allow insert..select (insertUsing()) to have empty $columns

Enables queries which insert *all* columns from the source table into the destination table, e.g. "insert into users select * from users”, when the table schemas exactly match.

src/Illuminate/Database/Query/Grammars/Grammar.php

@@ -1062,7 +1062,13 @@ public function compileInsertGetId(Builder $query, $values, $sequence)
      */
     public function compileInsertUsing(Builder $query, array $columns, string $sql)
     {
-        return "insert into {$this->wrapTable($query->from)} ({$this->columnize($columns)}) $sql";
+        $table = $this->wrapTable($query->from);
+
+        if (empty($columns)) {
+            return "insert into {$table} $sql";
+        }
+
+        return "insert into {$table} ({$this->columnize($columns)}) $sql";
     }
 
     /**

tests/Database/DatabaseQueryBuilderTest.php

@@ -2793,6 +2793,21 @@ function (Builder $query) {
 
         $this->assertEquals(1, $result);
     }
+
+    public function testInsertUsingWithEmptyColumns()
+    {
+        $builder = $this->getBuilder();
+        $builder->getConnection()->shouldReceive('affectingStatement')->once()->with('insert into "table1" select * from "table2" where "foreign_id" = ?', [5])->andReturn(1);
+
+        $result = $builder->from('table1')->insertUsing(
+            [],
+            function (Builder $query) {
+                $query->from('table2')->where('foreign_id', '=', 5);
+            }
+        );
+
+        $this->assertEquals(1, $result);
+    }
 
     public function testInsertUsingInvalidSubquery()
     {