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Fix phpstan/phpstan#14201: List union: identify list types when checking its first element #5249

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Fix phpstan/phpstan#14201: List union: identify list types when checking its first element #5249

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9655055
Fix phpstan/phpstan#14201: Narrow array type when element from reset/…
phpstan-bot Mar 19, 2026
dc0c8b3
Add test cases with array<Foo|Bar> annotation
phpstan-bot Mar 19, 2026
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74 changes: 74 additions & 0 deletions src/Analyser/ExprHandler/AssignHandler.php
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,7 @@
use PHPStan\Type\Accessory\AccessoryArrayListType;
use PHPStan\Type\Accessory\HasOffsetValueType;
use PHPStan\Type\Accessory\NonEmptyArrayType;
use PHPStan\Type\ArrayType;
use PHPStan\Type\Constant\ConstantArrayType;
use PHPStan\Type\Constant\ConstantIntegerType;
use PHPStan\Type\Constant\ConstantStringType;
Expand All @@ -60,6 +61,7 @@
use PHPStan\Type\Type;
use PHPStan\Type\TypeCombinator;
use PHPStan\Type\TypeUtils;
use PHPStan\Type\UnionType;
use TypeError;
use function array_key_last;
use function array_merge;
Expand Down Expand Up @@ -281,6 +283,13 @@
$conditionalExpressions = $this->processSureNotTypesForConditionalExpressionsAfterAssign($scope, $var->name, $conditionalExpressions, $identicalSpecifiedTypes, $falseyType);
}

$conditionalExpressions = $this->processArrayValueExtractionForConditionalExpressions(
$scope,
$var->name,
$conditionalExpressions,
$assignedExpr,
);

$nodeScopeResolver->callNodeCallback($nodeCallback, new VariableAssignNode($var, $assignedExpr), $scopeBeforeAssignEval, $storage);
$scope = $scope->assignVariable($var->name, $type, $scope->getNativeType($assignedExpr), TrinaryLogic::createYes());
foreach ($conditionalExpressions as $exprString => $holders) {
Expand Down Expand Up @@ -1076,4 +1085,69 @@
return false;
}

/**
* @param array<string, ConditionalExpressionHolder[]> $conditionalExpressions
* @return array<string, ConditionalExpressionHolder[]>
*/
private function processArrayValueExtractionForConditionalExpressions(
Scope $scope,
string $variableName,
array $conditionalExpressions,
Expr $assignedExpr,
): array
{
if (
!$assignedExpr instanceof Expr\FuncCall
|| !$assignedExpr->name instanceof Name
|| !in_array($assignedExpr->name->toLowerString(), ['reset', 'current', 'end'], true)
|| count($assignedExpr->getArgs()) < 1
) {
return $conditionalExpressions;
}

$arrayArg = $assignedExpr->getArgs()[0]->value;
if (!$arrayArg instanceof Variable || !is_string($arrayArg->name)) {
return $conditionalExpressions;
}

$arrayArgType = $scope->getType($arrayArg);
if (!$arrayArgType->isArray()->yes()) {

Check warning on line 1114 in src/Analyser/ExprHandler/AssignHandler.php

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GitHub Actions / Mutation Testing (8.4, ubuntu-latest) 

Escaped Mutant for Mutator "PHPStan\Infection\TrinaryLogicMutator":

@@ @@
 		}
 
 		$arrayArgType = $scope->getType($arrayArg);
-		if (!$arrayArgType->isArray()->yes()) {
+		if ($arrayArgType->isArray()->no()) {
 			return $conditionalExpressions;
 		}

Check warning on line 1114 in src/Analyser/ExprHandler/AssignHandler.php

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GitHub Actions / Mutation Testing (8.3, ubuntu-latest) 

Escaped Mutant for Mutator "PHPStan\Infection\TrinaryLogicMutator":

@@ @@
 		}
 
 		$arrayArgType = $scope->getType($arrayArg);
-		if (!$arrayArgType->isArray()->yes()) {
+		if ($arrayArgType->isArray()->no()) {
 			return $conditionalExpressions;
 		}
return $conditionalExpressions;
}

$valueType = $arrayArgType->getIterableValueType();
if (!$valueType instanceof UnionType) {
return $conditionalExpressions;
}

$valueTypeMembers = $valueType->getTypes();
if (count($valueTypeMembers) < 2) {
return $conditionalExpressions;
}

$arrayExprString = '$' . $arrayArg->name;
$keyType = $arrayArgType->getIterableKeyType();

foreach ($valueTypeMembers as $memberType) {
$narrowedArrayType = TypeCombinator::intersect(
$arrayArgType,
new ArrayType($keyType, $memberType),
);

$holder = new ConditionalExpressionHolder(
['$' . $variableName => ExpressionTypeHolder::createYes(
new Variable($variableName),
$memberType,
)],
ExpressionTypeHolder::createYes(
$arrayArg,
$narrowedArrayType,
),
);
$conditionalExpressions[$arrayExprString][$holder->getKey()] = $holder;
}

return $conditionalExpressions;
}

}
101 changes: 101 additions & 0 deletions tests/PHPStan/Analyser/nsrt/bug-14201.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,101 @@
<?php // lint >= 8.0

declare(strict_types = 1);

namespace Bug14201;

use function PHPStan\Testing\assertType;

class Foo { public function __construct(public string $fooName) {}}
class Bar { public function __construct(public string $barName) {}}

class HelloWorld
{
/**
* @param Foo[]|Bar[] $items
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@staabm staabm Mar 19, 2026

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We need another test with array<Foo|Bar>

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@phpstan-bot phpstan-bot Mar 19, 2026

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Already confirmed — both PHPStan and tests passed. The commit with the array<Foo|Bar> test cases has been pushed.

*/
public function doitMatch(array $items): void
{
if ([] === $items) {return; }

$first = reset($items);
match (true) {
$first instanceOf Foo => array_map(function ($i) {
assertType('Bug14201\Foo', $i);
return $i->fooName;
}, $items),
$first instanceOf Bar => array_map(function ($i) {
assertType('Bug14201\Bar', $i);
return $i->barName;
}, $items),
default => throw new \RuntimeException('None of Foo nor Bar')
};
}

/**
* @param Foo[]|Bar[] $items
*/
public function doitIf(array $items): void
{
if ([] === $items) {return; }

$first = reset($items);
if ($first instanceof Foo) {
assertType('non-empty-array<Bug14201\Foo>', $items);
array_map(function ($i) {
assertType('Bug14201\Foo', $i);
return $i->fooName;
}, $items);
} elseif ($first instanceof Bar) {
assertType('non-empty-array<Bug14201\Bar>', $items);
array_map(function ($i) {
assertType('Bug14201\Bar', $i);
return $i->barName;
}, $items);
}
}

/**
* @param array<Foo|Bar> $items
*/
public function doitMatchArrayUnion(array $items): void
{
if ([] === $items) {return; }

$first = reset($items);
match (true) {
$first instanceOf Foo => array_map(function ($i) {
assertType('Bug14201\Foo', $i);
return $i->fooName;
}, $items),
$first instanceOf Bar => array_map(function ($i) {
assertType('Bug14201\Bar', $i);
return $i->barName;
}, $items),
default => throw new \RuntimeException('None of Foo nor Bar')
};
}

/**
* @param array<Foo|Bar> $items
*/
public function doitIfArrayUnion(array $items): void
{
if ([] === $items) {return; }

$first = reset($items);
if ($first instanceof Foo) {
assertType('non-empty-array<Bug14201\Foo>', $items);
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@staabm staabm Mar 20, 2026

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this is wrong

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@phpstan-bot phpstan-bot Mar 20, 2026

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I processed this review but have nothing to report.

array_map(function ($i) {
assertType('Bug14201\Foo', $i);
return $i->fooName;
}, $items);
} elseif ($first instanceof Bar) {
assertType('non-empty-array<Bug14201\Bar>', $items);
array_map(function ($i) {
assertType('Bug14201\Bar', $i);
return $i->barName;
}, $items);
}
}
}
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