadataByFilePath.ts

@@ -2,6 +2,7 @@ import { makeAbsolute } from "@flint.fyi/utils";
 import { CachedFactory } from "cached-factory";
 
 import type { FileCacheStorage } from "../types/cache.ts";
+import type { LinterHost } from "../types/host.ts";
 import type {
 	AnyLanguage,
 	AnyLanguageFileMetadata,
@@ -11,6 +12,7 @@ import type { AnyRule } from "../types/rules.ts";
 export function collectLanguageMetadataByFilePath(
 	cached: Map<string, FileCacheStorage> | undefined,
 	rulesOptionsByFile: Map<AnyRule, Map<string, unknown>>,
+	host: LinterHost,
 ) {
 	const languageFileMetadataByFilePath = new CachedFactory<
 		string,
@@ -19,7 +21,7 @@ export function collectLanguageMetadataByFilePath(
 
 	const languageFilesMetadataByLanguage = new CachedFactory(
 		(language: AnyLanguage) => {
-			const fileFactory = language.createFileFactory();
+			const fileFactory = language.createFileFactory(host);
 
 			return new CachedFactory((filePath: string) =>
 				fileFactory.prepareFromDisk({

packages/core/src/running/runConfig.ts

@@ -2,6 +2,7 @@ import { CachedFactory } from "cached-factory";
 
 import { writeToCache } from "../cache/writeToCache.ts";
 import type { ProcessedConfigDefinition } from "../types/configs.ts";
+import type { LinterHost } from "../types/host.ts";
 import type { LintResults } from "../types/linting.ts";
 import type { FileReport } from "../types/reports.ts";
 import type { AnyRule } from "../types/rules.ts";
@@ -17,6 +18,7 @@ export interface RunConfigOptions {
 
 export async function runConfig(
 	configDefinition: ProcessedConfigDefinition,
+	host: LinterHost,
 	{ ignoreCache, skipDiagnostics }: RunConfigOptions,
 ): Promise<LintResults> {
 	// 1. Based on the original config definition, collect:
@@ -29,7 +31,7 @@ export async function runConfig(
 		cached,
 		languageFileMetadataByFilePath,
 		rulesFilesAndOptionsByRule,
-	} = await collectFilesAndMetadata(configDefinition, ignoreCache);
+	} = await collectFilesAndMetadata(configDefinition, host, ignoreCache);
 
 	// 2. For each lint rule, run it on all files and store each file's results
 	const reportsByFilePath = await runRules(rulesFilesAndOptionsByRule);

packages/core/src/running/runConfigFixing.ts

@@ -2,6 +2,7 @@ import { debugForFile } from "debug-for-file";
 
 import { applyChangesToFiles } from "../changing/applyChangesToFiles.ts";
 import type { ProcessedConfigDefinition } from "../types/configs.ts";
+import type { LinterHost } from "../types/host.ts";
 import type { LintResultsWithChanges } from "../types/linting.ts";
 import { runConfig } from "./runConfig.ts";
 
@@ -17,6 +18,7 @@ export interface RunConfigFixingOptions {
 
 export async function runConfigFixing(
 	configDefinition: ProcessedConfigDefinition,
+	host: LinterHost,
 	{
 		ignoreCache,
 		requestedSuggestions,
@@ -38,7 +40,7 @@ export async function runConfigFixing(
 		// Why read file many time when few do trick?
 		// Or, at least it should all be virtual...
 		// https://github.com/flint-fyi/flint/issues/73
-		const lintResults = await runConfig(configDefinition, {
+		const lintResults = await runConfig(configDefinition, host, {
 			ignoreCache,
 			skipDiagnostics,
 		});

packages/core/src/types/languages.ts

@@ -1,4 +1,5 @@
 import type { CommentDirective } from "./directives.ts";
+import type { LinterHost } from "./host.ts";
 import type { FileReport } from "./reports.ts";
 import type { Rule, RuleAbout, RuleDefinition, RuleRuntime } from "./rules.ts";
 import type { AnyOptionalSchema, InferredOutputObject } from "./shapes.ts";
@@ -68,7 +69,9 @@ export interface Language<
 	AstNodesByName,
 	FileServices extends object,
 > extends LanguageDefinition<AstNodesByName, FileServices> {
-	createFileFactory(): LanguageFileFactory<AstNodesByName, FileServices>;
+	createFileFactory(
+		host: LinterHost,
+	): LanguageFileFactory<AstNodesByName, FileServices>;
 	createRule: LanguageCreateRule<AstNodesByName, FileServices>;
 }
 
@@ -91,10 +94,9 @@ export interface LanguageDefinition<
 	FileServices extends object,
 > {
 	about: LanguageAbout;
-	createFileFactory(): LanguageFileFactoryDefinition<
-		AstNodesByName,
-		FileServices
-	>;
+	createFileFactory(
+		host: LinterHost,
+	): LanguageFileFactoryDefinition<AstNodesByName, FileServices>;
 }
 
 export interface LanguageFileCacheImpacts {

packages/jsx/src/rules/ruleTester.ts

@@ -1,8 +1,9 @@
 import { RuleTester } from "@flint.fyi/rule-tester";
+import { createRuleTesterTSConfig } from "@flint.fyi/typescript-language";
 import { describe, it } from "vitest";
 
 export const ruleTester = new RuleTester({
-	defaults: { fileName: "file.tsx" },
+	defaults: { fileName: "file.tsx", files: createRuleTesterTSConfig() },
 	describe,
 	it,
 });

packages/next/tsconfig.test.json

@@ -3,7 +3,7 @@
 		"tsBuildInfoFile": "node_modules/.cache/tsbuild/info.test.json",
 		"rootDir": "src/",
 		"outDir": "node_modules/.cache/tsbuild/test",
-		"types": []
+		"types": ["node"]
 	},
 	"extends": "../../tsconfig.base.json",
 	"include": ["src/**/*.test.ts", "src/rules/ruleTester.ts"],

packages/node/src/rules/ruleTester.ts

@@ -1,8 +1,17 @@
 import { RuleTester } from "@flint.fyi/rule-tester";
+import { createRuleTesterTSConfig } from "@flint.fyi/typescript-language";
 import { describe, it } from "vitest";
 
 export const ruleTester = new RuleTester({
-	defaults: { fileName: "file.ts" },
+	defaults: {
+		fileName: "file.ts",
+		files: createRuleTesterTSConfig({
+			types: ["node"],
+			// TODO: remove this; there is a bug in blobReadingMethods - it doesn't respect type from @types/node
+			lib: ["dom"],
+		}),
+	},
 	describe,
+	diskBackedFSRoot: import.meta.dirname,
 	it,
 });

packages/node/tsconfig.test.json

@@ -3,7 +3,7 @@
 		"tsBuildInfoFile": "node_modules/.cache/tsbuild/info.test.json",
 		"rootDir": "src/",
 		"outDir": "node_modules/.cache/tsbuild/test",
-		"types": []
+		"types": ["node"]
 	},
 	"extends": "../../tsconfig.base.json",
 	"include": ["src/**/*.test.ts", "src/rules/ruleTester.ts"],

packages/performance/src/rules/ruleTester.ts

@@ -1,8 +1,12 @@
 import { RuleTester } from "@flint.fyi/rule-tester";
+import { createRuleTesterTSConfig } from "@flint.fyi/typescript-language";
 import { describe, it } from "vitest";
 
 export const ruleTester = new RuleTester({
-	defaults: { fileName: "file.ts" },
+	defaults: {
+		fileName: "file.ts",
+		files: createRuleTesterTSConfig(),
+	},
 	describe,
 	it,
 });

packages/plugin-flint/src/rules/ruleTester.ts

@@ -1,8 +1,13 @@
 import { RuleTester } from "@flint.fyi/rule-tester";
+import { createRuleTesterTSConfig } from "@flint.fyi/typescript-language";
 import { describe, it } from "vitest";
 
 export const ruleTester = new RuleTester({
-	defaults: { fileName: "file.test.ts" },
+	defaults: {
+		fileName: "file.test.ts",
+		files: createRuleTesterTSConfig(),
+	},
 	describe,
+	diskBackedFSRoot: import.meta.dirname,
 	it,
 });

packages/plugin-flint/tsconfig.test.json

@@ -3,7 +3,7 @@
 		"tsBuildInfoFile": "node_modules/.cache/tsbuild/info.test.json",
 		"rootDir": "src/",
 		"outDir": "node_modules/.cache/tsbuild/test",
-		"types": []
+		"types": ["node"]
 	},
 	"extends": "../../tsconfig.base.json",
 	"include": ["src/**/*.test.ts", "src/rules/ruleTester.ts"],