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Fix phpstan/phpstan#9732: BenevolentUnionType with generics produce confusing errors #5070

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Fix phpstan/phpstan#9732: BenevolentUnionType with generics produce confusing errors #5070

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43dc704
Fix BenevolentUnionType with generics producing false positive errors
github-actions[bot] Feb 27, 2026
2f36068
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VincentLanglet Feb 28, 2026
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18 changes: 18 additions & 0 deletions src/Type/Generic/TemplateTypeTrait.php
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
use PHPStan\Type\TypeUtils;
use PHPStan\Type\UnionType;
use PHPStan\Type\VerbosityLevel;
use function count;
use function sprintf;

/**
Expand Down Expand Up @@ -287,6 +288,23 @@ public function inferTemplateTypes(Type $receivedType): TemplateTypeMap
]))->union($map);
}

if ($receivedType instanceof UnionType) {
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@staabm staabm Feb 28, 2026

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can we drop the previous if on line 285 than? seems like its redundant now?

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@VincentLanglet VincentLanglet Feb 28, 2026

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It's not redundant, the previous if will works

  • For any non UnionType
  • For BenevolentUnionType
  • For UnionType in which the whole type is superTypeOf

$matchingTypes = [];
foreach ($receivedType->getTypes() as $innerType) {
if (!$resolvedBound->isSuperTypeOf($innerType)->yes()) {
continue;
}

$matchingTypes[] = $innerType;
}
if (count($matchingTypes) > 0) {
$filteredType = TypeCombinator::union(...$matchingTypes);
return (new TemplateTypeMap([
$this->name => $filteredType,
]))->union($map);
}
}

return $map;
}

Expand Down
14 changes: 14 additions & 0 deletions tests/PHPStan/Rules/Methods/CallStaticMethodsRuleTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -931,6 +931,20 @@ public function testBug13556(): void
$this->analyse([__DIR__ . '/data/bug-13556.php'], []);
}

public function testBug9732(): void
{
$this->checkThisOnly = false;
$this->checkExplicitMixed = true;
$this->checkImplicitMixed = true;

$this->analyse([__DIR__ . '/data/bug-9732.php'], [
[
'Parameter #1 $array of static method Bug9732\HelloWorld::stringifyKeys() expects array<string, mixed>, array<mixed> given.',
21,
],
]);
}

#[RequiresPhp('>= 8.5')]
public function testPipeOperator(): void
{
Expand Down
23 changes: 23 additions & 0 deletions tests/PHPStan/Rules/Methods/data/bug-9732.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,23 @@
<?php declare(strict_types = 1);

namespace Bug9732;

class HelloWorld
{
/**
* @phpstan-template TKeyType of string
* @phpstan-template TValueType
* @phpstan-param array<TKeyType, TValueType> $array
* @phpstan-return \Generator<TKeyType, TValueType, void, void>
*/
public static function stringifyKeys(array $array) : \Generator{
foreach($array as $key => $value){
yield (string) $key => $value;
}
}

public function sayHello(): void
{
self::stringifyKeys($GLOBALS);
}
}
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