Adds a version check when using --use-pnp

Author: Maël Nison

packages/create-react-app/createReactApp.js

@@ -242,7 +242,22 @@ function createApp(name, verbose, version, useNpm, usePnp, template) {
  // Fall back to latest supported react-scripts for npm 3
  version = 'react-scripts@0.9.x';
  }
+ } else if (usePnp) {
+ const yarnInfo = checkYarnVersion();
+ if (!yarnInfo.hasMinYarnPnp) {
+ if (yarnInfo.yarnVersion) {
+ chalk.yellow(
+ `You are using Yarn ${
+ yarnInfo.yarnVersion
+ } together with the --use-pnp flag, but Plug'n'Play is only supported starting from the 1.12 release.\n\n` +
+ `Please update to Yarn 1.12 or higher for a better, fully supported experience.\n`
+ );
+ }
+ // 1.11 had an issue with webpack-dev-middleware, so better not use PnP with it (never reached stable, but still)
+ usePnp = false;
+ }
  }
+
  run(
  root,
  appName,
@@ -565,6 +580,23 @@ function checkNpmVersion() {
  };
 }
 
+function checkYarnVersion() {
+ let hasMinYarnPnp = false;
+ let yarnVersion = null;
+ try {
+ yarnVersion = execSync('yarnpkg --version')
+ .toString()
+ .trim();
+ hasMinYarnPnp = semver.gte(yarnVersion, '1.12.0');
+ } catch (err) {
+ // ignore
+ }
+ return {
+ hasMinYarnPnp: hasMinYarnPnp,
+ yarnVersion: yarnVersion,
+ };
+}
+
 function checkNodeVersion(packageName) {
  const packageJsonPath = path.resolve(
  process.cwd(),