feat(phpstan): foundation for usage in extensions (#3666)

* feat(phpstan): pick up extended model relations typings
* feat(phpstan): pick up extended model date attributes
* feat(core): introduce `castAttribute` extender
Stops using `dates` as it's deprecated in laravel 8
* feat(phpstan): pick up extended model attributes through casts
* fix: extenders not resolved when declared namespace
* fix(phpstan): new model attributes are always nullable
* chore(phpstan): add helpful cache clearing command
* Apply fixes from StyleCI
* chore: improve extend files provider logic
* chore: rename `castAttribute` to just `cast`
* chore: update phpstan package to detect `cast` method
* Update framework/core/src/Extend/Model.php

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

composer.json

@@ -180,7 +180,8 @@
         }
     },
     "scripts": {
-        "analyse:phpstan": "phpstan analyse"
+        "analyse:phpstan": "phpstan analyse",
+        "clear-cache:phpstan": "phpstan clear-result-cache"
     },
     "scripts-descriptions": {
         "analyse:phpstan": "Run static analysis"

framework/core/src/Database/AbstractModel.php

@@ -54,7 +54,7 @@ abstract class AbstractModel extends Eloquent
     /**
      * @internal
      */
-    public static $dateAttributes = [];
+    public static $customCasts = [];
 
     /**
      * @internal
@@ -100,19 +100,17 @@ abstract class AbstractModel extends Eloquent
     }
 
     /**
-     * Get the attributes that should be converted to dates.
-     *
-     * @return array
+     * {@inheritdoc}
      */
-    public function getDates()
+    public function getCasts()
     {
-        $dates = $this->dates;
+        $casts = parent::getCasts();
 
         foreach (array_merge(array_reverse(class_parents($this)), [static::class]) as $class) {
-            $dates = array_merge($dates, Arr::get(static::$dateAttributes, $class, []));
+            $casts = array_merge($casts, Arr::get(static::$customCasts, $class, []));
         }
 
-        return $dates;
+        return $casts;
     }
 
     /**

framework/core/src/Extend/Model.php

@@ -19,6 +19,7 @@ class Model implements ExtenderInterface
 {
     private $modelClass;
     private $customRelations = [];
+    private $casts = [];
 
     /**
      * @param string $modelClass: The ::class attribute of the model you are modifying.
@@ -34,17 +35,25 @@ class Model implements ExtenderInterface
      *
      * @param string $attribute
      * @return self
+     * @deprecated use `cast` instead. Will be removed in v2.
      */
     public function dateAttribute(string $attribute): self
     {
-        Arr::set(
-            AbstractModel::$dateAttributes,
-            $this->modelClass,
-            array_merge(
-                Arr::get(AbstractModel::$dateAttributes, $this->modelClass, []),
-                [$attribute]
-            )
-        );
+        $this->cast($attribute, 'datetime');
+
+        return $this;
+    }
+
+    /**
+     * Add a custom attribute type cast. Should not be applied to non-extension attributes.
+     *
+     * @param string $attribute: The new attribute name.
+     * @param string $cast: The cast type. See https://laravel.com/docs/8.x/eloquent-mutators#attribute-casting
+     * @return self
+     */
+    public function cast(string $attribute, string $cast): self
+    {
+        $this->casts[$attribute] = $cast;
 
         return $this;
     }
@@ -184,5 +193,14 @@ class Model implements ExtenderInterface
         foreach ($this->customRelations as $name => $callback) {
             Arr::set(AbstractModel::$customRelations, "$this->modelClass.$name", ContainerUtil::wrapCallback($callback, $container));
         }
+
+        Arr::set(
+            AbstractModel::$customCasts,
+            $this->modelClass,
+            array_merge(
+                Arr::get(AbstractModel::$customCasts, $this->modelClass, []),
+                $this->casts
+            )
+        );
     }
 }

framework/core/tests/integration/extenders/ModelTest.php

@@ -375,64 +375,64 @@ class ModelTest extends TestCase
     /**
      * @test
      */
-    public function custom_date_attribute_doesnt_exist_by_default()
+    public function custom_cast_attribute_doesnt_exist_by_default()
     {
         $post = new Post;
 
         $this->app();
 
-        $this->assertNotContains('custom', $post->getDates());
+        $this->assertFalse($post->hasCast('custom'));
     }
 
     /**
      * @test
      */
-    public function custom_date_attribute_can_be_set()
+    public function custom_cast_attribute_can_be_set()
     {
         $this->extend(
             (new Extend\Model(Post::class))
-                ->dateAttribute('custom')
+                ->cast('custom', 'datetime')
         );
 
         $this->app();
 
         $post = new Post;
 
-        $this->assertContains('custom', $post->getDates());
+        $this->assertTrue($post->hasCast('custom', 'datetime'));
     }
 
     /**
      * @test
      */
-    public function custom_date_attribute_is_inherited_to_child_classes()
+    public function custom_cast_attribute_is_inherited_to_child_classes()
     {
         $this->extend(
             (new Extend\Model(Post::class))
-                ->dateAttribute('custom')
+                ->cast('custom', 'boolean')
         );
 
         $this->app();
 
         $post = new CommentPost;
 
-        $this->assertContains('custom', $post->getDates());
+        $this->assertTrue($post->hasCast('custom', 'boolean'));
     }
 
     /**
      * @test
      */
-    public function custom_date_attribute_doesnt_work_if_set_on_unrelated_model()
+    public function custom_cast_attribute_doesnt_work_if_set_on_unrelated_model()
     {
         $this->extend(
             (new Extend\Model(Post::class))
-                ->dateAttribute('custom')
+                ->cast('custom', 'integer')
         );
 
         $this->app();
 
         $discussion = new Discussion;
 
-        $this->assertNotContains('custom', $discussion->getDates());
+        $this->assertFalse($discussion->hasCast('custom', 'integer'));
     }
 }
 

php-packages/phpstan/extension.neon

@@ -15,3 +15,27 @@ parameters:
     - stubs/Illuminate/Contracts/Filesystem/Factory.stub
     - stubs/Illuminate/Contracts/Filesystem/Cloud.stub
     - stubs/Illuminate/Contracts/Filesystem/Filesystem.stub
+
+services:
+	-
+		class: Flarum\PHPStan\Relations\ModelRelationsExtension
+		tags:
+			- phpstan.broker.methodsClassReflectionExtension
+			- phpstan.broker.propertiesClassReflectionExtension
+	-
+		class: Flarum\PHPStan\Attributes\ModelDateAttributesExtension
+		tags:
+			- phpstan.broker.propertiesClassReflectionExtension
+	-
+		class: Flarum\PHPStan\Attributes\ModelCastAttributeExtension
+		tags:
+			- phpstan.broker.propertiesClassReflectionExtension
+	-
+		class: Flarum\PHPStan\Extender\FilesProvider
+		arguments:
+			- %paths%
+	-
+		class: Flarum\PHPStan\Extender\Resolver
+		arguments:
+			- @Flarum\PHPStan\Extender\FilesProvider
+			- @defaultAnalysisParser

php-packages/phpstan/src/Attributes/AttributeProperty.php

@@ -0,0 +1,94 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PHPStan\Attributes;
+
+use PHPStan\Reflection\ClassReflection;
+use PHPStan\Reflection\PropertyReflection;
+use PHPStan\TrinaryLogic;
+use PHPStan\Type\Type;
+
+class AttributeProperty implements PropertyReflection
+{
+    /** @var ClassReflection */
+    private $classReflection;
+    /** @var Type */
+    private $type;
+
+    public function __construct(ClassReflection $classReflection, Type $type)
+    {
+        $this->classReflection = $classReflection;
+        $this->type = $type;
+    }
+
+    public function getDeclaringClass(): ClassReflection
+    {
+        return $this->classReflection;
+    }
+
+    public function isStatic(): bool
+    {
+        return false;
+    }
+
+    public function isPrivate(): bool
+    {
+        return false;
+    }
+
+    public function isPublic(): bool
+    {
+        return true;
+    }
+
+    public function getDocComment(): ?string
+    {
+        return null;
+    }
+
+    public function getReadableType(): Type
+    {
+        return $this->type;
+    }
+
+    public function getWritableType(): Type
+    {
+        return $this->getReadableType();
+    }
+
+    public function canChangeTypeAfterAssignment(): bool
+    {
+        return false;
+    }
+
+    public function isReadable(): bool
+    {
+        return true;
+    }
+
+    public function isWritable(): bool
+    {
+        return true;
+    }
+
+    public function isDeprecated(): TrinaryLogic
+    {
+        return TrinaryLogic::createNo();
+    }
+
+    public function getDeprecatedDescription(): ?string
+    {
+        return null;
+    }
+
+    public function isInternal(): TrinaryLogic
+    {
+        return TrinaryLogic::createNo();
+    }
+}

php-packages/phpstan/src/Attributes/ModelCastAttributeExtension.php

@@ -0,0 +1,87 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PHPStan\Attributes;
+
+use Carbon\Carbon;
+use Flarum\PHPStan\Extender\MethodCall;
+use Flarum\PHPStan\Extender\Resolver;
+use PHPStan\PhpDoc\TypeStringResolver;
+use PHPStan\Reflection\ClassReflection;
+use PHPStan\Reflection\PropertiesClassReflectionExtension;
+use PHPStan\Reflection\PropertyReflection;
+use PHPStan\Type\NullType;
+use PHPStan\Type\ObjectType;
+use PHPStan\Type\UnionType;
+
+class ModelCastAttributeExtension implements PropertiesClassReflectionExtension
+{
+    /** @var Resolver */
+    private $extendersResolver;
+    /** @var TypeStringResolver */
+    private $typeStringResolver;
+
+    public function __construct(Resolver $extendersResolver, TypeStringResolver $typeStringResolver)
+    {
+        $this->extendersResolver = $extendersResolver;
+        $this->typeStringResolver = $typeStringResolver;
+    }
+
+    public function hasProperty(ClassReflection $classReflection, string $propertyName): bool
+    {
+        return $this->findCastAttributeMethod($classReflection, $propertyName) !== null;
+    }
+
+    public function getProperty(ClassReflection $classReflection, string $propertyName): PropertyReflection
+    {
+        return $this->resolveCastAttributeProperty($this->findCastAttributeMethod($classReflection, $propertyName), $classReflection);
+    }
+
+    private function findCastAttributeMethod(ClassReflection $classReflection, string $propertyName): ?MethodCall
+    {
+        foreach ($this->extendersResolver->getExtenders() as $extender) {
+            if (! $extender->isExtender('Model')) {
+                continue;
+            }
+
+            foreach (array_merge([$classReflection->getName()], $classReflection->getParentClassesNames()) as $className) {
+                if ($className === 'Flarum\Database\AbstractModel') {
+                    break;
+                }
+
+                if ($extender->extends($className)) {
+                    if ($methodCalls = $extender->findMethodCalls('cast')) {
+                        foreach ($methodCalls as $methodCall) {
+                            if ($methodCall->arguments[0]->value === $propertyName) {
+                                return $methodCall;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        return null;
+    }
+
+    private function resolveCastAttributeProperty(MethodCall $methodCall, ClassReflection $classReflection): PropertyReflection
+    {
+        $typeName = $methodCall->arguments[1]->value;
+        $type = $this->typeStringResolver->resolve("$typeName|null");
+
+        if (str_contains($typeName, 'date') || $typeName === 'timestamp') {
+            $type = new UnionType([
+                new ObjectType(Carbon::class),
+                new NullType(),
+            ]);
+        }
+
+        return new AttributeProperty($classReflection, $type);
+    }
+}

php-packages/phpstan/src/Attributes/ModelDateAttributesExtension.php

@@ -0,0 +1,76 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PHPStan\Attributes;
+
+use Carbon\Carbon;
+use Flarum\PHPStan\Extender\MethodCall;
+use Flarum\PHPStan\Extender\Resolver;
+use PHPStan\Reflection\ClassReflection;
+use PHPStan\Reflection\PropertiesClassReflectionExtension;
+use PHPStan\Reflection\PropertyReflection;
+use PHPStan\Type\NullType;
+use PHPStan\Type\ObjectType;
+use PHPStan\Type\UnionType;
+
+class ModelDateAttributesExtension implements PropertiesClassReflectionExtension
+{
+    /** @var Resolver */
+    private $extendersResolver;
+
+    public function __construct(Resolver $extendersResolver)
+    {
+        $this->extendersResolver = $extendersResolver;
+    }
+
+    public function hasProperty(ClassReflection $classReflection, string $propertyName): bool
+    {
+        return $this->findDateAttributeMethod($classReflection, $propertyName) !== null;
+    }
+
+    public function getProperty(ClassReflection $classReflection, string $propertyName): PropertyReflection
+    {
+        return $this->resolveDateAttributeProperty($this->findDateAttributeMethod($classReflection, $propertyName), $classReflection);
+    }
+
+    private function findDateAttributeMethod(ClassReflection $classReflection, string $propertyName): ?MethodCall
+    {
+        foreach ($this->extendersResolver->getExtenders() as $extender) {
+            if (! $extender->isExtender('Model')) {
+                continue;
+            }
+
+            foreach (array_merge([$classReflection->getName()], $classReflection->getParentClassesNames()) as $className) {
+                if ($className === 'Flarum\Database\AbstractModel') {
+                    break;
+                }
+
+                if ($extender->extends($className)) {
+                    if ($methodCalls = $extender->findMethodCalls('dateAttribute')) {
+                        foreach ($methodCalls as $methodCall) {
+                            if ($methodCall->arguments[0]->value === $propertyName) {
+                                return $methodCall;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        return null;
+    }
+
+    private function resolveDateAttributeProperty(MethodCall $methodCall, ClassReflection $classReflection): PropertyReflection
+    {
+        return new AttributeProperty($classReflection, new UnionType([
+            new ObjectType(Carbon::class),
+            new NullType(),
+        ]));
+    }
+}

php-packages/phpstan/src/Extender/Extender.php

@@ -0,0 +1,73 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PHPStan\Extender;
+
+use PhpParser\Node\Expr;
+use PhpParser\Node\Scalar;
+
+class Extender
+{
+    /** @var string */
+    public $qualifiedClassName;
+    /** @var Expr[] */
+    public $constructorArguments;
+    /** @var MethodCall[] */
+    public $methodCalls;
+
+    public function __construct(string $qualifiedClassName, array $constructorArguments = [], array $methodCalls = [])
+    {
+        $this->qualifiedClassName = $qualifiedClassName;
+        $this->constructorArguments = $constructorArguments;
+        $this->methodCalls = $methodCalls;
+    }
+
+    public function isExtender(string $className): bool
+    {
+        return $this->qualifiedClassName === "Flarum\\Extend\\$className";
+    }
+
+    public function extends(...$args): bool
+    {
+        foreach ($this->constructorArguments as $index => $constructorArgument) {
+            $string = null;
+
+            switch (get_class($constructorArgument)) {
+                case Expr\ClassConstFetch::class:
+                    $string = $constructorArgument->class->toString();
+                    break;
+                case Scalar\String_::class:
+                    $string = $constructorArgument->value;
+                    break;
+                default:
+                    $string = $constructorArgument;
+            }
+
+            if ($string !== $args[$index]) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    /** @return MethodCall[] */
+    public function findMethodCalls(string ...$methods): array
+    {
+        $methodCalls = [];
+
+        foreach ($this->methodCalls as $methodCall) {
+            if (in_array($methodCall->methodName, $methods)) {
+                $methodCalls[] = $methodCall;
+            }
+        }
+
+        return $methodCalls;
+    }
+}

php-packages/phpstan/src/Extender/FilesProvider.php

@@ -0,0 +1,45 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PHPStan\Extender;
+
+class FilesProvider
+{
+    /** @var string[] */
+    private $cachedExtenderFiles;
+    /** @var string[] */
+    private $paths;
+
+    public function __construct(array $paths)
+    {
+        $this->paths = $paths;
+    }
+
+    public function getExtenderFiles(): array
+    {
+        if ($this->cachedExtenderFiles === null) {
+            $this->cachedExtenderFiles = $this->findExtenderFiles();
+        }
+
+        return $this->cachedExtenderFiles;
+    }
+
+    private function findExtenderFiles(): array
+    {
+        $extenderFiles = [];
+
+        foreach ($this->paths as $path) {
+            if (str_contains($path, 'extend.php') && file_exists($path)) {
+                $extenderFiles[] = $path;
+            }
+        }
+
+        return $extenderFiles;
+    }
+}

php-packages/phpstan/src/Extender/MethodCall.php

@@ -0,0 +1,24 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PHPStan\Extender;
+
+class MethodCall
+{
+    /** @var string */
+    public $methodName;
+    /** @var array */
+    public $arguments;
+
+    public function __construct(string $methodName, array $arguments = [])
+    {
+        $this->methodName = $methodName;
+        $this->arguments = $arguments;
+    }
+}

php-packages/phpstan/src/Extender/Resolver.php

@@ -0,0 +1,138 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PHPStan\Extender;
+
+use Flarum\PHPStan\Extender\MethodCall as ExtenderMethodCall;
+use PhpParser\Node\Arg;
+use PhpParser\Node\Expr\Array_;
+use PhpParser\Node\Expr\MethodCall;
+use PhpParser\Node\Expr\New_;
+use PhpParser\Node\Stmt\Namespace_;
+use PhpParser\Node\Stmt\Return_;
+use PHPStan\Parser\Parser;
+use PHPStan\Parser\ParserErrorsException;
+
+class Resolver
+{
+    /** @var Extender[] */
+    private $cachedExtenders = [];
+    /** @var FilesProvider */
+    private $extenderFilesProvider;
+    /** @var Parser */
+    private $parser;
+
+    public function __construct(FilesProvider $extenderFilesProvider, Parser $parser)
+    {
+        $this->extenderFilesProvider = $extenderFilesProvider;
+        $this->parser = $parser;
+    }
+
+    public function getExtenders(): array
+    {
+        if ($this->cachedExtenders) {
+            return $this->cachedExtenders;
+        }
+
+        return $this->cachedExtenders = $this->resolveExtenders();
+    }
+
+    public function getExtendersFor(string $extenderClass, ...$args): array
+    {
+        $extenders = [];
+
+        foreach ($this->getExtenders() as $extender) {
+            if ($extender->isExtender($extenderClass)) {
+                $extenders[] = $extender;
+            }
+        }
+
+        return $extenders;
+    }
+
+    private function resolveExtenders(): array
+    {
+        $extenders = [];
+
+        foreach ($this->extenderFilesProvider->getExtenderFiles() as $extenderFile) {
+            $extenders = array_merge($extenders, $this->resolveExtendersFromFile($extenderFile));
+        }
+
+        return $extenders;
+    }
+
+    /**
+     * @return Extender[]
+     * @throws ParserErrorsException
+     * @throws \Exception
+     */
+    private function resolveExtendersFromFile($extenderFile): array
+    {
+        /** @var Extender[] $extenders */
+        $extenders = [];
+
+        $statements = $this->parser->parseFile($extenderFile);
+
+        if ($statements[0] instanceof Namespace_) {
+            $statements = $statements[0]->stmts;
+        }
+
+        foreach ($statements as $statement) {
+            if ($statement instanceof Return_) {
+                $expression = $statement->expr;
+
+                if ($expression instanceof Array_) {
+                    foreach ($expression->items as $item) {
+                        if ($item->value instanceof MethodCall) {
+                            $extenders[] = $this->resolveExtender($item->value);
+                        }
+                    }
+                }
+            }
+        }
+
+        return $extenders;
+    }
+
+    private function resolveExtenderNew(New_ $var, array $methodCalls = []): Extender
+    {
+        return new Extender($var->class->toString(), array_map(function (Arg $arg) {
+            $arg->value->setAttributes([]);
+
+            return $arg->value;
+        }, $var->args), $methodCalls);
+    }
+
+    private function resolveMethod(MethodCall $var): ExtenderMethodCall
+    {
+        return new ExtenderMethodCall($var->name->toString(), array_map(function (Arg $arg) {
+            $arg->value->setAttributes([]);
+
+            return $arg->value;
+        }, $var->args));
+    }
+
+    private function resolveExtender(MethodCall $value): Extender
+    {
+        $methodStack = [$this->resolveMethod($value)];
+
+        while ($value->var instanceof MethodCall) {
+            $methodStack[] = $this->resolveMethod($value->var);
+            $value = $value->var;
+        }
+
+        $methodStack = array_reverse($methodStack);
+
+        if (! $value->var instanceof New_) {
+            throw new \Exception('Unable to resolve extender for '.get_class($value->var));
+        }
+
+        return $this->resolveExtenderNew($value->var, $methodStack);
+    }
+}

php-packages/phpstan/src/Relations/ModelRelationsExtension.php

@@ -0,0 +1,86 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PHPStan\Relations;
+
+use Flarum\PHPStan\Extender\MethodCall;
+use Flarum\PHPStan\Extender\Resolver;
+use PHPStan\Reflection\ClassReflection;
+use PHPStan\Reflection\MethodReflection;
+use PHPStan\Reflection\MethodsClassReflectionExtension;
+use PHPStan\Reflection\PropertiesClassReflectionExtension;
+use PHPStan\Reflection\PropertyReflection;
+
+class ModelRelationsExtension implements MethodsClassReflectionExtension, PropertiesClassReflectionExtension
+{
+    /** @var Resolver */
+    private $extendersResolver;
+
+    public function __construct(Resolver $extendersResolver)
+    {
+        $this->extendersResolver = $extendersResolver;
+    }
+
+    public function hasMethod(ClassReflection $classReflection, string $methodName): bool
+    {
+        return $this->findRelationMethod($classReflection, $methodName) !== null;
+    }
+
+    public function getMethod(ClassReflection $classReflection, string $methodName): MethodReflection
+    {
+        return $this->resolveRelationMethod($this->findRelationMethod($classReflection, $methodName), $classReflection);
+    }
+
+    public function hasProperty(ClassReflection $classReflection, string $propertyName): bool
+    {
+        return $this->findRelationMethod($classReflection, $propertyName) !== null;
+    }
+
+    public function getProperty(ClassReflection $classReflection, string $propertyName): \PHPStan\Reflection\PropertyReflection
+    {
+        return $this->resolveRelationProperty($this->findRelationMethod($classReflection, $propertyName), $classReflection);
+    }
+
+    private function findRelationMethod(ClassReflection $classReflection, string $methodName): ?MethodCall
+    {
+        foreach ($this->extendersResolver->getExtenders() as $extender) {
+            if (! $extender->isExtender('Model')) {
+                continue;
+            }
+
+            foreach (array_merge([$classReflection->getName()], $classReflection->getParentClassesNames()) as $className) {
+                if ($className === 'Flarum\Database\AbstractModel') {
+                    break;
+                }
+
+                if ($extender->extends($className)) {
+                    if ($methodCalls = $extender->findMethodCalls('belongsTo', 'belongsToMany', 'hasMany', 'hasOne')) {
+                        foreach ($methodCalls as $methodCall) {
+                            if ($methodCall->arguments[0]->value === $methodName) {
+                                return $methodCall;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        return null;
+    }
+
+    private function resolveRelationMethod(MethodCall $methodCall, ClassReflection $classReflection): MethodReflection
+    {
+        return new RelationMethod($methodCall, $classReflection);
+    }
+
+    private function resolveRelationProperty(MethodCall $methodCall, ClassReflection $classReflection): PropertyReflection
+    {
+        return new RelationProperty($methodCall, $classReflection);
+    }
+}

php-packages/phpstan/src/Relations/RelationMethod.php

@@ -0,0 +1,132 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PHPStan\Relations;
+
+use Flarum\PHPStan\Extender\MethodCall;
+use PHPStan\Reflection\ClassMemberReflection;
+use PHPStan\Reflection\ClassReflection;
+use PHPStan\Reflection\FunctionVariant;
+use PHPStan\Reflection\MethodReflection;
+use PHPStan\TrinaryLogic;
+use PHPStan\Type\Generic\GenericObjectType;
+use PHPStan\Type\Generic\TemplateTypeMap;
+use PHPStan\Type\ObjectType;
+use PHPStan\Type\Type;
+
+class RelationMethod implements MethodReflection
+{
+    /** @var MethodCall */
+    private $methodCall;
+    /** @var ClassReflection */
+    private $classReflection;
+
+    public function __construct(MethodCall $methodCall, ClassReflection $classReflection)
+    {
+        $this->methodCall = $methodCall;
+        $this->classReflection = $classReflection;
+    }
+
+    public function getDeclaringClass(): ClassReflection
+    {
+        return $this->classReflection;
+    }
+
+    public function isStatic(): bool
+    {
+        return false;
+    }
+
+    public function isPrivate(): bool
+    {
+        return false;
+    }
+
+    public function isPublic(): bool
+    {
+        return true;
+    }
+
+    public function getDocComment(): ?string
+    {
+        return null;
+    }
+
+    public function getName(): string
+    {
+        return $this->methodCall->arguments[0]->value;
+    }
+
+    public function getPrototype(): ClassMemberReflection
+    {
+        return $this;
+    }
+
+    public function getVariants(): array
+    {
+        $returnType = 'Illuminate\Database\Eloquent\Relations\Relation';
+
+        switch ($this->methodCall->methodName) {
+            case 'belongsTo':
+                $returnType = 'Illuminate\Database\Eloquent\Relations\BelongsTo';
+                break;
+            case 'belongsToMany':
+                $returnType = 'Illuminate\Database\Eloquent\Relations\BelongsToMany';
+                break;
+            case 'hasMany':
+                $returnType = 'Illuminate\Database\Eloquent\Relations\HasMany';
+                break;
+            case 'hasOne':
+                $returnType = 'Illuminate\Database\Eloquent\Relations\HasOne';
+                break;
+        }
+
+        $relationTarget = $this->methodCall->arguments[1]->class->toString();
+
+        return [
+            new FunctionVariant(
+                TemplateTypeMap::createEmpty(),
+                null,
+                [],
+                false,
+                new GenericObjectType($returnType, [new ObjectType($relationTarget)])
+            ),
+        ];
+    }
+
+    public function isDeprecated(): TrinaryLogic
+    {
+        return TrinaryLogic::createNo();
+    }
+
+    public function getDeprecatedDescription(): ?string
+    {
+        return null;
+    }
+
+    public function isFinal(): TrinaryLogic
+    {
+        return TrinaryLogic::createNo();
+    }
+
+    public function isInternal(): TrinaryLogic
+    {
+        return TrinaryLogic::createNo();
+    }
+
+    public function getThrowType(): ?Type
+    {
+        return null;
+    }
+
+    public function hasSideEffects(): TrinaryLogic
+    {
+        return TrinaryLogic::createNo();
+    }
+}

php-packages/phpstan/src/Relations/RelationProperty.php

@@ -0,0 +1,110 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PHPStan\Relations;
+
+use Exception;
+use Flarum\PHPStan\Extender\MethodCall;
+use Illuminate\Database\Eloquent\Collection;
+use PHPStan\Reflection\ClassReflection;
+use PHPStan\Reflection\PropertyReflection;
+use PHPStan\TrinaryLogic;
+use PHPStan\Type\Generic\GenericObjectType;
+use PHPStan\Type\ObjectType;
+use PHPStan\Type\Type;
+
+class RelationProperty implements PropertyReflection
+{
+    /** @var MethodCall */
+    private $methodCall;
+    /** @var ClassReflection */
+    private $classReflection;
+
+    public function __construct(MethodCall $methodCall, ClassReflection $classReflection)
+    {
+        $this->methodCall = $methodCall;
+        $this->classReflection = $classReflection;
+    }
+
+    public function getDeclaringClass(): ClassReflection
+    {
+        return $this->classReflection;
+    }
+
+    public function isStatic(): bool
+    {
+        return false;
+    }
+
+    public function isPrivate(): bool
+    {
+        return false;
+    }
+
+    public function isPublic(): bool
+    {
+        return true;
+    }
+
+    public function getDocComment(): ?string
+    {
+        return null;
+    }
+
+    public function getReadableType(): Type
+    {
+        switch ($this->methodCall->methodName) {
+            case 'hasMany':
+            case 'belongsToMany':
+                return new GenericObjectType(Collection::class, [new ObjectType($this->methodCall->arguments[1]->class->toString())]);
+
+            case 'hasOne':
+            case 'belongsTo':
+                return new ObjectType($this->methodCall->arguments[1]->class->toString());
+
+            default:
+                throw new Exception('Unknown relationship type for relation: '.$this->methodCall->methodName);
+        }
+    }
+
+    public function getWritableType(): Type
+    {
+        return $this->getReadableType();
+    }
+
+    public function canChangeTypeAfterAssignment(): bool
+    {
+        return false;
+    }
+
+    public function isReadable(): bool
+    {
+        return true;
+    }
+
+    public function isWritable(): bool
+    {
+        return true;
+    }
+
+    public function isDeprecated(): TrinaryLogic
+    {
+        return TrinaryLogic::createNo();
+    }
+
+    public function getDeprecatedDescription(): ?string
+    {
+        return null;
+    }
+
+    public function isInternal(): TrinaryLogic
+    {
+        return TrinaryLogic::createNo();
+    }
+}