modern-module-resolution.ts

// Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the MIT license.
// See LICENSE in the project root for license information.

// This is a workaround for https://github.com/eslint/eslint/issues/3458
//
// To correct how ESLint searches for plugin packages, add this line to the top of your project's .eslintrc.js file:
//
//    require("@rushstack/eslint-patch/modern-module-resolution");
//
const path = require('path');
const fs = require('fs');

const isModuleResolutionError: (ex: unknown) => boolean = (ex) =>
  typeof ex === 'object' && !!ex && 'code' in ex && (ex as { code: unknown }).code === 'MODULE_NOT_FOUND';

// Module path for eslintrc.cjs
// Example: ".../@eslint/eslintrc/dist/eslintrc.cjs"
let eslintrcBundlePath: string | undefined = undefined;

// Module path for config-array-factory.js
// Example: ".../@eslint/eslintrc/lib/config-array-factory"
let configArrayFactoryPath: string | undefined = undefined;

// Module path for relative-module-resolver.js
// Example: ".../@eslint/eslintrc/lib/shared/relative-module-resolver"
let moduleResolverPath: string | undefined = undefined;

// Folder path where ESLint's package.json can be found
// Example: ".../node_modules/eslint"
let eslintFolder: string | undefined = undefined;

// Probe for the ESLint >=8.0.0 layout:
for (let currentModule = module; ; ) {
  if (!eslintrcBundlePath) {
    // For ESLint >=8.0.0, all @eslint/eslintrc code is bundled at this path:
    //   .../@eslint/eslintrc/dist/eslintrc.cjs
    try {
      const eslintrcFolder = path.dirname(
        require.resolve('@eslint/eslintrc/package.json', { paths: [currentModule.path] })
      );

      // Make sure we actually resolved the module in our call path
      // and not some other spurious dependency.
      if (path.join(eslintrcFolder, 'dist/eslintrc.cjs') === currentModule.filename) {
        eslintrcBundlePath = path.join(eslintrcFolder, 'dist/eslintrc.cjs');
      }
    } catch (ex: unknown) {
      // Module resolution failures are expected, as we're walking
      // up our require stack to look for eslint. All other errors
      // are rethrown.
      if (!isModuleResolutionError(ex)) {
        throw ex;
      }
    }
  } else {
    // Next look for a file in ESLint's folder
    //   .../eslint/lib/cli-engine/cli-engine.js
    try {
      const eslintCandidateFolder = path.dirname(
        require.resolve('eslint/package.json', {
          paths: [currentModule.path]
        })
      );

      // Make sure we actually resolved the module in our call path
      // and not some other spurious dependency.
      if (path.join(eslintCandidateFolder, 'lib/cli-engine/cli-engine.js') === currentModule.filename) {
        eslintFolder = eslintCandidateFolder;
        break;
      }
    } catch (ex: unknown) {
      // Module resolution failures are expected, as we're walking
      // up our require stack to look for eslint. All other errors
      // are rethrown.
      if (!isModuleResolutionError(ex)) {
        throw ex;
      }
    }
  }

  if (!currentModule.parent) {
    break;
  }
  currentModule = currentModule.parent;
}

if (!eslintFolder) {
  // Probe for the ESLint >=7.8.0 layout:
  for (let currentModule = module; ; ) {
    if (!configArrayFactoryPath) {
      // For ESLint >=7.8.0, config-array-factory.js is at this path:
      //   .../@eslint/eslintrc/lib/config-array-factory.js
      try {
        const eslintrcFolder = path.dirname(
          require.resolve('@eslint/eslintrc/package.json', {
            paths: [currentModule.path]
          })
        );

        if (path.join(eslintrcFolder, '/lib/config-array-factory.js') == currentModule.filename) {
          configArrayFactoryPath = path.join(eslintrcFolder, 'lib/config-array-factory.js');
          moduleResolverPath = path.join(eslintrcFolder, 'lib/shared/relative-module-resolver');
        }
      } catch (ex: unknown) {
        // Module resolution failures are expected, as we're walking
        // up our require stack to look for eslint. All other errors
        // are rethrown.
        if (!isModuleResolutionError(ex)) {
          throw ex;
        }
      }
    } else {
      // Next look for a file in ESLint's folder
      //   .../eslint/lib/cli-engine/cli-engine.js
      try {
        const eslintCandidateFolder = path.dirname(
          require.resolve('eslint/package.json', {
            paths: [currentModule.path]
          })
        );

        if (path.join(eslintCandidateFolder, 'lib/cli-engine/cli-engine.js') == currentModule.filename) {
          eslintFolder = eslintCandidateFolder;
          break;
        }
      } catch (ex: unknown) {
        // Module resolution failures are expected, as we're walking
        // up our require stack to look for eslint. All other errors
        // are rethrown.
        if (!isModuleResolutionError(ex)) {
          throw ex;
        }
      }
    }

    if (!currentModule.parent) {
      break;
    }
    currentModule = currentModule.parent;
  }
}

if (!eslintFolder) {
  // Probe for the <7.8.0 layout:
  for (let currentModule = module; ; ) {
    // For ESLint <7.8.0, config-array-factory.js was at this path:
    //   .../eslint/lib/cli-engine/config-array-factory.js
    if (/[\\/]eslint[\\/]lib[\\/]cli-engine[\\/]config-array-factory\.js$/i.test(currentModule.filename)) {
      eslintFolder = path.join(path.dirname(currentModule.filename), '../..');
      configArrayFactoryPath = path.join(eslintFolder, 'lib/cli-engine/config-array-factory');
      moduleResolverPath = path.join(eslintFolder, 'lib/shared/relative-module-resolver');
      break;
    }

    if (!currentModule.parent) {
      // This was tested with ESLint 6.1.0 .. 7.12.1.
      throw new Error(
        'Failed to patch ESLint because the calling module was not recognized.\n' +
          'If you are using a newer ESLint version that may be unsupported, please create a GitHub issue:\n' +
          'https://github.com/microsoft/rushstack/issues'
      );
    }
    currentModule = currentModule.parent;
  }
}

// Detect the ESLint package version
const eslintPackageJson = fs.readFileSync(path.join(eslintFolder, 'package.json')).toString();
const eslintPackageObject = JSON.parse(eslintPackageJson);
const eslintPackageVersion = eslintPackageObject.version;
const versionMatch = /^([0-9]+)\./.exec(eslintPackageVersion); // parse the SemVer MAJOR part
if (!versionMatch) {
  throw new Error('Unable to parse ESLint version: ' + eslintPackageVersion);
}
const eslintMajorVersion = Number(versionMatch[1]);
if (!(eslintMajorVersion >= 6 && eslintMajorVersion <= 8)) {
  throw new Error(
    'The patch-eslint.js script has only been tested with ESLint version 6.x, 7.x, and 8.x.' +
      ` (Your version: ${eslintPackageVersion})\n` +
      'Consider reporting a GitHub issue:\n' +
      'https://github.com/microsoft/rushstack/issues'
  );
}

let ConfigArrayFactory;
if (eslintMajorVersion === 8) {
  ConfigArrayFactory = require(eslintrcBundlePath!).Legacy.ConfigArrayFactory;
} else {
  ConfigArrayFactory = require(configArrayFactoryPath!).ConfigArrayFactory;
}
if (!ConfigArrayFactory.__patched) {
  ConfigArrayFactory.__patched = true;

  let ModuleResolver: { resolve: any };
  if (eslintMajorVersion === 8) {
    ModuleResolver = require(eslintrcBundlePath!).Legacy.ModuleResolver;
  } else {
    ModuleResolver = require(moduleResolverPath!);
  }
  const originalLoadPlugin = ConfigArrayFactory.prototype._loadPlugin;

  if (eslintMajorVersion === 6) {
    // ESLint 6.x
    ConfigArrayFactory.prototype._loadPlugin = function (
      name: string,
      importerPath: string,
      importerName: string
    ) {
      const originalResolve = ModuleResolver.resolve;
      try {
        ModuleResolver.resolve = function (moduleName: string, relativeToPath: string) {
          // resolve using importerPath instead of relativeToPath
          return originalResolve.call(this, moduleName, importerPath);
        };
        return originalLoadPlugin.apply(this, arguments);
      } finally {
        ModuleResolver.resolve = originalResolve;
      }
    };
  } else {
    // ESLint 7.x || 8.x
    ConfigArrayFactory.prototype._loadPlugin = function (name: string, ctx: Record<string, unknown>) {
      const originalResolve = ModuleResolver.resolve;
      try {
        ModuleResolver.resolve = function (moduleName: string, relativeToPath: string) {
          // resolve using ctx.filePath instead of relativeToPath
          return originalResolve.call(this, moduleName, ctx.filePath);
        };
        return originalLoadPlugin.apply(this, arguments);
      } finally {
        ModuleResolver.resolve = originalResolve;
      }
    };
  }
}