Printing anonymous classes removes newlines between methods

[bakerkretzmar]

Working on https://github.com/tighten/tlint, Tighten's internal code style and formatting tool, we noticed that the pretty printer removes newlines between methods of anonymous classes.

We're attempting a transformation like this:

<?php

use Illuminate\Database\Migrations\Migration;

- class CreateBuyRequestsTable extends Migration
+ return new class extends Migration
{
    public function up()
    {
        //
    }

    public function down()
    {
        //
    }
- }
+ };

The code we're using for the transformation looks like this:

$traverser = new NodeTraverser;
$traverser->addVisitor(new CloningVisitor);

$originalStatements = $parser->parse($this->code);

$statements = array_map(function (Node $node) {
    if (
        $node instanceof Class_
            && $node->extends->toString() === 'Migration'
            && $node->name
    ) {
        return new Return_(new New_($node));
    }

    return $node;
}, $traverser->traverse($originalStatements));

return (new Standard)->printFormatPreserving($statements, $originalStatements, $lexer->getTokens());

It works, except that the new line between the up() and down() methods is being removed as well.

Is this a bug in the printer or are we doing something wrong? Thanks!

[echoWangyx]

I have the same problem