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add array_first and array_last return type extensions #4499

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Merged
merged 3 commits into from
Oct 31, 2025
Merged

add array_first and array_last return type extensions #4499

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4e29e4e
add array_first and array_last return type extensions
canvural Oct 30, 2025
73651b5
use getIterableValueType
canvural Oct 31, 2025
5f3237a
deprecate getFirstIterable*Type and getLastIterable*Type methods
canvural Oct 31, 2025
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48 changes: 48 additions & 0 deletions src/Type/Php/ArrayFirstDynamicReturnTypeExtension.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,48 @@
<?php declare(strict_types = 1);

namespace PHPStan\Type\Php;

use PhpParser\Node\Expr\FuncCall;
use PHPStan\Analyser\Scope;
use PHPStan\DependencyInjection\AutowiredService;
use PHPStan\Reflection\FunctionReflection;
use PHPStan\Type\DynamicFunctionReturnTypeExtension;
use PHPStan\Type\NullType;
use PHPStan\Type\Type;
use PHPStan\Type\TypeCombinator;
use function count;

#[AutowiredService]
final class ArrayFirstDynamicReturnTypeExtension implements DynamicFunctionReturnTypeExtension
{

public function isFunctionSupported(FunctionReflection $functionReflection): bool
{
return $functionReflection->getName() === 'array_first' && $functionReflection->isBuiltin();
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@canvural canvural Oct 30, 2025

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Not sure if this is the correct way. Maybe we can check the PHP version. Because I thought there might be userland functions named array_first that would also be processed here.

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@ondrejmirtes ondrejmirtes Oct 31, 2025

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I think it's okay like this, we don't check this anywhere for similar extensions. As a benefit it'd also work for polyfills running on lower PHP versions.

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@canvural canvural Oct 31, 2025

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So should I remove the $functionReflection->isBuiltin() part?

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@ondrejmirtes ondrejmirtes Oct 31, 2025

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Yes 😊

}

public function getTypeFromFunctionCall(FunctionReflection $functionReflection, FuncCall $functionCall, Scope $scope): ?Type
{
$args = $functionCall->getArgs();

if (count($args) < 1) {
return null;
}

$argType = $scope->getType($args[0]->value);
$iterableAtLeastOnce = $argType->isIterableAtLeastOnce();

if ($iterableAtLeastOnce->no()) {
return new NullType();
}

$valueType = $argType->getFirstIterableValueType();
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@ondrejmirtes ondrejmirtes Oct 31, 2025

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When I thought about the implementation, I'd do only getIterableValueType. The getFirstIterable*Type methods are highly misleading and we should get rid of it. Because array shapes do not enforce the order of the keys. Sorry to put more burden on you, but can you please deprecate Type::getFirstIterableKeyType, getLastIterableKeyType, getFirstIterableValueType, getLastIterableValueType and use getIterableKeyType and getIterableValueType in all places instead? And just update any test assertions because of that. Thank you!

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@canvural canvural Oct 31, 2025

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Alright. I can do that. But we will lose the precise type for constant arrays that way.

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@ondrejmirtes ondrejmirtes Oct 31, 2025

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Yeah, that's okay. Ideally we would have two separate implementations for literal arrays and PHPDoc array shapes but we don't.

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@canvural canvural Oct 31, 2025

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Done with 73651b5 and 5f3237a

I didn't really check the assertions, just fixed whatever PHPStan said.


if ($iterableAtLeastOnce->yes()) {
return $valueType;
}

return TypeCombinator::union($valueType, new NullType());
}

}
48 changes: 48 additions & 0 deletions src/Type/Php/ArrayLastDynamicReturnTypeExtension.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,48 @@
<?php declare(strict_types = 1);

namespace PHPStan\Type\Php;

use PhpParser\Node\Expr\FuncCall;
use PHPStan\Analyser\Scope;
use PHPStan\DependencyInjection\AutowiredService;
use PHPStan\Reflection\FunctionReflection;
use PHPStan\Type\DynamicFunctionReturnTypeExtension;
use PHPStan\Type\NullType;
use PHPStan\Type\Type;
use PHPStan\Type\TypeCombinator;
use function count;

#[AutowiredService]
final class ArrayLastDynamicReturnTypeExtension implements DynamicFunctionReturnTypeExtension
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@staabm staabm Oct 31, 2025

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as this 2 extensions are very similar, you might consider using a single extension class for handling both

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@canvural canvural Oct 31, 2025

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With the recent refactoring they are now merged into one

{

public function isFunctionSupported(FunctionReflection $functionReflection): bool
{
return $functionReflection->getName() === 'array_last' && $functionReflection->isBuiltin();
}

public function getTypeFromFunctionCall(FunctionReflection $functionReflection, FuncCall $functionCall, Scope $scope): ?Type
{
$args = $functionCall->getArgs();

if (count($args) < 1) {
return null;
}

$argType = $scope->getType($args[0]->value);
$iterableAtLeastOnce = $argType->isIterableAtLeastOnce();

if ($iterableAtLeastOnce->no()) {
return new NullType();
}

$valueType = $argType->getLastIterableValueType();

if ($iterableAtLeastOnce->yes()) {
return $valueType;
}

return TypeCombinator::union($valueType, new NullType());
}

}
22 changes: 22 additions & 0 deletions tests/PHPStan/Analyser/nsrt/array_first_last.php
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<?php // lint >= 8.5

namespace ArrayFirstLast;

use function PHPStan\Testing\assertType;

/**
* @param string[] $stringArray
* @param non-empty-array<int, string> $nonEmptyArray
*/
function doFoo(array $stringArray, array $nonEmptyArray, $mixed): void
{
assertType("'a'", array_first([1 => 'a', 0 => 'b', 2 => 'c']));
assertType('string|null', array_first($stringArray));
assertType('string', array_first($nonEmptyArray));
assertType('mixed', array_first($mixed));

assertType("'c'", array_last([1 => 'a', 0 => 'b', 2 => 'c']));
assertType('string|null', array_last($stringArray));
assertType('string', array_last($nonEmptyArray));
assertType('mixed', array_last($mixed));
}
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