Class: Shakapacker::SwcMigrator

Inherits:
Object
  • Object
show all
Defined in:
lib/shakapacker/swc_migrator.rb

Constant Summary collapse

BABEL_PACKAGES =

Babel packages safe to remove when migrating to SWC Note: @babel/core and @babel/eslint-parser are excluded as they may be needed for ESLint

[
  "@babel/plugin-proposal-class-properties",
  "@babel/plugin-proposal-object-rest-spread",
  "@babel/plugin-syntax-dynamic-import",
  "@babel/plugin-transform-destructuring",
  "@babel/plugin-transform-regenerator",
  "@babel/plugin-transform-runtime",
  "@babel/preset-env",
  "@babel/preset-react",
  "@babel/preset-typescript",
  "@babel/runtime",
  "babel-loader",
  "babel-plugin-macros",
  "babel-plugin-transform-react-remove-prop-types"
].freeze
ESLINT_BABEL_PACKAGES =

Babel packages that may be needed for ESLint - only remove if user explicitly confirms

[
  "@babel/core",
  "@babel/eslint-parser"
].freeze
SWC_PACKAGES = 
{
  "@swc/core" => "^1.7.39",
  "swc-loader" => "^0.2.6"
}.freeze
ESLINT_CONFIG_FILES = 
%w[
  .eslintrc
  .eslintrc.js
  .eslintrc.cjs
  .eslintrc.yaml
  .eslintrc.yml
  .eslintrc.json
].freeze
SWC_CONFIG_WEBPACK_HEADER = 
<<~JS.freeze
  // config/swc.config.js
  // This file is merged with Shakapacker's default SWC configuration
  // See: https://swc.rs/docs/configuration/compilation
JS
SWC_CONFIG_RSPACK_HEADER =

Rspack never reads config/swc.config.js: package/rules/rspack.ts sets its builtin:swc-loader options inline, so the file is generated with a header that says so.

The example keeps test: 'match' and overrides the JS and TS rules separately on purpose. Matching on use.loader alone (a single override with no test) looks tidier but is wrong: webpack-merge cannot pair such an override with a specific rule, so it appends builtin:swc-loader onto EVERY rule's use chain, including the CSS and Sass rules. Verified at webpack-merge 5.10.0 and 6.0.1.

<<~JS.freeze
  // config/swc.config.js
  // NOTE: This file is NOT read when assets_bundler is 'rspack'.
  // Shakapacker's Rspack config sets its 'builtin:swc-loader' options inline, so nothing
  // here reaches your build. To customize SWC for Rspack, apply webpack-merge's
  // mergeWithRules to the OUTPUT of generateRspackConfig(). Passing an override into
  // generateRspackConfig() cannot replace the built-in rule: it merges with plain merge,
  // which concatenates module.rules and leaves the built-in rule in place alongside yours.
  //
  // Use options: 'merge', not 'replace'. 'merge' deep-merges into the built-in options so
  // parser.jsx (JS), parser.syntax/tsx (TS), and transform.react.runtime survive.
  // 'replace' swaps the whole options object and silently drops them, breaking JSX and
  // TypeScript compilation.
  //
  // Keep test: 'match' in the merge spec. Matching on use.loader alone appends
  // builtin:swc-loader to every rule's use chain, CSS and Sass included.
  //
  //   const { mergeWithRules } = require('shakapacker');
  //   const { generateRspackConfig } = require('shakapacker/rspack');
  //
  //   const swcOptions = { jsc: { keepClassNames: true } }; // your SWC options
  //
  //   module.exports = mergeWithRules({
  //     module: { rules: { test: 'match', use: { loader: 'match', options: 'merge' } } },
  //   })(generateRspackConfig(), {
  //     module: {
  //       rules: [
  //         // Shakapacker registers separate builtin:swc-loader rules for JS and TS.
  //         // Override both: a JS-only override never reaches .ts/.tsx files.
  //         {
  //           test: /\\.(js|jsx|mjs)$/,
  //           use: [{ loader: 'builtin:swc-loader', options: swcOptions }],
  //         },
  //         {
  //           test: /\\.(ts|tsx)$/,
  //           use: [{ loader: 'builtin:swc-loader', options: swcOptions }],
  //         },
  //       ],
  //     },
  //   });
  //
  // See: https://github.com/shakacode/shakapacker/blob/main/docs/rspack.md
JS
SWC_CONFIG_BODY = 
<<~JS.freeze
  const { env } = require('shakapacker');

  module.exports = {
    options: {
      jsc: {
        // CRITICAL for Stimulus compatibility: Prevents SWC from mangling class names
        // which breaks Stimulus's class-based controller discovery mechanism
        keepClassNames: true,
        transform: {
          react: {
            runtime: 'automatic',
            refresh: env.isDevelopment && env.runningWebpackDevServer,
          },
        },
      },
    },
  };
JS
DEFAULT_SWC_CONFIG =

Kept for backward compatibility: same value as before, and still the webpack variant.

"#{SWC_CONFIG_WEBPACK_HEADER}\n#{SWC_CONFIG_BODY}".freeze
RSPACK_SWC_CONFIG = 
"#{SWC_CONFIG_RSPACK_HEADER}\n#{SWC_CONFIG_BODY}".freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(root_path, logger: nil) ⇒ SwcMigrator

Returns a new instance of SwcMigrator.



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# File 'lib/shakapacker/swc_migrator.rb', line 132

def initialize(root_path, logger: nil)
  @root_path = Pathname.new(root_path)
  @logger = logger || Logger.new($stdout)
end

Instance Attribute Details

#logger ⇒ Object (readonly)

Returns the value of attribute logger.



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# File 'lib/shakapacker/swc_migrator.rb', line 9

def logger
  @logger
end

#root_path ⇒ Object (readonly)

Returns the value of attribute root_path.



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# File 'lib/shakapacker/swc_migrator.rb', line 9

def root_path
  @root_path
end

Instance Method Details

#clean_babel_packages(run_installer: true) ⇒ Object 



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# File 'lib/shakapacker/swc_migrator.rb', line 175

def clean_babel_packages(run_installer: true)
  logger.info "🧹 Removing Babel packages..."

  package_json_path = root_path.join("package.json")
  unless package_json_path.exist?
    logger.error "❌ No package.json found"
    return { removed_packages: [], config_files_deleted: [], preserved_packages: [] }
  end

  # Check if ESLint uses Babel parser
  preserved_for_eslint = []
  if eslint_uses_babel?
    logger.info "\n⚠️  ESLint configuration detected that uses Babel parser"
    logger.info "   Preserving @babel/core and @babel/eslint-parser for ESLint compatibility"
    logger.info "   To switch ESLint parser:"
    logger.info "   1. For TypeScript: use @typescript-eslint/parser"
    logger.info "   2. For JavaScript: use espree (ESLint's default parser)"
    preserved_for_eslint = ESLINT_BABEL_PACKAGES
  end

  removed_packages = remove_babel_from_package_json(package_json_path, preserve: preserved_for_eslint)
  deleted_files = delete_babel_config_files

  if removed_packages.any?
    logger.info "✅ Babel packages removed successfully!"
    run_package_manager_install if run_installer
  else
    logger.info "ℹ️  No Babel packages found to remove"
  end

  { removed_packages: removed_packages, config_files_deleted: deleted_files, preserved_packages: preserved_for_eslint }
end

#find_babel_packages ⇒ Object 



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# File 'lib/shakapacker/swc_migrator.rb', line 208

def find_babel_packages
  package_json_path = root_path.join("package.json")
  return [] unless package_json_path.exist?

  begin
    package_json = JSON.parse(File.read(package_json_path))
    dependencies = package_json["dependencies"] || {}
    dev_dependencies = package_json["devDependencies"] || {}
    all_deps = dependencies.merge(dev_dependencies)

    # Find all babel packages (including ESLint-related ones for display)
    all_babel_packages = BABEL_PACKAGES + ESLINT_BABEL_PACKAGES
    found_packages = all_babel_packages.select { |pkg| all_deps.key?(pkg) }
    found_packages
  rescue JSON::ParserError => e
    logger.error "Failed to parse package.json: #{e.message}"
    []
  end
end

#migrate_to_swc(run_installer: true) ⇒ Object 



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# File 'lib/shakapacker/swc_migrator.rb', line 137

def migrate_to_swc(run_installer: true)
  logger.info "🔄 Starting migration from Babel to SWC..."

  results = {
    config_updated: update_shakapacker_config,
    packages_installed: install_swc_packages,
    swc_config_created: create_swc_config,
    babel_packages_found: find_babel_packages
  }

  logger.info "🎉 Migration to SWC complete!"
  logger.info "   Note: SWC is approximately 20x faster than Babel for transpilation."
  logger.info "   Please test your application thoroughly after migration."
  logger.info "\n📝 Configuration Info:"
  log_swc_config_guidance

  # Show cleanup recommendations if babel packages found
  if results[:babel_packages_found].any?
    logger.info "\n🧹 Cleanup Recommendations:"
    logger.info "   Found the following Babel packages in your package.json:"
    results[:babel_packages_found].each do |package|
      logger.info "   - #{package}"
    end
    logger.info "\n   To remove them, run:"
    logger.info "   bundle exec rake shakapacker:clean_babel_packages"
  end

  # Suggest running doctor to verify configuration
  logger.info "\n🩺 Run 'bundle exec rake shakapacker:doctor' to verify your configuration"

  # Run package manager install if packages were added
  if run_installer && results[:packages_installed].any?
    run_package_manager_install
  end

  results
end