Modular config files

This change introduces an option to have the configuration split across
several files using standard XInclude tags. This may be useful for more
complex configs, or to include auto-generated parts into a manually
written config file.

docs/running_psalm/configuration.md

@@ -11,6 +11,29 @@ Psalm uses an XML config file (by default, `psalm.xml`). A barebones example loo
 </psalm>
 ```
 
+Configuration file may be split into several files using [XInclude](https://www.w3.org/TR/xinclude/) tags (c.f. previous example):
+#### psalm.xml
+```xml
+<?xml version="1.0"?>
+<psalm
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="https://getpsalm.org/schema/config"
+    xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
+    xmlns:xi="http://www.w3.org/2001/XInclude"
+>
+    <xi:include href="files.xml"/>
+</psalm>
+```
+#### files.xml
+```xml
+<?xml version="1.0" encoding="UTF-8"?>
+<projectFiles xmlns="https://getpsalm.org/schema/config">
+    <file name="Bar.php" />
+    <file name="Bat.php" />
+</projectFiles>
+```
+
+
 ## Optional `<psalm />` attributes
 
 ### Coding style

src/Psalm/Config.php

@@ -7,6 +7,8 @@
 use function array_unique;
 use function class_exists;
 use Composer\Autoload\ClassLoader;
+use DOMDocument;
+
 use function count;
 use const DIRECTORY_SEPARATOR;
 use function dirname;
@@ -65,6 +67,9 @@
 use function trigger_error;
 use function unlink;
 use function version_compare;
+use function getcwd;
+use function chdir;
+use function simplexml_import_dom;
 
 class Config
 {
@@ -605,25 +610,39 @@ public static function loadFromXML($base_dir, $file_contents, $current_dir = nul
             $current_dir = $base_dir;
         }
 
-        self::validateXmlConfig($file_contents);
+        self::validateXmlConfig($base_dir, $file_contents);
 
         return self::fromXmlAndPaths($base_dir, $file_contents, $current_dir);
     }
 
+    private static function loadDomDocument(string $base_dir, string $file_contents): DOMDocument
+    {
+        $dom_document = new DOMDocument();
+
+        // there's no obvious way to set xml:base for a document when loading it from string
+        // so instead we're changing the current directory instead to be able to process XIncludes
+        $oldpwd = getcwd();
+        chdir($base_dir);
+
+        $dom_document->loadXML($file_contents, LIBXML_NONET);
+        $dom_document->xinclude(LIBXML_NONET);
+
+        chdir($oldpwd);
+        return $dom_document;
+    }
 
     /**
      * @throws ConfigException
      */
-    private static function validateXmlConfig(string $file_contents): void
+    private static function validateXmlConfig(string $base_dir, string $file_contents): void
     {
         $schema_path = dirname(dirname(__DIR__)) . '/config.xsd';
 
         if (!file_exists($schema_path)) {
             throw new ConfigException('Cannot locate config schema');
         }
 
-        $dom_document = new \DOMDocument();
-        $dom_document->loadXML($file_contents);
+        $dom_document = self::loadDomDocument($base_dir, $file_contents);
 
         $psalm_nodes = $dom_document->getElementsByTagName('psalm');
 
@@ -640,8 +659,7 @@ private static function validateXmlConfig(string $file_contents): void
             $psalm_node->setAttribute('xmlns', 'https://getpsalm.org/schema/config');
 
             $old_dom_document = $dom_document;
-            $dom_document = new \DOMDocument();
-            $dom_document->loadXML($old_dom_document->saveXML());
+            $dom_document = self::loadDomDocument($base_dir, $old_dom_document->saveXML());
         }
 
         // Enable user error handling
@@ -674,7 +692,9 @@ private static function fromXmlAndPaths(string $base_dir, string $file_contents,
     {
         $config = new static();
 
-        $config_xml = new SimpleXMLElement($file_contents);
+        $dom_document = self::loadDomDocument($base_dir, $file_contents);
+
+        $config_xml = simplexml_import_dom($dom_document);
 
         $booleanAttributes = [
             'useDocblockTypes' => 'use_docblock_types',

tests/Config/ConfigTest.php

@@ -1195,6 +1195,20 @@ public function testTemplatedFiles()
         }
     }
 
+    /** @return void */
+    public function testModularConfig()
+    {
+        $root = __DIR__ . '/../fixtures/ModularConfig';
+        $config = Config::loadFromXMLFile($root . '/psalm.xml', $root);
+        $this->assertEquals(
+            [
+                realpath($root . '/Bar.php'),
+                realpath($root . '/Bat.php')
+            ],
+            $config->getProjectFiles()
+        );
+    }
+
     public function tearDown(): void
     {
         parent::tearDown();

tests/fixtures/ModularConfig/Bar.php

@@ -0,0 +1,23 @@
+<?php
+namespace Vimeo\Test\DummyProject;
+
+class Bar
+{
+    use SomeTrait;
+
+    /** @var string */
+    public $x;
+
+    public function __construct()
+    {
+        $this->x = 'hello';
+    }
+}
+
+/**
+ * @return void
+ */
+function someFunction()
+{
+    echo 'here';
+}

tests/fixtures/ModularConfig/Bat.php

@@ -0,0 +1,13 @@
+<?php
+namespace Vimeo\Test\DummyProject;
+
+class Bat
+{
+    public function __construct()
+    {
+        $a = new Bar();
+
+        someFunction();
+        someOtherFunction();
+    }
+}

tests/fixtures/ModularConfig/SomeTrait.php

@@ -0,0 +1,14 @@
+<?php
+namespace Vimeo\Test\DummyProject;
+
+trait SomeTrait
+{
+}
+
+/**
+ * @return void
+ */
+function someOtherFunction()
+{
+    echo 'here';
+}

tests/fixtures/ModularConfig/files.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<projectFiles xmlns="https://getpsalm.org/schema/config">
+    <file name="Bar.php" />
+    <file name="Bat.php" />
+</projectFiles>

tests/fixtures/ModularConfig/psalm.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0"?>
+<psalm
+    totallyTyped="true"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="https://getpsalm.org/schema/config"
+    xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
+    xmlns:xi="http://www.w3.org/2001/XInclude"
+>
+    <xi:include href="files.xml"/>
+</psalm>