bug: AlternativeSyntaxAnalyzer - fix for nested else

[jrmajor]

Fixes #6484.

[coveralls]

Coverage increased (+0.008%) to 92.897% when pulling 1ae8b3e on jrmajor:bugfix/bug-6484 into fab645b on FriendsOfPHP:master.

[SpacePossum]

Hi, thanks for this PR!

Maybe we can make the src/Tokenizer/Analyzer/AlternativeSyntaxAnalyzer.php::findAlternativeSyntaxBlockEnd a bit more easy to read now we indeed have to change it to fix the bug.
I was thinking something like:

    public function findAlternativeSyntaxBlockEnd(Tokens $tokens, int $index): int
    {
        if (!isset($tokens[$index])) {
            throw new \InvalidArgumentException("There is no token at index {$index}.");
        }

        if (!$this->isStartOfAlternativeSyntaxBlock($tokens, $index)) {
            throw new \InvalidArgumentException("Token at index {$index} is not the start of an alternative syntax block.");
        }

        $startTokenKind = $tokens[$index]->getId();
        $endTokenKinds = self::ALTERNATIVE_SYNTAX_BLOCK_EDGES[$startTokenKind];

        $findKinds = [[$startTokenKind]];
        foreach ($endTokenKinds as $endTokenKind) {
            $findKinds[] = [$endTokenKind];
        }

        while (true) {
            $index = $tokens->getNextTokenOfKind($index, $findKinds);

            if ($tokens[$index]->isGivenKind($endTokenKinds)) {
                return $index;
            }

            if ($this->isStartOfAlternativeSyntaxBlock($tokens, $index)) {
                $index = $this->findAlternativeSyntaxBlockEnd($tokens, $index);
            }
        }
    }

also, maybe we can update the signature:

private function isStartOfAlternativeSyntaxBlock(Tokens $tokens, $index): bool

into:

private function isStartOfAlternativeSyntaxBlock(Tokens $tokens, int $index): bool

[jrmajor]

@SpacePossum Thanks for the review, I appreciate your patience with my PRs! I've applied your suggestions and added you as co-author, as you've done most of the work there :)

[julienfalque]

Thank you @jrmajor.

[SpacePossum]

thanks @jrmajor , nice fix! :)