[13.x] Generate plural morph pivot table name (#56832)

* Update test to use 'MorphPivot' model for pivot

* Only generate a singular table name for non-morph pivots

Author: willrowe

src/Illuminate/Database/Eloquent/Relations/Concerns/AsPivot.php

@@ -3,6 +3,7 @@
 namespace Illuminate\Database\Eloquent\Relations\Concerns;
 
 use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\MorphPivot;
 use Illuminate\Support\Str;
 
 trait AsPivot
@@ -166,13 +167,13 @@ protected function getDeleteQuery()
      */
     public function getTable()
     {
-        if (! isset($this->table)) {
+        if (! isset($this->table) && (! $this instanceof MorphPivot)) {
             $this->setTable(str_replace(
                 '\\', '', Str::snake(Str::singular(class_basename($this)))
             ));
         }
 
-        return $this->table;
+        return parent::getTable();
     }
 
     /**

tests/Database/DatabaseEloquentIntegrationTest.php

@@ -2834,10 +2834,14 @@ public function parentPost()
 
     public function tags()
     {
-        return $this->morphToMany(EloquentTestTag::class, 'taggable', null, null, 'tag_id')->withPivot('taxonomy');
+        return $this->morphToMany(EloquentTestTag::class, 'taggable', Taggable::class, null, 'tag_id')->withPivot('taxonomy');
     }
 }
 
+class Taggable extends MorphPivot
+{
+}
+
 class EloquentTestTag extends Eloquent
 {
     protected $table = 'tags';