Make ConstantArrayTypeBuilder::ARRAY_COUNT_LIMIT configurable

[gnutix]

🤖 Generated by Claude Code

Fixes phpstan/phpstan#8636 (which has happened on our project too)

Summary

• Add new configuration parameter constantArrayTypeBuilderArrayCountLimit that allows users to customize the array count limit
• Default value remains 256 (current behavior)
• Follow the existing BleedingEdgeToggle pattern with a static accessor class
• Keep the original constant for backward compatibility (marked as deprecated)

Usage

Users can configure the limit in their phpstan.neon:

parameters:
    constantArrayTypeBuilderArrayCountLimit: 512

Test plan

• Unit tests pass: vendor/bin/phpunit tests/PHPStan/Type/Constant/ConstantArrayTypeBuilderTest.php (7 tests, 41 assertions)
• Syntax validation: All modified files pass php -l syntax check
• Manual verification with test script demonstrating the feature:

<?php
use PHPStan\DependencyInjection\ConstantArrayTypeLimitAccessor;
use PHPStan\Type\Constant\ConstantArrayTypeBuilder;
use PHPStan\Type\Constant\ConstantStringType;

// Build array with 300 elements
$builder = ConstantArrayTypeBuilder::createEmpty();
for ($i = 0; $i < 300; $i++) {
    $builder->setOffsetValueType(new ConstantStringType("key_$i"), new ConstantStringType("value_$i"));
}

// With default limit (256): array is degraded
$type = $builder->getArray();
// Result: PHPStan\Type\IntersectionType (degraded)

// With increased limit (512): array is tracked precisely
ConstantArrayTypeLimitAccessor::setLimit(512);
$builder2 = ConstantArrayTypeBuilder::createEmpty();
for ($i = 0; $i < 300; $i++) {
    $builder2->setOffsetValueType(new ConstantStringType("key_$i"), new ConstantStringType("value_$i"));
}
$type2 = $builder2->getArray();
// Result: PHPStan\Type\Constant\ConstantArrayType with 300 keys (precise)

Test results:

Array Size	Limit	Result
200	256	✓ Precise (ConstantArrayType)
300	256	✗ Degraded (IntersectionType)
300	512	✓ Precise (ConstantArrayType)
600	512	✗ Degraded (IntersectionType)

[staabm]

you should measure the perf impact when using different values for this limit, as it could get very slow depending on your code

[ondrejmirtes]

Hi, I disagree with this solution. I don't want to let people shoot themselves in the foot by slowing down PHPStan.

The right solution to this problem is to improve ConstantArrayType performance so we can raise the limit.

If you have some examples where the current limit limits you, please open issues about them and we'll try to make the limit higher by making PHPStan faster.