Allow plugins to use PSR-4 namespace mapping (#4188)

* Allow plugins to use PSR-4 namespace mapping
this is a reduced implementation which serves the 99% use case without being horribly breakable.

Plugins may now specify a `src-namespace-prefix`, which should be set to the namespace of the classes in `src`.
If the old system is used, `src-namespace-prefix` can be omitted, or set to an empty string.

Examples:
- If `src-namespace-prefix` is `dktapps\test`, `dktapps\test\Main` will be searched for in `src/Main.php`, instead of `src/dktapps/test/Main.php`.

* Migrate TesterPlugin to PSR-4

composer.lock

@@ -415,12 +415,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/pmmp/ClassLoader.git",
-                "reference": "c0133050639cd4a8baefc56a4f334f269c66a7e0"
+                "reference": "9fb3957cbfe5b37dae8952e072b35540fb4d9aa7"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/pmmp/ClassLoader/zipball/c0133050639cd4a8baefc56a4f334f269c66a7e0",
+                "url": "https://api.github.com/repos/pmmp/ClassLoader/zipball/9fb3957cbfe5b37dae8952e072b35540fb4d9aa7",
-                "reference": "c0133050639cd4a8baefc56a4f334f269c66a7e0",
+                "reference": "9fb3957cbfe5b37dae8952e072b35540fb4d9aa7",
                 "shasum": ""
             },
             "require": {
@@ -433,7 +433,7 @@
             },
             "require-dev": {
                 "phpstan/extension-installer": "^1.0",
-                "phpstan/phpstan": "0.12.66",
+                "phpstan/phpstan": "0.12.80",
                 "phpstan/phpstan-strict-rules": "^0.12.4"
             },
             "type": "library",
@@ -451,7 +451,7 @@
                 "issues": "https://github.com/pmmp/ClassLoader/issues",
                 "source": "https://github.com/pmmp/ClassLoader/tree/master"
             },
-            "time": "2021-01-15T00:41:29+00:00"
+            "time": "2021-04-19T14:36:23+00:00"
         },
         {
             "name": "pocketmine/color",

src/plugin/PharPluginLoader.php

@@ -48,7 +48,10 @@ class PharPluginLoader implements PluginLoader{
 	 * Loads the plugin contained in $file
 	 */
 	public function loadPlugin(string $file) : void{
-		$this->loader->addPath("$file/src");
+		$description = $this->getPluginDescription($file);
+		if($description !== null){
+			$this->loader->addPath($description->getSrcNamespacePrefix(), "$file/src");
+		}
 	}
 
 	/**

src/plugin/PluginDescription.php

@@ -48,6 +48,7 @@ class PluginDescription{
 	private $name;
 	/** @var string */
 	private $main;
+	private string $srcNamespacePrefix = "";
 	/** @var string[] */
 	private $api;
 	/** @var int[] */
@@ -114,6 +115,8 @@ class PluginDescription{
 			throw new PluginException("Invalid Plugin main, cannot start within the PocketMine namespace");
 		}
 
+		$this->srcNamespacePrefix = $plugin["src-namespace-prefix"] ?? "";
+
 		$this->api = array_map("\strval", (array) ($plugin["api"] ?? []));
 		$this->compatibleMcpeProtocols = array_map("\intval", (array) ($plugin["mcpe-protocol"] ?? []));
 		$this->compatibleOperatingSystems = array_map("\strval", (array) ($plugin["os"] ?? []));
@@ -284,6 +287,8 @@ class PluginDescription{
 		return $this->main;
 	}
 
+	public function getSrcNamespacePrefix() : string{ return $this->srcNamespacePrefix; }
+
 	public function getName() : string{
 		return $this->name;
 	}

tests/phpstan/configs/check-explicit-mixed-baseline.neon

@@ -210,6 +210,11 @@ parameters:
 			count: 1
 			path: ../../../src/plugin/PluginDescription.php
 
+		-
+			message: "#^Property pocketmine\\\\plugin\\\\PluginDescription\\:\\:\\$srcNamespacePrefix \\(string\\) does not accept mixed\\.$#"
+			count: 1
+			path: ../../../src/plugin/PluginDescription.php
+
 		-
 			message: "#^Parameter \\#1 \\$plugins of class pocketmine\\\\plugin\\\\PluginGraylist constructor expects array\\<string\\>, mixed given\\.$#"
 			count: 1

tests/plugins/DevTools

@@ -1 +1 @@
-Subproject commit 888d021260efa5456cd7cc0174fb3a2663960811
+Subproject commit dfbea943e1c64094358acac56013b89065884657

tests/plugins/TesterPlugin/plugin.yml

@@ -1,5 +1,6 @@
 name: TesterPlugin
 main: pmmp\TesterPlugin\Main
+src-namespace-prefix: pmmp\TesterPlugin
 version: 0.1.0
 api: [3.2.0, 4.0.0]
 load: POSTWORLD