fix: corrected return type of MorphToMany methods (larastan#699)

extension.neon

@@ -166,7 +166,7 @@ services:
             - phpstan.broker.dynamicMethodReturnTypeExtension
 
     -
-        class: NunoMaduro\Larastan\ReturnTypes\RelationExtension
+        class: NunoMaduro\Larastan\ReturnTypes\RelationCollectionExtension
         tags:
             - phpstan.broker.dynamicMethodReturnTypeExtension
 

src/ReturnTypes/RelationExtension.php → src/ReturnTypes/RelationCollectionExtension.php

@@ -11,6 +11,7 @@
 use PhpParser\Node\Expr\MethodCall;
 use PHPStan\Analyser\Scope;
 use PHPStan\Reflection\MethodReflection;
+use PHPStan\Reflection\ParametersAcceptorSelector;
 use PHPStan\Type\DynamicMethodReturnTypeExtension;
 use PHPStan\Type\Generic\GenericObjectType;
 use PHPStan\Type\ObjectType;
@@ -19,7 +20,7 @@
 /**
  * @internal
  */
-final class RelationExtension implements DynamicMethodReturnTypeExtension
+final class RelationCollectionExtension implements DynamicMethodReturnTypeExtension
 {
     /** @var BuilderHelper */
     private $builderHelper;
@@ -52,6 +53,12 @@ public function isMethodSupported(MethodReflection $methodReflection): bool
             return false;
         }
 
+        $returnType = ParametersAcceptorSelector::selectSingle($methodReflection->getVariants())->getReturnType();
+
+        if (! in_array(Collection::class, $returnType->getReferencedClasses(), true)) {
+            return false;
+        }
+
         return $methodReflection->getDeclaringClass()->hasNativeMethod($methodReflection->getName());
     }
 
@@ -66,7 +73,7 @@ public function getTypeFromMethodCall(
         /** @var ObjectType $modelType */
         $modelType = $methodReflection->getDeclaringClass()->getActiveTemplateTypeMap()->getType('TRelatedModel');
 
-        $returnType = $methodReflection->getVariants()[0]->getReturnType();
+        $returnType = ParametersAcceptorSelector::selectSingle($methodReflection->getVariants())->getReturnType();
 
         if (in_array(Collection::class, $returnType->getReferencedClasses(), true)) {
             $collectionClassName = $this->builderHelper->determineCollectionClassName($modelType->getClassname());

tests/Features/Models/Relations.php

@@ -14,6 +14,7 @@
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 use Illuminate\Database\Eloquent\Relations\HasMany;
 use Illuminate\Database\Eloquent\Relations\MorphTo;
+use Illuminate\Database\Eloquent\Relations\MorphToMany;
 
 class Relations
 {
@@ -186,6 +187,22 @@ public function testWithoutTrashedWithBelongsToRelation(User $user): BelongsTo
     {
         return $user->group()->withoutTrashed();
     }
+
+    /**
+     * @phpstan-return MorphToMany<Address>
+     */
+    public function testMorphToManyWithTimestamps(Tag $tag): MorphToMany
+    {
+        return $tag->addresses();
+    }
+
+    /**
+     * @phpstan-return MorphToMany<Address>
+     */
+    public function testMorphToManyWithPivot(Tag $tag): MorphToMany
+    {
+        return $tag->addresses();
+    }
 }
 
 /**
@@ -210,33 +227,27 @@ public function relation(): HasMany
     {
         return $this->hasMany(User::class);
     }
-
-    public function addRelation(): User
-    {
-        return $this->relation()->create([]);
-    }
 }
 
-class TestRelationCreateOnExistingModel
+class Tag extends Model
 {
-    /** @var User */
-    private $user;
-
-    public function testRelationCreateOnExistingModel(): Account
+    /**
+     * @phpstan-return MorphToMany<Address>
+     */
+    public function addresses(): MorphToMany
     {
-        return $this->user->accounts()->create();
+        return $this->morphToMany(Address::class, 'taggable')->withTimestamps();
     }
-}
 
-class Post extends Model
-{
-    public function author(): BelongsTo
+    /**
+     * @phpstan-return MorphToMany<Address>
+     */
+    public function addressesWithPivot(): MorphToMany
     {
-        return $this->belongsTo(User::class);
+        return $this->morphToMany(Address::class, 'taggable')->withPivot('foo');
     }
+}
 
-    public function addUser(User $user): self
-    {
-        return $this->author()->associate($user);
-    }
+class Address extends Model
+{
 }