[5.6] Throw exception for has() with MorphTo relationship

src/Illuminate/Database/Eloquent/Concerns/QueriesRelationships.php

@@ -3,9 +3,11 @@
 namespace Illuminate\Database\Eloquent\Concerns;
 
 use Closure;
+use RuntimeException;
 use Illuminate\Support\Str;
 use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Query\Expression;
+use Illuminate\Database\Eloquent\Relations\MorphTo;
 use Illuminate\Database\Eloquent\Relations\Relation;
 use Illuminate\Database\Query\Builder as QueryBuilder;
 
@@ -29,6 +31,10 @@ public function has($relation, $operator = '>=', $count = 1, $boolean = 'and', C
 
         $relation = $this->getRelationWithoutConstraints($relation);
 
+        if ($relation instanceof MorphTo) {
+            throw new RuntimeException('has() and whereHas() do not support MorphTo relationships.');
+        }
+
         // If we only need to check for the existence of the relation, then we can optimize
         // the subquery to only run a "where exists" clause instead of this full "count"
         // clause. This will make these queries run much faster compared with a count.

tests/Database/DatabaseEloquentIntegrationTest.php

@@ -717,6 +717,14 @@ public function testHasWithNonWhereBindings()
         $this->assertEquals($questionMarksCount, $bindingsCount);
     }
 
+    /**
+     * @expectedException \RuntimeException
+     */
+    public function testHasOnMorphToRelationship()
+    {
+        EloquentTestPhoto::has('imageable')->get();
+    }
+
     public function testBelongsToManyRelationshipModelsAreProperlyHydratedOverChunkedRequest()
     {
         $user = EloquentTestUser::create(['email' => 'taylorotwell@gmail.com']);