Add Swift to yarn format

Summary:
Add `yarn format-swift` and `yarn format-check-swift` using Apple swift-format, and compose them into the repository-wide commands. The wrapper selects a repository-provided formatter when available or uses swift-format 6.3 or newer from the Swift toolchain. Missing tools produce environment-specific setup guidance before Swift is skipped.

Changelog: [Internal]

Differential Revision: D119487615

Author: cortinico

.swift-format

@@ -0,0 +1,81 @@
+{
+  "fileScopedDeclarationPrivacy": {
+    "accessLevel": "private"
+  },
+  "indentConditionalCompilationBlocks": false,
+  "indentSwitchCaseLabels": false,
+  "indentation": {
+    "spaces": 2
+  },
+  "lineBreakAroundMultilineExpressionChainComponents": false,
+  "lineBreakBeforeControlFlowKeywords": false,
+  "lineBreakBeforeEachArgument": false,
+  "lineBreakBeforeEachGenericRequirement": false,
+  "lineBreakBetweenDeclarationAttributes": false,
+  "lineLength": 2000,
+  "maximumBlankLines": 1,
+  "multiElementCollectionTrailingCommas": true,
+  "orderedImports": {
+    "includeConditionalImports": false,
+    "shouldGroupImports": false
+  },
+  "noAssignmentInExpressions": {
+    "allowedFunctions": [
+      "XCTAssertNoThrow"
+    ]
+  },
+  "prioritizeKeepingFunctionOutputTogether": true,
+  "reflowMultilineStringLiterals": {
+    "never": {}
+  },
+  "respectsExistingLineBreaks": true,
+  "rules": {
+    "AllPublicDeclarationsHaveDocumentation": false,
+    "AlwaysUseLiteralForEmptyCollectionInit": false,
+    "AlwaysUseLowerCamelCase": false,
+    "AmbiguousTrailingClosureOverload": false,
+    "AvoidRetroactiveConformances": false,
+    "BeginDocumentationCommentWithOneLineSummary": false,
+    "DoNotUseSemicolons": true,
+    "DontRepeatTypeInStaticProperties": false,
+    "FileScopedDeclarationPrivacy": false,
+    "FullyIndirectEnum": false,
+    "GroupNumericLiterals": false,
+    "IdentifiersMustBeASCII": false,
+    "NeverForceUnwrap": false,
+    "NeverUseForceTry": false,
+    "NeverUseImplicitlyUnwrappedOptionals": false,
+    "NoAccessLevelOnExtensionDeclaration": false,
+    "NoAssignmentInExpressions": true,
+    "NoBlockComments": false,
+    "NoCasesWithOnlyFallthrough": false,
+    "NoEmptyLinesOpeningClosingBraces": false,
+    "NoEmptyTrailingClosureParentheses": false,
+    "NoLabelsInCasePatterns": false,
+    "NoLeadingUnderscores": false,
+    "NoParensAroundConditions": true,
+    "NoPlaygroundLiterals": false,
+    "NoVoidReturnOnFunctionSignature": true,
+    "OmitExplicitReturns": false,
+    "OneCasePerLine": false,
+    "OneVariableDeclarationPerLine": true,
+    "OnlyOneTrailingClosureArgument": false,
+    "OrderedImports": true,
+    "ReplaceForEachWithForLoop": false,
+    "ReturnVoidInsteadOfEmptyTuple": true,
+    "TypeNamesShouldBeCapitalized": false,
+    "UseEarlyExits": false,
+    "UseExplicitNilCheckInConditions": false,
+    "UseLetInEveryBoundCaseVariable": false,
+    "UseShorthandTypeNames": false,
+    "UseSingleLinePropertyGetter": false,
+    "UseSynthesizedInitializer": false,
+    "UseTripleSlashForDocumentationComments": false,
+    "UseWhereClausesInForLoops": false,
+    "ValidateDocumentationComments": false
+  },
+  "spacesAroundRangeFormationOperators": false,
+  "spacesBeforeEndOfLineComments": 1,
+  "tabWidth": 8,
+  "version": 1
+}

package.json

@@ -14,18 +14,20 @@
     "cxx-api-validate": "python -m scripts.cxx-api.parser --validate",
     "flow-check": "flow full-check",
     "flow": "flow",
-    "format-check": "yarn format-check-javascript && yarn format-check-cpp && yarn format-check-kotlin && yarn format-check-java && yarn format-check-python",
+    "format-check": "yarn format-check-javascript && yarn format-check-cpp && yarn format-check-kotlin && yarn format-check-java && yarn format-check-python && yarn format-check-swift",
     "format-check-cpp": "node ./scripts/clang-format.js --check",
     "format-check-java": "node ./scripts/format-java.js --check",
     "format-check-javascript": "prettier --check \"./**/*.{cjs,cts,flow,js,jsx,md,mjs,mts,ts,tsx,yaml,yml}\"",
     "format-check-kotlin": "node ./scripts/format-kotlin.js --check",
     "format-check-python": "node ./scripts/format-python.js --check",
-    "format": "yarn format-javascript && yarn format-cpp && yarn format-kotlin && yarn format-java && yarn format-python",
+    "format-check-swift": "node ./scripts/format-swift.js --check",
+    "format": "yarn format-javascript && yarn format-cpp && yarn format-kotlin && yarn format-java && yarn format-python && yarn format-swift",
     "format-cpp": "node ./scripts/clang-format.js",
     "format-java": "node ./scripts/format-java.js",
     "format-javascript": "prettier --write \"./**/*.{cjs,cts,flow,js,jsx,md,mjs,mts,ts,tsx,yaml,yml}\"",
     "format-kotlin": "node ./scripts/format-kotlin.js",
     "format-python": "node ./scripts/format-python.js",
+    "format-swift": "node ./scripts/format-swift.js",
     "featureflags": "yarn --cwd packages/react-native featureflags",
     "js-api-diff": "node ./scripts/js-api/diff-api-snapshot",
     "lint-markdown": "markdownlint-cli2 2>&1",

scripts/format-swift.js

@@ -0,0 +1,121 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @noflow
+ * @format
+ */
+
+'use strict';
+
+const {
+  IS_META_CHECKOUT,
+  commandVersion,
+  findMetaTool,
+} = require('./format-utils');
+const {spawnSync} = require('node:child_process');
+const fs = require('node:fs');
+const path = require('node:path');
+const {globSync} = require('tinyglobby');
+
+const REPO_ROOT = path.resolve(__dirname, '..');
+const CONFIG = path.join(REPO_ROOT, '.swift-format');
+const GENERATED_MARKER = Buffer.from('@' + 'generated');
+const MINIMUM_SWIFT_FORMAT_MAJOR = 6;
+const MINIMUM_SWIFT_FORMAT_MINOR = 3;
+const MAX_FILES_PER_PROCESS = 100;
+const MAX_HEADER_BYTES = 4096;
+const IGNORE = ['**/Pods/**', '**/build/**', '**/node_modules/**'];
+
+function isGenerated(file) {
+  const fd = fs.openSync(path.resolve(REPO_ROOT, file), 'r');
+  try {
+    const header = Buffer.alloc(MAX_HEADER_BYTES);
+    const bytesRead = fs.readSync(fd, header, 0, header.length, 0);
+    return header.subarray(0, bytesRead).includes(GENERATED_MARKER);
+  } finally {
+    fs.closeSync(fd);
+  }
+}
+
+function findSwiftFormat() {
+  const candidates = [];
+  if (process.env.SWIFT_FORMAT != null) {
+    candidates.push([process.env.SWIFT_FORMAT, []]);
+  } else {
+    const metaSwiftFormat = findMetaTool(
+      'tools',
+      'lint',
+      'swift-format',
+      'swift-format',
+    );
+    if (metaSwiftFormat != null) {
+      candidates.push([
+        metaSwiftFormat.command,
+        metaSwiftFormat.prefixArguments,
+      ]);
+    }
+    candidates.push(['swift-format', []], ['swift', ['format']]);
+  }
+  for (const [command, prefixArguments] of candidates) {
+    const result = commandVersion(command, prefixArguments);
+    const version = /(\d+)\.(\d+)(?:\.\d+)?/.exec(result.output);
+    if (
+      result.status === 0 &&
+      version != null &&
+      (Number(version[1]) > MINIMUM_SWIFT_FORMAT_MAJOR ||
+        (Number(version[1]) === MINIMUM_SWIFT_FORMAT_MAJOR &&
+          Number(version[2]) >= MINIMUM_SWIFT_FORMAT_MINOR))
+    ) {
+      return {command, prefixArguments};
+    }
+  }
+  const instructions = IS_META_CHECKOUT
+    ? 'Meta: unset SWIFT_FORMAT and run `tools/lint/swift-format/swift-format --version` from the fbsource root. If that fails, repair your Meta DotSlash setup.'
+    : 'Please install Swift 6.3 or newer and make sure `swift-format` or `swift` is in your PATH, or set SWIFT_FORMAT=/path/to/swift-format.';
+  console.warn(
+    'warning: Skipping Swift formatting because swift-format 6.3 or newer was not found.\n' +
+      instructions,
+  );
+  return null;
+}
+
+function main() {
+  const check = process.argv[2] === '--check';
+  const files = globSync('**/*.swift', {cwd: REPO_ROOT, ignore: IGNORE}).filter(
+    file => !isGenerated(file),
+  );
+  const swiftFormat = findSwiftFormat();
+  if (swiftFormat == null) {
+    return;
+  }
+
+  for (let i = 0; i < files.length; i += MAX_FILES_PER_PROCESS) {
+    const result = spawnSync(
+      swiftFormat.command,
+      [
+        ...swiftFormat.prefixArguments,
+        check ? 'lint' : 'format',
+        '--configuration',
+        CONFIG,
+        ...(check ? ['--strict'] : ['--in-place']),
+        ...files.slice(i, i + MAX_FILES_PER_PROCESS),
+      ],
+      {cwd: REPO_ROOT, stdio: 'inherit'},
+    );
+    if (result.error != null) {
+      throw result.error;
+    }
+    if (result.signal != null) {
+      process.kill(process.pid, result.signal);
+      return;
+    }
+    if (result.status !== 0) {
+      process.exit(result.status ?? 1);
+    }
+  }
+}
+
+main();