diff --git a/.eslintrc b/.eslintrc
index f8b03f98a..5bf9d4067 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -2,18 +2,38 @@
"root": true,
"extends": "next/core-web-vitals",
"parser": "@typescript-eslint/parser",
- "plugins": ["@typescript-eslint", "eslint-plugin-react-compiler"],
+ "plugins": ["@typescript-eslint", "eslint-plugin-react-compiler", "local-rules"],
"rules": {
"no-unused-vars": "off",
"@typescript-eslint/no-unused-vars": ["error", {"varsIgnorePattern": "^_"}],
"react-hooks/exhaustive-deps": "error",
"react/no-unknown-property": ["error", {"ignore": ["meta"]}],
- "react-compiler/react-compiler": "error"
+ "react-compiler/react-compiler": "error",
+ "local-rules/lint-markdown-code-blocks": "error"
},
"env": {
"node": true,
"commonjs": true,
"browser": true,
"es6": true
- }
+ },
+ "overrides": [
+ {
+ "files": ["src/content/**/*.md"],
+ "processor": "local-rules/markdown",
+ "parser": "espree",
+ "parserOptions": {
+ "ecmaVersion": "latest",
+ "sourceType": "script"
+ },
+ "rules": {
+ "no-unused-vars": "off",
+ "@typescript-eslint/no-unused-vars": "off",
+ "react-hooks/exhaustive-deps": "off",
+ "react/no-unknown-property": "off",
+ "react-compiler/react-compiler": "off",
+ "local-rules/lint-markdown-code-blocks": "error"
+ }
+ }
+ ]
}
diff --git a/eslint-local-rules/__tests__/fixtures/src/content/basic-error.md b/eslint-local-rules/__tests__/fixtures/src/content/basic-error.md
new file mode 100644
index 000000000..8e7670fdc
--- /dev/null
+++ b/eslint-local-rules/__tests__/fixtures/src/content/basic-error.md
@@ -0,0 +1,8 @@
+```jsx
+import {useState} from 'react';
+function Counter() {
+ const [count, setCount] = useState(0);
+ setCount(count + 1);
+ return
{count}
;
+}
+```
diff --git a/eslint-local-rules/__tests__/fixtures/src/content/duplicate-metadata.md b/eslint-local-rules/__tests__/fixtures/src/content/duplicate-metadata.md
new file mode 100644
index 000000000..67d6b62bb
--- /dev/null
+++ b/eslint-local-rules/__tests__/fixtures/src/content/duplicate-metadata.md
@@ -0,0 +1,8 @@
+```jsx title="Counter" {expectedErrors: {'react-compiler': [99]}} {expectedErrors: {'react-compiler': [2]}}
+import {useState} from 'react';
+function Counter() {
+ const [count, setCount] = useState(0);
+ setCount(count + 1);
+ return {count}
;
+}
+```
diff --git a/eslint-local-rules/__tests__/fixtures/src/content/malformed-metadata.md b/eslint-local-rules/__tests__/fixtures/src/content/malformed-metadata.md
new file mode 100644
index 000000000..fd542bf03
--- /dev/null
+++ b/eslint-local-rules/__tests__/fixtures/src/content/malformed-metadata.md
@@ -0,0 +1,8 @@
+```jsx {expectedErrors: {'react-compiler': 'invalid'}}
+import {useState} from 'react';
+function Counter() {
+ const [count, setCount] = useState(0);
+ setCount(count + 1);
+ return {count}
;
+}
+```
diff --git a/eslint-local-rules/__tests__/fixtures/src/content/mixed-language.md b/eslint-local-rules/__tests__/fixtures/src/content/mixed-language.md
new file mode 100644
index 000000000..313b0e30f
--- /dev/null
+++ b/eslint-local-rules/__tests__/fixtures/src/content/mixed-language.md
@@ -0,0 +1,7 @@
+```bash
+setCount()
+```
+
+```txt
+import {useState} from 'react';
+```
diff --git a/eslint-local-rules/__tests__/fixtures/src/content/stale-expected-error.md b/eslint-local-rules/__tests__/fixtures/src/content/stale-expected-error.md
new file mode 100644
index 000000000..46e330ac0
--- /dev/null
+++ b/eslint-local-rules/__tests__/fixtures/src/content/stale-expected-error.md
@@ -0,0 +1,5 @@
+```jsx {expectedErrors: {'react-compiler': [3]}}
+function Hello() {
+ return Hello
;
+}
+```
diff --git a/eslint-local-rules/__tests__/fixtures/src/content/suppressed-error.md b/eslint-local-rules/__tests__/fixtures/src/content/suppressed-error.md
new file mode 100644
index 000000000..ecefa8495
--- /dev/null
+++ b/eslint-local-rules/__tests__/fixtures/src/content/suppressed-error.md
@@ -0,0 +1,8 @@
+```jsx {expectedErrors: {'react-compiler': [4]}}
+import {useState} from 'react';
+function Counter() {
+ const [count, setCount] = useState(0);
+ setCount(count + 1);
+ return {count}
;
+}
+```
diff --git a/eslint-local-rules/__tests__/lint-markdown-code-blocks.test.js b/eslint-local-rules/__tests__/lint-markdown-code-blocks.test.js
new file mode 100644
index 000000000..90fa1c518
--- /dev/null
+++ b/eslint-local-rules/__tests__/lint-markdown-code-blocks.test.js
@@ -0,0 +1,124 @@
+const assert = require('assert');
+const fs = require('fs');
+const path = require('path');
+const {ESLint} = require('eslint');
+const plugin = require('..');
+
+const FIXTURES_DIR = path.join(
+ __dirname,
+ 'fixtures',
+ 'src',
+ 'content'
+);
+
+function createESLint({fix = false} = {}) {
+ return new ESLint({
+ useEslintrc: false,
+ fix,
+ plugins: {
+ 'local-rules': plugin,
+ },
+ overrideConfig: {
+ processor: 'local-rules/markdown',
+ plugins: ['local-rules'],
+ rules: {
+ 'local-rules/lint-markdown-code-blocks': 'error',
+ },
+ parserOptions: {
+ ecmaVersion: 2020,
+ sourceType: 'module',
+ },
+ },
+ });
+}
+
+function readFixture(name) {
+ return fs.readFileSync(path.join(FIXTURES_DIR, name), 'utf8');
+}
+
+async function lintFixture(name, {fix = false} = {}) {
+ const eslint = createESLint({fix});
+ const filePath = path.join(FIXTURES_DIR, name);
+ const markdown = readFixture(name);
+ const [result] = await eslint.lintText(markdown, {filePath});
+ return result;
+}
+
+async function run() {
+ const basicResult = await lintFixture('basic-error.md');
+ assert.strictEqual(
+ basicResult.messages.length,
+ 1,
+ 'expected one diagnostic'
+ );
+ assert(
+ basicResult.messages[0].message.includes('Calling setState during render'),
+ 'expected message to mention setState during render'
+ );
+
+ const suppressedResult = await lintFixture('suppressed-error.md');
+ assert.strictEqual(
+ suppressedResult.messages.length,
+ 0,
+ 'expected suppression metadata to silence diagnostic'
+ );
+
+ const staleResult = await lintFixture('stale-expected-error.md');
+ assert.strictEqual(
+ staleResult.messages.length,
+ 1,
+ 'expected stale metadata error'
+ );
+ assert.strictEqual(
+ staleResult.messages[0].message,
+ 'React Compiler expected error on line 3 was not triggered'
+ );
+
+ const duplicateResult = await lintFixture('duplicate-metadata.md');
+ assert.strictEqual(
+ duplicateResult.messages.length,
+ 2,
+ 'expected duplicate metadata to surface compiler diagnostic and stale metadata notice'
+ );
+ const duplicateFixed = await lintFixture('duplicate-metadata.md', {
+ fix: true,
+ });
+ assert(
+ duplicateFixed.output.includes(
+ "{expectedErrors: {'react-compiler': [4]}}"
+ ),
+ 'expected duplicates to be rewritten to a single canonical block'
+ );
+ assert(
+ !duplicateFixed.output.includes('[99]'),
+ 'expected stale line numbers to be removed from metadata'
+ );
+
+ const mixedLanguageResult = await lintFixture('mixed-language.md');
+ assert.strictEqual(
+ mixedLanguageResult.messages.length,
+ 0,
+ 'expected non-js code fences to be ignored'
+ );
+
+ const malformedResult = await lintFixture('malformed-metadata.md');
+ assert.strictEqual(
+ malformedResult.messages.length,
+ 1,
+ 'expected malformed metadata to fall back to compiler diagnostics'
+ );
+ const malformedFixed = await lintFixture('malformed-metadata.md', {
+ fix: true,
+ });
+ assert(
+ malformedFixed.output.includes(
+ "{expectedErrors: {'react-compiler': [4]}}"
+ ),
+ 'expected malformed metadata to be replaced with canonical form'
+ );
+}
+
+run().catch(error => {
+ console.error(error);
+ process.exitCode = 1;
+});
diff --git a/eslint-local-rules/index.js b/eslint-local-rules/index.js
new file mode 100644
index 000000000..1566b0ccb
--- /dev/null
+++ b/eslint-local-rules/index.js
@@ -0,0 +1,47 @@
+const lintMarkdownCodeBlocks = require('./rules/lint-markdown-code-blocks');
+
+module.exports = {
+ rules: {
+ 'lint-markdown-code-blocks': lintMarkdownCodeBlocks,
+ },
+ processors: {
+ markdown: {
+ preprocess(text) {
+ // Hack: wrap the markdown file in a dummy JS comment so ESLint feeds it
+ // through our custom rule without needing a real markdown parser here.
+ return [
+ `// Markdown content for processing\n/* ${text.replace(
+ /\*\//g,
+ '*\\/'
+ )} */`,
+ ];
+ },
+ postprocess(messages) {
+ const processedMessages = messages.flat().map((message) => {
+ if (message.suggestions) {
+ const processedSuggestions = message.suggestions.map(
+ (suggestion) => {
+ if (suggestion.fix) {
+ // Unescape */ in fix text
+ const fixedText = suggestion.fix.text.replace(
+ /\*\\\//g,
+ '*/'
+ );
+ return {
+ ...suggestion,
+ fix: {...suggestion.fix, text: fixedText},
+ };
+ }
+ return suggestion;
+ }
+ );
+ return {...message, suggestions: processedSuggestions};
+ }
+ return message;
+ });
+ return processedMessages;
+ },
+ supportsAutofix: true,
+ },
+ },
+};
diff --git a/eslint-local-rules/package.json b/eslint-local-rules/package.json
new file mode 100644
index 000000000..5fd9939a9
--- /dev/null
+++ b/eslint-local-rules/package.json
@@ -0,0 +1,9 @@
+{
+ "name": "eslint-plugin-local-rules",
+ "version": "0.0.0",
+ "main": "index.js",
+ "private": "true",
+ "scripts": {
+ "test": "node __tests__/lint-markdown-code-blocks.test.js"
+ }
+}
diff --git a/eslint-local-rules/rules/diagnostics.js b/eslint-local-rules/rules/diagnostics.js
new file mode 100644
index 000000000..886120ae8
--- /dev/null
+++ b/eslint-local-rules/rules/diagnostics.js
@@ -0,0 +1,70 @@
+function getRelativeLine(loc) {
+ return loc?.start?.line ?? loc?.line ?? 1;
+}
+
+function getRelativeColumn(loc) {
+ return loc?.start?.column ?? loc?.column ?? 0;
+}
+
+function getRelativeEndLine(loc, fallbackLine) {
+ if (loc?.end?.line != null) {
+ return loc.end.line;
+ }
+ if (loc?.line != null) {
+ return loc.line;
+ }
+ return fallbackLine;
+}
+
+function getRelativeEndColumn(loc, fallbackColumn) {
+ if (loc?.end?.column != null) {
+ return loc.end.column;
+ }
+ if (loc?.column != null) {
+ return loc.column;
+ }
+ return fallbackColumn;
+}
+
+/**
+ * @param {import('./markdown').MarkdownCodeBlock} block
+ * @param {Array<{detail: any, loc: any, message: string}>} diagnostics
+ * @returns {Array<{detail: any, message: string, relativeStartLine: number, markdownLoc: {start: {line: number, column: number}, end: {line: number, column: number}}}>}
+ */
+function normalizeDiagnostics(block, diagnostics) {
+ return diagnostics.map(({detail, loc, message}) => {
+ const relativeStartLine = Math.max(getRelativeLine(loc), 1);
+ const relativeStartColumn = Math.max(getRelativeColumn(loc), 0);
+ const relativeEndLine = Math.max(
+ getRelativeEndLine(loc, relativeStartLine),
+ relativeStartLine
+ );
+ const relativeEndColumn = Math.max(
+ getRelativeEndColumn(loc, relativeStartColumn),
+ relativeStartColumn
+ );
+
+ const markdownStartLine = block.codeStartLine + relativeStartLine - 1;
+ const markdownEndLine = block.codeStartLine + relativeEndLine - 1;
+
+ return {
+ detail,
+ message,
+ relativeStartLine,
+ markdownLoc: {
+ start: {
+ line: markdownStartLine,
+ column: relativeStartColumn,
+ },
+ end: {
+ line: markdownEndLine,
+ column: relativeEndColumn,
+ },
+ },
+ };
+ });
+}
+
+module.exports = {
+ normalizeDiagnostics,
+};
diff --git a/eslint-local-rules/rules/lint-markdown-code-blocks.js b/eslint-local-rules/rules/lint-markdown-code-blocks.js
new file mode 100644
index 000000000..a3e50c999
--- /dev/null
+++ b/eslint-local-rules/rules/lint-markdown-code-blocks.js
@@ -0,0 +1,179 @@
+const {
+ buildFenceLine,
+ getCompilerExpectedLines,
+ getSortedUniqueNumbers,
+ hasCompilerEntry,
+ metadataEquals,
+ metadataHasExpectedErrorsToken,
+ removeCompilerExpectedLines,
+ setCompilerExpectedLines,
+} = require('./metadata');
+const {normalizeDiagnostics} = require('./diagnostics');
+const {parseMarkdownFile} = require('./markdown');
+const {runReactCompiler} = require('./react-compiler');
+
+module.exports = {
+ meta: {
+ type: 'problem',
+ docs: {
+ description: 'Run React Compiler on markdown code blocks',
+ category: 'Possible Errors',
+ },
+ fixable: 'code',
+ hasSuggestions: true,
+ schema: [],
+ },
+
+ create(context) {
+ return {
+ Program(node) {
+ const filename = context.getFilename();
+ if (!filename.endsWith('.md') || !filename.includes('src/content')) {
+ return;
+ }
+
+ const sourceCode = context.getSourceCode();
+ let content = sourceCode.text;
+
+ // Extract the markdown from eslint-local-rules/index.js hack
+ const commentMatch = content.match(/\/\* ([\s\S]*) \*\/$/);
+ if (commentMatch) {
+ content = commentMatch[1].replace(/\*\\\//g, '*/');
+ }
+
+ const {blocks} = parseMarkdownFile(content, filename);
+ // For each supported code block, run the compiler and reconcile metadata.
+ for (const block of blocks) {
+ const compilerResult = runReactCompiler(
+ block.code,
+ `${filename}#codeblock`
+ );
+
+ const expectedLines = getCompilerExpectedLines(block.metadata);
+ const expectedLineSet = new Set(expectedLines);
+ const diagnostics = normalizeDiagnostics(
+ block,
+ compilerResult.diagnostics
+ );
+
+ const errorLines = new Set();
+ const unexpectedDiagnostics = [];
+
+ for (const diagnostic of diagnostics) {
+ const line = diagnostic.relativeStartLine;
+ errorLines.add(line);
+ if (!expectedLineSet.has(line)) {
+ unexpectedDiagnostics.push(diagnostic);
+ }
+ }
+
+ const normalizedErrorLines = getSortedUniqueNumbers(
+ Array.from(errorLines)
+ );
+ const missingExpectedLines = expectedLines.filter(
+ (line) => !errorLines.has(line)
+ );
+
+ const desiredMetadata = normalizedErrorLines.length
+ ? setCompilerExpectedLines(block.metadata, normalizedErrorLines)
+ : removeCompilerExpectedLines(block.metadata);
+
+ // Compute canonical metadata and attach an autofix when it differs.
+ const metadataChanged = !metadataEquals(
+ block.metadata,
+ desiredMetadata
+ );
+ const replacementLine = buildFenceLine(block.lang, desiredMetadata);
+ const replacementDiffers = block.fence.rawText !== replacementLine;
+ const applyReplacementFix = replacementDiffers
+ ? (fixer) =>
+ fixer.replaceTextRange(block.fence.range, replacementLine)
+ : null;
+
+ const hasDuplicateMetadata =
+ block.metadata.hadDuplicateExpectedErrors;
+ const hasExpectedErrorsMetadata = metadataHasExpectedErrorsToken(
+ block.metadata
+ );
+
+ const shouldFixUnexpected =
+ Boolean(applyReplacementFix) &&
+ normalizedErrorLines.length > 0 &&
+ (metadataChanged ||
+ hasDuplicateMetadata ||
+ !hasExpectedErrorsMetadata);
+
+ let fixAlreadyAttached = false;
+
+ for (const diagnostic of unexpectedDiagnostics) {
+ const reportData = {
+ node,
+ loc: diagnostic.markdownLoc,
+ message: diagnostic.message,
+ };
+
+ if (
+ shouldFixUnexpected &&
+ applyReplacementFix &&
+ !fixAlreadyAttached
+ ) {
+ reportData.fix = applyReplacementFix;
+ reportData.suggest = [
+ {
+ desc: 'Add expectedErrors metadata to suppress these errors',
+ fix: applyReplacementFix,
+ },
+ ];
+ fixAlreadyAttached = true;
+ }
+
+ context.report(reportData);
+ }
+
+ // Assert that expectedErrors is actually needed
+ if (
+ Boolean(applyReplacementFix) &&
+ missingExpectedLines.length > 0 &&
+ hasCompilerEntry(block.metadata)
+ ) {
+ const plural = missingExpectedLines.length > 1;
+ const message = plural
+ ? `React Compiler expected errors on lines ${missingExpectedLines.join(
+ ', '
+ )} were not triggered`
+ : `React Compiler expected error on line ${missingExpectedLines[0]} was not triggered`;
+
+ const reportData = {
+ node,
+ loc: {
+ start: {
+ line: block.position.start.line,
+ column: 0,
+ },
+ end: {
+ line: block.position.start.line,
+ column: block.fence.rawText.length,
+ },
+ },
+ message,
+ };
+
+ if (!fixAlreadyAttached && applyReplacementFix) {
+ reportData.fix = applyReplacementFix;
+ fixAlreadyAttached = true;
+ } else if (applyReplacementFix) {
+ reportData.suggest = [
+ {
+ desc: 'Remove stale expectedErrors metadata',
+ fix: applyReplacementFix,
+ },
+ ];
+ }
+
+ context.report(reportData);
+ }
+ }
+ },
+ };
+ },
+};
diff --git a/eslint-local-rules/rules/markdown.js b/eslint-local-rules/rules/markdown.js
new file mode 100644
index 000000000..7ca5a936f
--- /dev/null
+++ b/eslint-local-rules/rules/markdown.js
@@ -0,0 +1,100 @@
+const {parseFenceMetadata} = require('./metadata');
+
+/**
+ * @typedef {Object} MarkdownCodeBlock
+ * @property {string} code
+ * @property {number} codeStartLine
+ * @property {{start: {line: number, column: number}, end: {line: number, column: number}}} position
+ * @property {{lineIndex: number, rawText: string, metaText: string, range: [number, number]}} fence
+ * @property {string} filePath
+ * @property {string} lang
+ * @property {import('./metadata').FenceMetadata} metadata
+ */
+
+const SUPPORTED_LANGUAGES = new Set([
+ 'js',
+ 'jsx',
+ 'javascript',
+ 'ts',
+ 'tsx',
+ 'typescript',
+]);
+
+function computeLineOffsets(lines) {
+ const offsets = [];
+ let currentOffset = 0;
+
+ for (const line of lines) {
+ offsets.push(currentOffset);
+ currentOffset += line.length + 1;
+ }
+
+ return offsets;
+}
+
+function parseMarkdownFile(content, filePath) {
+ const lines = content.split('\n');
+ const lineOffsets = computeLineOffsets(lines);
+ const blocks = [];
+
+ let currentBlock = null;
+
+ for (let index = 0; index < lines.length; index++) {
+ const line = lines[index];
+ const fenceMatch = line.match(/^```(\w+)(.*)$/);
+
+ if (fenceMatch) {
+ const lang = fenceMatch[1];
+ if (!SUPPORTED_LANGUAGES.has(lang)) {
+ currentBlock = null;
+ continue;
+ }
+
+ const metaPortion = fenceMatch[2] || '';
+ const metadata = parseFenceMetadata(metaPortion);
+ currentBlock = {
+ lang,
+ metadata,
+ filePath,
+ codeLines: [],
+ codeStartLine: index + 2,
+ position: {
+ start: {line: index + 1, column: 0},
+ end: {line: index + 1, column: 0},
+ },
+ fence: {
+ lineIndex: index,
+ rawText: line,
+ metaText: metaPortion,
+ range: [lineOffsets[index] || 0, (lineOffsets[index] || 0) + line.length],
+ },
+ };
+ continue;
+ }
+
+ if (line === '```' && currentBlock) {
+ currentBlock.position.end = {line: index + 1, column: 0};
+ currentBlock.code = currentBlock.codeLines.join('\n');
+ delete currentBlock.codeLines;
+ blocks.push(currentBlock);
+ currentBlock = null;
+ continue;
+ }
+
+ if (currentBlock) {
+ currentBlock.codeLines.push(line);
+ }
+ }
+
+ return {
+ blocks,
+ lines,
+ lineOffsets,
+ };
+}
+
+module.exports = {
+ SUPPORTED_LANGUAGES,
+ computeLineOffsets,
+ parseMarkdownFile,
+};
diff --git a/eslint-local-rules/rules/metadata.js b/eslint-local-rules/rules/metadata.js
new file mode 100644
index 000000000..c86741247
--- /dev/null
+++ b/eslint-local-rules/rules/metadata.js
@@ -0,0 +1,377 @@
+/**
+ * Utilities for parsing and rewriting markdown code fence metadata.
+ *
+ * The rule keeps metadata as structured objects while editing so we only
+ * stringify at the boundary where we need to emit a replacement fence line.
+ */
+
+/**
+ * @typedef {{type: 'text', raw: string}} TextToken
+ * @typedef {{
+ * type: 'expectedErrors',
+ * entries: Record>,
+ * raw?: string,
+ * }} ExpectedErrorsToken
+ * @typedef {TextToken | ExpectedErrorsToken} MetadataToken
+ *
+ * @typedef {{
+ * leading: string,
+ * trailing: string,
+ * tokens: Array,
+ * parseError: boolean,
+ * hadDuplicateExpectedErrors: boolean,
+ * }} FenceMetadata
+ */
+
+const EXPECTED_ERRORS_BLOCK_REGEX = /\{\s*expectedErrors\s*:/;
+const REACT_COMPILER_KEY = 'react-compiler';
+
+function getSortedUniqueNumbers(values) {
+ return Array.from(new Set(values))
+ .filter((value) => typeof value === 'number' && !Number.isNaN(value))
+ .sort((a, b) => a - b);
+}
+
+function tokenizeMeta(body) {
+ if (!body) {
+ return [];
+ }
+
+ const tokens = [];
+ let current = '';
+ let depth = 0;
+
+ for (let i = 0; i < body.length; i++) {
+ const char = body[i];
+ if (char === '{') {
+ depth++;
+ } else if (char === '}') {
+ depth = Math.max(depth - 1, 0);
+ }
+
+ if (char === ' ' && depth === 0) {
+ if (current) {
+ tokens.push(current);
+ current = '';
+ }
+ continue;
+ }
+
+ current += char;
+ }
+
+ if (current) {
+ tokens.push(current);
+ }
+
+ return tokens;
+}
+
+function normalizeEntryValues(values) {
+ if (!Array.isArray(values)) {
+ return [];
+ }
+ return getSortedUniqueNumbers(values);
+}
+
+function parseExpectedErrorsEntries(rawEntries) {
+ const normalized = rawEntries
+ .replace(/([{,]\s*)([a-zA-Z_$][\w$]*)\s*:/g, '$1"$2":')
+ .replace(/'([^']*)'/g, '"$1"');
+
+ const parsed = JSON.parse(normalized);
+ const entries = {};
+
+ if (parsed && typeof parsed === 'object') {
+ for (const [key, value] of Object.entries(parsed)) {
+ entries[key] = normalizeEntryValues(Array.isArray(value) ? value.flat() : value);
+ }
+ }
+
+ return entries;
+}
+
+function parseExpectedErrorsToken(tokenText) {
+ const match = tokenText.match(/^\{\s*expectedErrors\s*:\s*(\{[\s\S]*\})\s*\}$/);
+ if (!match) {
+ return null;
+ }
+
+ const entriesSource = match[1];
+ let parseError = false;
+ let entries;
+
+ try {
+ entries = parseExpectedErrorsEntries(entriesSource);
+ } catch (error) {
+ parseError = true;
+ entries = {};
+ }
+
+ return {
+ token: {
+ type: 'expectedErrors',
+ entries,
+ raw: tokenText,
+ },
+ parseError,
+ };
+}
+
+function parseFenceMetadata(metaText) {
+ if (!metaText) {
+ return {
+ leading: '',
+ trailing: '',
+ tokens: [],
+ parseError: false,
+ hadDuplicateExpectedErrors: false,
+ };
+ }
+
+ const leading = metaText.match(/^\s*/)?.[0] ?? '';
+ const trailing = metaText.match(/\s*$/)?.[0] ?? '';
+ const bodyStart = leading.length;
+ const bodyEnd = metaText.length - trailing.length;
+ const body = metaText.slice(bodyStart, bodyEnd).trim();
+
+ if (!body) {
+ return {
+ leading,
+ trailing,
+ tokens: [],
+ parseError: false,
+ hadDuplicateExpectedErrors: false,
+ };
+ }
+
+ const tokens = [];
+ let parseError = false;
+ let sawExpectedErrors = false;
+ let hadDuplicateExpectedErrors = false;
+
+ for (const rawToken of tokenizeMeta(body)) {
+ const normalizedToken = rawToken.trim();
+ if (!normalizedToken) {
+ continue;
+ }
+
+ if (EXPECTED_ERRORS_BLOCK_REGEX.test(normalizedToken)) {
+ const parsed = parseExpectedErrorsToken(normalizedToken);
+ if (parsed) {
+ if (sawExpectedErrors) {
+ hadDuplicateExpectedErrors = true;
+ // Drop duplicates. We'll rebuild the canonical block on write.
+ continue;
+ }
+ tokens.push(parsed.token);
+ parseError = parseError || parsed.parseError;
+ sawExpectedErrors = true;
+ continue;
+ }
+ }
+
+ tokens.push({type: 'text', raw: normalizedToken});
+ }
+
+ return {
+ leading,
+ trailing,
+ tokens,
+ parseError,
+ hadDuplicateExpectedErrors,
+ };
+}
+
+function cloneMetadata(metadata) {
+ return {
+ leading: metadata.leading,
+ trailing: metadata.trailing,
+ parseError: metadata.parseError,
+ hadDuplicateExpectedErrors: metadata.hadDuplicateExpectedErrors,
+ tokens: metadata.tokens.map((token) => {
+ if (token.type === 'expectedErrors') {
+ const clonedEntries = {};
+ for (const [key, value] of Object.entries(token.entries)) {
+ clonedEntries[key] = [...value];
+ }
+ return {type: 'expectedErrors', entries: clonedEntries};
+ }
+ return {type: 'text', raw: token.raw};
+ }),
+ };
+}
+
+function findExpectedErrorsToken(metadata) {
+ return metadata.tokens.find((token) => token.type === 'expectedErrors') || null;
+}
+
+function getCompilerExpectedLines(metadata) {
+ const token = findExpectedErrorsToken(metadata);
+ if (!token) {
+ return [];
+ }
+ return getSortedUniqueNumbers(token.entries[REACT_COMPILER_KEY] || []);
+}
+
+function hasCompilerEntry(metadata) {
+ const token = findExpectedErrorsToken(metadata);
+ return Boolean(token && token.entries[REACT_COMPILER_KEY]?.length);
+}
+
+function metadataHasExpectedErrorsToken(metadata) {
+ return Boolean(findExpectedErrorsToken(metadata));
+}
+
+function stringifyExpectedErrorsToken(token) {
+ const entries = token.entries || {};
+ const keys = Object.keys(entries).filter((key) => entries[key].length > 0);
+ if (keys.length === 0) {
+ return '';
+ }
+
+ keys.sort();
+
+ const segments = keys.map((key) => {
+ const values = entries[key];
+ return `'${key}': [${values.join(', ')}]`;
+ });
+
+ return `{expectedErrors: {${segments.join(', ')}}}`;
+}
+
+function stringifyFenceMetadata(metadata) {
+ if (!metadata.tokens.length) {
+ return '';
+ }
+
+ const parts = metadata.tokens
+ .map((token) => {
+ if (token.type === 'expectedErrors') {
+ return stringifyExpectedErrorsToken(token);
+ }
+ return token.raw;
+ })
+ .filter(Boolean);
+
+ if (!parts.length) {
+ return '';
+ }
+
+ const leading = metadata.leading || ' ';
+ const trailing = metadata.trailing ? metadata.trailing.trimEnd() : '';
+ const body = parts.join(' ');
+ return `${leading}${body}${trailing}`;
+}
+
+function buildFenceLine(lang, metadata) {
+ const meta = stringifyFenceMetadata(metadata);
+ return meta ? `\`\`\`${lang}${meta}` : `\`\`\`${lang}`;
+}
+
+function metadataEquals(a, b) {
+ if (a.leading !== b.leading || a.trailing !== b.trailing) {
+ return false;
+ }
+
+ if (a.tokens.length !== b.tokens.length) {
+ return false;
+ }
+
+ for (let i = 0; i < a.tokens.length; i++) {
+ const left = a.tokens[i];
+ const right = b.tokens[i];
+ if (left.type !== right.type) {
+ return false;
+ }
+ if (left.type === 'text') {
+ if (left.raw !== right.raw) {
+ return false;
+ }
+ } else {
+ const leftKeys = Object.keys(left.entries).sort();
+ const rightKeys = Object.keys(right.entries).sort();
+ if (leftKeys.length !== rightKeys.length) {
+ return false;
+ }
+ for (let j = 0; j < leftKeys.length; j++) {
+ if (leftKeys[j] !== rightKeys[j]) {
+ return false;
+ }
+ const lValues = getSortedUniqueNumbers(left.entries[leftKeys[j]]);
+ const rValues = getSortedUniqueNumbers(right.entries[rightKeys[j]]);
+ if (lValues.length !== rValues.length) {
+ return false;
+ }
+ for (let k = 0; k < lValues.length; k++) {
+ if (lValues[k] !== rValues[k]) {
+ return false;
+ }
+ }
+ }
+ }
+ }
+
+ return true;
+}
+
+function normalizeMetadata(metadata) {
+ const normalized = cloneMetadata(metadata);
+ normalized.hadDuplicateExpectedErrors = false;
+ normalized.parseError = false;
+ if (!normalized.tokens.length) {
+ normalized.leading = '';
+ normalized.trailing = '';
+ }
+ return normalized;
+}
+
+function setCompilerExpectedLines(metadata, lines) {
+ const normalizedLines = getSortedUniqueNumbers(lines);
+ if (normalizedLines.length === 0) {
+ return removeCompilerExpectedLines(metadata);
+ }
+
+ const next = cloneMetadata(metadata);
+ let token = findExpectedErrorsToken(next);
+ if (!token) {
+ token = {type: 'expectedErrors', entries: {}};
+ next.tokens = [token, ...next.tokens];
+ }
+
+ token.entries[REACT_COMPILER_KEY] = normalizedLines;
+ return normalizeMetadata(next);
+}
+
+function removeCompilerExpectedLines(metadata) {
+ const next = cloneMetadata(metadata);
+ const token = findExpectedErrorsToken(next);
+ if (!token) {
+ return normalizeMetadata(next);
+ }
+
+ delete token.entries[REACT_COMPILER_KEY];
+
+ const hasEntries = Object.values(token.entries).some(
+ (value) => Array.isArray(value) && value.length > 0
+ );
+
+ if (!hasEntries) {
+ next.tokens = next.tokens.filter((item) => item !== token);
+ }
+
+ return normalizeMetadata(next);
+}
+
+module.exports = {
+ buildFenceLine,
+ getCompilerExpectedLines,
+ getSortedUniqueNumbers,
+ hasCompilerEntry,
+ metadataEquals,
+ metadataHasExpectedErrorsToken,
+ parseFenceMetadata,
+ removeCompilerExpectedLines,
+ setCompilerExpectedLines,
+ stringifyFenceMetadata,
+};
diff --git a/eslint-local-rules/rules/react-compiler.js b/eslint-local-rules/rules/react-compiler.js
new file mode 100644
index 000000000..1ea002f50
--- /dev/null
+++ b/eslint-local-rules/rules/react-compiler.js
@@ -0,0 +1,115 @@
+const {transformFromAstSync} = require('@babel/core');
+const {parse: babelParse} = require('@babel/parser');
+const BabelPluginReactCompiler = require('babel-plugin-react-compiler').default;
+const {
+ parsePluginOptions,
+ validateEnvironmentConfig,
+} = require('babel-plugin-react-compiler');
+
+const COMPILER_OPTIONS = {
+ noEmit: true,
+ panicThreshold: 'none',
+ environment: validateEnvironmentConfig({
+ validateRefAccessDuringRender: true,
+ validateNoSetStateInRender: true,
+ validateNoSetStateInEffects: true,
+ validateNoJSXInTryStatements: true,
+ validateNoImpureFunctionsInRender: true,
+ validateStaticComponents: true,
+ validateNoFreezingKnownMutableFunctions: true,
+ validateNoVoidUseMemo: true,
+ validateNoCapitalizedCalls: [],
+ validateHooksUsage: true,
+ validateNoDerivedComputationsInEffects: true,
+ }),
+};
+
+function hasRelevantCode(code) {
+ const functionPattern = /^(export\s+)?(default\s+)?function\s+\w+/m;
+ const arrowPattern =
+ /^(export\s+)?(const|let|var)\s+\w+\s*=\s*(\([^)]*\)|\w+)\s*=>/m;
+ const hasImports = /^import\s+/m.test(code);
+
+ return functionPattern.test(code) || arrowPattern.test(code) || hasImports;
+}
+
+function runReactCompiler(code, filename) {
+ const result = {
+ sourceCode: code,
+ events: [],
+ };
+
+ if (!hasRelevantCode(code)) {
+ return {...result, diagnostics: []};
+ }
+
+ const options = parsePluginOptions({
+ ...COMPILER_OPTIONS,
+ });
+
+ options.logger = {
+ logEvent: (_, event) => {
+ if (event.kind === 'CompileError') {
+ const category = event.detail?.category;
+ if (category === 'Todo' || category === 'Invariant') {
+ return;
+ }
+ result.events.push(event);
+ }
+ },
+ };
+
+ try {
+ const ast = babelParse(code, {
+ sourceFilename: filename,
+ sourceType: 'module',
+ plugins: ['jsx', 'typescript'],
+ });
+
+ transformFromAstSync(ast, code, {
+ filename,
+ highlightCode: false,
+ retainLines: true,
+ plugins: [[BabelPluginReactCompiler, options]],
+ sourceType: 'module',
+ configFile: false,
+ babelrc: false,
+ });
+ } catch (error) {
+ return {...result, diagnostics: []};
+ }
+
+ const diagnostics = [];
+
+ for (const event of result.events) {
+ if (event.kind !== 'CompileError') {
+ continue;
+ }
+
+ const detail = event.detail;
+ if (!detail) {
+ continue;
+ }
+
+ const loc = typeof detail.primaryLocation === 'function'
+ ? detail.primaryLocation()
+ : null;
+
+ if (loc == null || typeof loc === 'symbol') {
+ continue;
+ }
+
+ const message = typeof detail.printErrorMessage === 'function'
+ ? detail.printErrorMessage(result.sourceCode, {eslint: true})
+ : detail.description || 'Unknown React Compiler error';
+
+ diagnostics.push({detail, loc, message});
+ }
+
+ return {...result, diagnostics};
+}
+
+module.exports = {
+ hasRelevantCode,
+ runReactCompiler,
+};
diff --git a/package.json b/package.json
index 61d6cd5e4..2367a98f0 100644
--- a/package.json
+++ b/package.json
@@ -7,8 +7,8 @@
"analyze": "ANALYZE=true next build",
"dev": "next-remote-watch ./src/content",
"build": "next build && node --experimental-modules ./scripts/downloadFonts.mjs",
- "lint": "next lint",
- "lint:fix": "next lint --fix",
+ "lint": "next lint && eslint \"src/content/**/*.md\"",
+ "lint:fix": "next lint --fix && eslint \"src/content/**/*.md\" --fix",
"format:source": "prettier --config .prettierrc --write \"{plugins,src}/**/*.{js,ts,jsx,tsx,css}\"",
"nit:source": "prettier --config .prettierrc --list-different \"{plugins,src}/**/*.{js,ts,jsx,tsx,css}\"",
"prettier": "yarn format:source",
@@ -21,7 +21,8 @@
"postinstall": "is-ci || husky install .husky",
"check-all": "npm-run-all prettier lint:fix tsc rss",
"rss": "node scripts/generateRss.js",
- "deadlinks": "node scripts/deadLinkChecker.js"
+ "deadlinks": "node scripts/deadLinkChecker.js",
+ "test:eslint-local-rules": "yarn --cwd eslint-local-rules test"
},
"dependencies": {
"@codesandbox/sandpack-react": "2.13.5",
@@ -69,6 +70,7 @@
"eslint-plugin-flowtype": "4.x",
"eslint-plugin-import": "2.x",
"eslint-plugin-jsx-a11y": "6.x",
+ "eslint-plugin-local-rules": "link:eslint-local-rules",
"eslint-plugin-react": "7.x",
"eslint-plugin-react-compiler": "^19.0.0-beta-e552027-20250112",
"eslint-plugin-react-hooks": "^0.0.0-experimental-fabef7a6b-20221215",
diff --git a/yarn.lock b/yarn.lock
index cc7843bb8..b8480f1c5 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -3405,6 +3405,10 @@ eslint-plugin-jsx-a11y@^6.4.1:
safe-regex-test "^1.0.3"
string.prototype.includes "^2.0.0"
+"eslint-plugin-local-rules@link:eslint-local-rules":
+ version "0.0.0"
+ uid ""
+
eslint-plugin-react-compiler@^19.0.0-beta-e552027-20250112:
version "19.0.0-beta-e552027-20250112"
resolved "https://registry.yarnpkg.com/eslint-plugin-react-compiler/-/eslint-plugin-react-compiler-19.0.0-beta-e552027-20250112.tgz#f4ad9cebe47615ebf6097a8084a30d761ee164f4"