Fix generated fast path bypassing global TransformerRegistry casters

[dereuromark]

AbstractDto::fromArray() guarded the generated fast path with HAS_FAST_PATH only, while __construct() and _toArrayInternal() additionally checked the TransformerRegistry. Casters are consumed in the generic setFromArray() path, so a globally registered caster was silently skipped when hydrating a generated DTO through fromArray(), even though new Dto($data) applied it.

TransformerRegistry::addCaster(PlainClass::class, fn ($v) => new PlainClass('cast:' . $v));

new GeneratedDto(['plainData' => 'hello']);                 // cast:hello
(new GeneratedDto())->fromArray(['plainData' => 'hello']);  // hello   <- wrong

While fixing this, the guards are also scoped to the direction they actually apply to:

• input (constructor, fromArray()) bypasses the fast path only when a caster is registered
• output (toArray()) bypasses it only when a serializer is registered

Previously any registration disabled both, so registering an output-only serializer forced generic hydration - an unnecessary slowdown, and a behavior change for DTOs with lazy fields, which would then hydrate eagerly.

TransformerRegistry::hasAnyCaster() and hasAnySerializer() are added for this; hasAny() stays as is.

The regression was untestable with the existing fixtures because they are all non-fast-path, so tests/TestDto/FastPathCasterDto.php mimics generated output for a class-typed field.

[Copilot]

Pull request overview

This PR fixes a correctness issue where generated DTOs using the hydration fast path (HAS_FAST_PATH) could bypass globally registered casters when calling AbstractDto::fromArray(). It also refines the fast-path guard conditions so that fast paths are bypassed only in the relevant direction: casters disable fast-path hydration, while serializers disable fast-path serialization.

Changes:

• Add TransformerRegistry::hasAnyCaster() and TransformerRegistry::hasAnySerializer() to distinguish input vs output transformer registrations.
• Update Dto::__construct(), AbstractDto::fromArray(), and Dto::_toArrayInternal() to use the new direction-specific guards.
• Add a fast-path-like test DTO plus new tests to cover caster/serializer interactions with generated fast paths.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/TestDto/FastPathCasterDto.php	Adds a test DTO that mimics generated fast-path behavior for a class-typed field.
tests/Dto/DtoTest.php	Adds regression tests ensuring global casters/serializers interact correctly with fast-path DTO hydration/serialization.
src/Transformer/TransformerRegistry.php	Adds hasAnyCaster() / hasAnySerializer() helpers while keeping hasAny() intact.
src/Dto/Dto.php	Switches fast-path guards: constructor checks casters; _toArrayInternal() checks serializers.
src/Dto/AbstractDto.php	Ensures fromArray() fast path is only taken when no global casters are registered.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.27%. Comparing base (de2306c) to head (333ca69).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #114      +/-   ##
============================================
+ Coverage     83.07%   83.27%   +0.19%     
- Complexity     1555     1558       +3     
============================================
  Files            45       45              
  Lines          3835     3839       +4     
============================================
+ Hits           3186     3197      +11     
+ Misses          649      642       -7     

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