Add option to auto-remove unused lint-deps exceptions

ts/util/lint/linter.ts

@@ -10,7 +10,7 @@ import FastGlob from 'fast-glob';
 
 import type { ExceptionType, RuleType } from './types';
 import { REASONS } from './types';
-import { ENCODING, loadJSON, sortExceptions } from './util';
+import { ENCODING, loadJSON, sortExceptions, writeExceptions } from './util';
 
 const ALL_REASONS = REASONS.join('|');
 
@@ -321,7 +321,11 @@ function setupRules(allRules: Array<RuleType>) {
   });
 }
 
-async function main(): Promise<void> {
+async function main(argv: ReadonlyArray<string>): Promise<void> {
+  const shouldRemoveUnusedExceptions = argv.includes(
+    '--remove-unused-exceptions'
+  );
+
   const now = new Date();
 
   const rules: Array<RuleType> = loadJSON(rulesPath);
@@ -393,10 +397,26 @@ async function main(): Promise<void> {
     { concurrency: 100 }
   );
 
+  let unusedExceptionsLogMessage: string;
+
+  if (shouldRemoveUnusedExceptions && unusedExceptions.length) {
+    unusedExceptionsLogMessage = `${unusedExceptions.length} unused exceptions (automatically removed),`;
+
+    const unusedExceptionsSet = new Set(unusedExceptions);
+    const newExceptions = exceptions.filter(
+      exception => !unusedExceptionsSet.has(exception)
+    );
+    writeExceptions(exceptionsPath, newExceptions);
+
+    unusedExceptions = [];
+  } else {
+    unusedExceptionsLogMessage = `${unusedExceptions.length} unused exceptions,`;
+  }
+
   console.log(
     `${scannedCount} files scanned.`,
     `${results.length} questionable lines,`,
-    `${unusedExceptions.length} unused exceptions,`,
+    unusedExceptionsLogMessage,
     `${exceptions.length} total exceptions.`
   );
 
@@ -410,14 +430,16 @@ async function main(): Promise<void> {
 
   if (unusedExceptions.length) {
     console.log();
-    console.log('Unused exceptions!');
+    console.log(
+      'Unused exceptions! Run with --remove-unused-exceptions to automatically remove them.'
+    );
     console.log(JSON.stringify(sortExceptions(unusedExceptions), null, '  '));
   }
 
   process.exit(1);
 }
 
-main().catch(err => {
+main(process.argv).catch(err => {
   console.error(err);
   process.exit(1);
 });

ts/util/lint/sort_exceptions.ts

@@ -1,15 +1,12 @@
-// Copyright 2018-2020 Signal Messenger, LLC
+// Copyright 2018-2022 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
 import { join } from 'path';
-import { writeFileSync } from 'fs';
 
 import type { ExceptionType } from './types';
-import { loadJSON, sortExceptions } from './util';
+import { loadJSON, writeExceptions } from './util';
 
 const exceptionsPath = join(__dirname, 'exceptions.json');
 const exceptions: Array<ExceptionType> = loadJSON(exceptionsPath);
 
-const sorted = sortExceptions(exceptions);
+writeExceptions(exceptionsPath, exceptions);
-
-writeFileSync(exceptionsPath, JSON.stringify(sorted, null, '  '));

ts/util/lint/util.ts

@@ -1,43 +1,28 @@
-// Copyright 2018-2021 Signal Messenger, LLC
+// Copyright 2018-2022 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
-/* eslint-disable no-console */
+import { readJsonSync, writeJsonSync } from 'fs-extra';
 
-import { readFileSync } from 'fs';
+import { orderBy } from 'lodash';
-
-import { omit, orderBy } from 'lodash';
 
 import type { ExceptionType } from './types';
 
 export const ENCODING = 'utf8';
 
-export function loadJSON<T>(target: string): T {
+export const loadJSON = <T>(path: string): T => readJsonSync(path);
-  try {
-    const contents = readFileSync(target, ENCODING);
 
-    return JSON.parse(contents);
+export const writeExceptions = (
-  } catch (error) {
+  path: string,
-    console.log(`Error loading JSON from ${target}: ${error.stack}`);
+  exceptions: ReadonlyArray<ExceptionType>
-    throw error;
+): void => writeJsonSync(path, sortExceptions(exceptions), { spaces: 2 });
-  }
-}
 
-export function sortExceptions(
+export const sortExceptions = (
-  exceptions: Array<ExceptionType>
+  exceptions: ReadonlyArray<ExceptionType>
-): Array<ExceptionType> {
+): Array<ExceptionType> =>
-  return orderBy(exceptions, [
+  orderBy(exceptions, [
     'path',
     'rule',
     'reasonCategory',
     'updated',
     'reasonDetail',
-  ]).map(removeLegacyAttributes);
+  ]);
-}
-
-// This is here in case any open changesets still touch `lineNumber`. We should remove
-//   this after 2021-06-01 to be conservative.
-function removeLegacyAttributes(
-  exception: Readonly<ExceptionType>
-): ExceptionType {
-  return omit(exception, ['lineNumber']);
-}