From 328bf5f6910151332974e5ae4c2c492e17a39843 Mon Sep 17 00:00:00 2001
From: Andrew Nicols <andrew@nicols.co.uk>
Date: Fri, 13 Oct 2023 14:50:58 +0800
Subject: [PATCH] MDL-79697 core: PSR-4 NS can be spread across multiple dirs

The PSR-4 specification does not preclude a single namespaces from
having multiple sources. This is the case for several PSR standards
including standard packagist packages distributed by PSR:

- PSR-7 - HTTP Message Interfaces: \Psr\Http\Message
- PSR-17 - HTTP Factories: \Psr\Http\Message
- PSR-15 - http-server-handler: \Psr\Http\Server
- PSR-15 - http-server-middleware: \Psr\Http\Server
---
 lib/classes/component.php    | 26 +++++++++++++++++---------
 lib/tests/component_test.php | 25 ++++++++++++++++++++++++-
 2 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/lib/classes/component.php b/lib/classes/component.php
index b9ba8a82a31..d09361afa59 100644
--- a/lib/classes/component.php
+++ b/lib/classes/component.php
@@ -90,8 +90,8 @@ class core_component {
         'Mustache' => 'lib/mustache/src/Mustache',
         'CFPropertyList' => 'lib/plist/classes/CFPropertyList',
     );
-    /** @var array associative array of PRS-4 namespaces and corresponding paths. */
-    protected static $psr4namespaces = array(
+    /** @var array<string|array<string>> associative array of PRS-4 namespaces and corresponding paths. */
+    protected static $psr4namespaces = [
         'MaxMind' => 'lib/maxmind/MaxMind',
         'GeoIp2' => 'lib/maxmind/GeoIp2',
         'Sabberworm\\CSS' => 'lib/php-css-parser',
@@ -110,13 +110,16 @@ class core_component {
         'MyCLabs\\Enum' => 'lib/php-enum/src',
         'PhpXmlRpc' => 'lib/phpxmlrpc',
         'Psr\\Http\\Client' => 'lib/psr/http-client/src',
-        'Psr\\Http\\Factory' => 'lib/psr/http-factory/src',
-        'Psr\\Http\\Message' => 'lib/psr/http-message/src',
+        'Psr\\Http\\Message' => [
+            'lib/psr/http-message/src',
+            'lib/psr/http-factory/src',
+        ],
+        'Psr\\EventDispatcher' => 'lib/psr/event-dispatcher/src',
         'GuzzleHttp\\Psr7' => 'lib/guzzlehttp/psr7/src',
         'GuzzleHttp\\Promise' => 'lib/guzzlehttp/promises/src',
         'GuzzleHttp' => 'lib/guzzlehttp/guzzle/src',
         'Kevinrob\\GuzzleCache' => 'lib/guzzlehttp/kevinrob/guzzlecache/src',
-    );
+    ];
 
     /**
      * Class loader for Frankenstyle named classes in standard locations.
@@ -175,10 +178,15 @@ class core_component {
      */
     protected static function psr_classloader($class) {
         // Iterate through each PSR-4 namespace prefix.
-        foreach (self::$psr4namespaces as $prefix => $path) {
-            $file = self::get_class_file($class, $prefix, $path, array('\\'));
-            if (!empty($file) && file_exists($file)) {
-                return $file;
+        foreach (self::$psr4namespaces as $prefix => $paths) {
+            if (!is_array($paths)) {
+                $paths = [$paths];
+            }
+            foreach ($paths as $path) {
+                $file = self::get_class_file($class, $prefix, $path, ['\\']);
+                if (!empty($file) && file_exists($file)) {
+                    return $file;
+                }
             }
         }
 
diff --git a/lib/tests/component_test.php b/lib/tests/component_test.php
index 91693c3e8c0..22f68d2a032 100644
--- a/lib/tests/component_test.php
+++ b/lib/tests/component_test.php
@@ -631,7 +631,8 @@ class component_test extends advanced_testcase {
         // This is not in the spec, but may come up in some libraries using both namespaces and PEAR-style class names.
         // If problems arise we can remove this test, but will need to add a warning.
         // Normalise to forward slash for testing purposes.
-        $directory = str_replace('\\', '/', $CFG->dirroot) . "/lib/tests/fixtures/component/";
+        $dirroot = str_replace('\\', '/', $CFG->dirroot);
+        $directory = "{$dirroot}/lib/tests/fixtures/component/";
 
         $psr0 = [
           'psr0'      => 'lib/tests/fixtures/component/psr0',
@@ -702,6 +703,28 @@ class component_test extends advanced_testcase {
               'classname' => 'overlap_subnamespace_example2',
               'file' => "{$directory}overlap/subnamespace/example2.php",
           ],
+            'PSR-4 namespaces can come from multiple sources - first source' => [
+                'psr0' => $psr0,
+                'psr4' => [
+                    'Psr\\Http\\Message' => [
+                        'lib/psr/http-message/src',
+                        'lib/psr/http-factory/src',
+                    ],
+                ],
+                'classname' => 'Psr\Http\Message\ServerRequestInterface',
+                'includedfiles' => "{$dirroot}/lib/psr/http-message/src/ServerRequestInterface.php",
+            ],
+            'PSR-4 namespaces can come from multiple sources - second source' => [
+                'psr0' => [],
+                'psr4' => [
+                    'Psr\\Http\\Message' => [
+                        'lib/psr/http-message/src',
+                        'lib/psr/http-factory/src',
+                    ],
+                ],
+                'classname' => 'Psr\Http\Message\ServerRequestFactoryInterface',
+                'includedfiles' => "{$dirroot}/lib/psr/http-factory/src/ServerRequestFactoryInterface.php",
+            ],
         ];
     }