PHPStan formatter grouping errors by error type

SummaryErrorFormatter.php

<?php declare(strict_types = 1);
namespace App\PHPStan;
use PHPStan\Command\AnalysisResult;
use PHPStan\Command\ErrorFormatter\ErrorFormatter;
use Symfony\Component\Console\Style\OutputStyle;
class SummaryErrorFormatter implements ErrorFormatter
{
	public function formatErrors(
		AnalysisResult $analysisResult,
		OutputStyle $style
	): int
	{
		if (!$analysisResult->hasErrors()) {
			return 0;
		}
		foreach ($analysisResult->getNotFileSpecificErrors() as $notFileSpecificError) {
			$style->writeln(sprintf('?:?:%s', $notFileSpecificError));
		}
		$errorsList=[];
		foreach ($analysisResult->getFileSpecificErrors() as $fileSpecificError) {
			// this regular expressions are suboptimal and not covering everything
			//just a quick solution to test if such view is useful
			$index = preg_replace(
				'#[a-zA-Z_\:()\|]*\\\[a-zA-Z_\:()\]]*|\$[a-zA-Z_]*|offset [\d]*|[A-Z_]{5,}#',
				'?',
				$fileSpecificError->getMessage()
			);
			$index = preg_replace('#[a-zA-Z]*\([.]*\)#', '?', $index);
			$index = preg_replace(
				'/mixed|int|string|float|DateTime|array|bool|null|\#[0-9]+|\(.*\)|[^\s]*::__|[^\s]*::|\"[^\"]*\"/',
				'?',
				$index
			);
			$index = preg_replace('#[\?\|]+#', '?', $index);
			$errorsList[$index][] = sprintf(
				'%s:%d %s',
				$fileSpecificError->getFile(),
				$fileSpecificError->getLine() ?? '?',
				$fileSpecificError->getMessage()
				);
		}
		$errorTypesCount = count($errorsList);
		foreach ($errorsList as $errorMsg => $filesList) {
			$style->writeln(sprintf('%dx: %s',count($filesList) , $errorMsg));
			foreach ($filesList as $fileInfo) {
				// comment out this line to have a compact list of error types
				$style->writeln(sprintf(' - %s', $fileInfo));
			}
		}
		$style->note(sprintf($errorTypesCount === 1 ? 'Found %d error type' : 'Found %d error types', $errorTypesCount));
		$style->error(sprintf(
			$analysisResult->getTotalErrorsCount() === 1 ? 'Found %d error' : 'Found %d errors',
			$analysisResult->getTotalErrorsCount()
		));
		return 1;
	}
}

Quick and dirty fix for recent versions of phpstan (I have 0.12.43):

• Change use Symfony\Component\Console\Style\OutputStyle; to use PHPStan\Command\Output;
• Change all 5 occurrences of $style->*() to ->writeLineFormatted()

See phpstan/phpstan#1686 for some background info about all this