Issue #3156651 by alexpott, dww, pfrenssen, Kristen Pol, xjm, andypost, Gábor Hojtsy, bradjones1: Prevent Drupal 8.9 and 9.0 from being installed on PHP 8

composer.lock

@@ -671,7 +671,7 @@
             "dist": {
                 "type": "path",
                 "url": "core",
-                "reference": "00a84fa61ee921f106f7912c3ca0393a2c328e68"
+                "reference": "9e58f98953ff193220b4366d62446dc984f346d4"
             },
             "require": {
                 "asm89/stack-cors": "^1.1",
@@ -698,7 +698,7 @@
                 "laminas/laminas-feed": "^2.12",
                 "masterminds/html5": "^2.1",
                 "pear/archive_tar": "^1.4.9",
-                "php": ">=7.0.8",
+                "php": "^7.0.8",
                 "psr/log": "^1.0",
                 "stack/builder": "^1.0",
                 "symfony-cmf/routing": "^1.4",

core/composer.json

@@ -17,7 +17,7 @@
         "ext-SPL": "*",
         "ext-tokenizer": "*",
         "ext-xml": "*",
-        "php": ">=7.0.8",
+        "php": "^7.0.8",
         "symfony/class-loader": "~3.4.0",
         "symfony/console": "~3.4.0",
         "symfony/dependency-injection": "~3.4.26",

core/install.php

@@ -29,6 +29,10 @@ if (version_compare(PHP_VERSION, '7.0.8') < 0) {
   print 'Your PHP installation is too old. Drupal requires at least PHP 7.0.8. See the <a href="https://www.drupal.org/requirements">system requirements</a> page for more information.';
   exit;
 }
+elseif (version_compare(PHP_VERSION, '8.0', '>=')) {
+  print 'Update to the latest release of Drupal 9 for improved PHP 8 support, or use PHP 7.4. See the <a href="https://www.drupal.org/requirements">system requirements</a> page for more information.';
+  exit;
+}
 
 // Initialize the autoloader.
 $class_loader = require_once $root_path . '/autoload.php';