Needed a config plugin to compile for latest expo

[jonahallibone]

I had to write this plugin:

// Expo config plugin to:
// - Conditionally add iOS entitlements for extended VA and increased memory
// - Force C++20 for all Pods to satisfy RN 0.81 bridging headers

const {
  withDangerousMod,
  withXcodeProject,
  createRunOncePlugin,
} = require('@expo/config-plugins');
const fs = require('fs');
const path = require('path');

const PLUGIN_NAME = 'llama-rn-plugin';
const PLUGIN_VERSION = '1.0.0';

/**
 * @typedef {Object} PluginOptions
 * @property {boolean} [enableEntitlements=true] Enable adding iOS entitlements
 * @property {string}  [entitlementsProfile='production'] EAS build profile name to enable entitlements for
 * @property {boolean} [forceCxx20=true] Force C++20 for all Pods targets
 */

/** @type {import('@expo/config-plugins').ConfigPlugin<PluginOptions>} */
function withLlamaRn(config, options = {}) {
  const {
    enableEntitlements = true,
    entitlementsProfile = 'production',
    forceCxx20 = true,
  } = options;

  // 1) Conditionally add iOS entitlements
  const isProdProfile =
    process.env.EAS_BUILD_PROFILE === entitlementsProfile ||
    process.env.NODE_ENV === 'production';

  if (enableEntitlements && isProdProfile) {
    config.ios = config.ios || {};
    config.ios.entitlements = config.ios.entitlements || {};
    config.ios.entitlements[
      'com.apple.developer.kernel.extended-virtual-addressing'
    ] = true;
    config.ios.entitlements[
      'com.apple.developer.kernel.increased-memory-limit'
    ] = true;
  }

  // 2) Enforce C++20 for app target and all Pods
  if (forceCxx20) {
    // 2a) App target via Xcode project settings
    config = withXcodeProject(config, (c) => {
      const project = c.modResults;
      const configs = project.pbxXCBuildConfigurationSection();
      for (const key in configs) {
        const cfg = configs[key];
        if (typeof cfg !== 'object' || !cfg.buildSettings) continue;
        cfg.buildSettings['CLANG_CXX_LANGUAGE_STANDARD'] = '"gnu++20"';
        cfg.buildSettings['CLANG_CXX_LIBRARY'] = '"libc++"';
        // Use a single string to avoid pbxproj array formatting issues
        const current = String(
          cfg.buildSettings['OTHER_CPLUSPLUSFLAGS'] || '$(inherited)',
        );
        if (!current.includes('-std=gnu++20')) {
          cfg.buildSettings['OTHER_CPLUSPLUSFLAGS'] =
            '"$(inherited) -std=gnu++20"';
        } else if (!current.startsWith('"')) {
          cfg.buildSettings['OTHER_CPLUSPLUSFLAGS'] = `"${current}"`;
        }
      }
      return c;
    });

    // 2b) Pods targets via Podfile post_install
    config = withDangerousMod(config, [
      'ios',
      async (c) => {
        const podfilePath = path.join(
          c.modRequest.projectRoot,
          'ios',
          'Podfile',
        );
        if (!fs.existsSync(podfilePath)) return c;
        let contents = fs.readFileSync(podfilePath, 'utf8');

        if (contents.includes('LLAMA_RN_CXX20')) return c;

        const postInstallIdx = contents.indexOf('post_install do |installer|');
        if (postInstallIdx === -1) return c;

        // Insert just before the end of the post_install block
        // Find the closing "\n  end" that ends the post_install block after its start index
        const endIdx = contents.indexOf('\n  end', postInstallIdx);
        if (endIdx === -1) return c;

        const insert = `\n    # LLAMA_RN_CXX20: Force C++20 on all Pods\n    installer.pods_project.targets.each do |target|\n      target.build_configurations.each do |config|\n        config.build_settings['CLANG_CXX_LANGUAGE_STANDARD'] = 'gnu++20'\n        config.build_settings['CLANG_CXX_LIBRARY'] = 'libc++'\n        config.build_settings['OTHER_CPLUSPLUSFLAGS'] = '$(inherited) -std=gnu++20'\n      end\n    end\n`;

        const updated =
          contents.slice(0, endIdx) + insert + contents.slice(endIdx);
        fs.writeFileSync(podfilePath, updated);
        return c;
      },
    ]);
  }

  return config;
}

module.exports = createRunOncePlugin(withLlamaRn, PLUGIN_NAME, PLUGIN_VERSION);

to get this working with the latest expo version. Is this unnecessary or is there a simpler solution?

[jhen0409]

Yeah it maybe needed.

Since I haven't use Expo for internally or personally, so I don't know if it will install correctly. But I can accept any PR for Expo support.