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Fix subtype check for identical late-resolvable conditional types (bug #10942)#4579

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yt-catpaw wants to merge 3 commits intophpstan:2.1.xfrom
yt-catpaw:fix-contravariant-param-10942
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Fix subtype check for identical late-resolvable conditional types (bug #10942)#4579
yt-catpaw wants to merge 3 commits intophpstan:2.1.xfrom
yt-catpaw:fix-contravariant-param-10942

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@yt-catpaw yt-catpaw commented Nov 26, 2025

closes phpstan/phpstan#10942

・Summary

Treat identical late-resolvable conditional types as compatible before resolving them.
Short-circuit when the same conditional appears inside a union.
Add regression test for bug #10942.

・Testing

vendor/bin/phpunit tests/PHPStan/Rules/Methods/MethodSignatureRuleTest.php --filter testBug10942

ondrejmirtes
ondrejmirtes requested changes Nov 26, 2025
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src/Type/Traits/LateResolvableTypeTrait.php

public function isSubTypeOf(Type $otherType): IsSuperTypeOfResult
{
if ($this->equals($otherType)) {
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@ondrejmirtes ondrejmirtes Nov 26, 2025

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It'd make sense to write some tests that test this method directly. Similar to this:

phpstan-src/tests/PHPStan/Type/UnionTypeTest.php

Lines 174 to 473 in 43e8099

/**
* @return Iterator<array-key, array{UnionType, Type, TrinaryLogic}>
*/
public static function dataIsSuperTypeOf(): Iterator
{
$int = new IntegerType();
$string = new StringType();
$unionTypeA = new UnionType([
$int,
$string,
]);
yield [
$unionTypeA,
$int,
TrinaryLogic::createYes(),
];
yield [
$unionTypeA,
$string,
TrinaryLogic::createYes(),
];
yield [
$unionTypeA,
$unionTypeA,
TrinaryLogic::createYes(),
];
yield [
$unionTypeA,
new IntersectionType([new StringType(), new CallableType()]),
TrinaryLogic::createYes(),
];
yield [
$unionTypeA,
new MixedType(),
TrinaryLogic::createMaybe(),
];
yield [
$unionTypeA,
new CallableType(),
TrinaryLogic::createMaybe(),
];
yield [
$unionTypeA,
new UnionType([new IntegerType(), new FloatType()]),
TrinaryLogic::createMaybe(),
];
yield [
$unionTypeA,
new UnionType([new CallableType(), new FloatType()]),
TrinaryLogic::createMaybe(),
];
yield [
$unionTypeA,
new IntersectionType([new MixedType(), new CallableType()]),
TrinaryLogic::createMaybe(),
];
yield [
$unionTypeA,
new FloatType(),
TrinaryLogic::createNo(),
];
yield [
$unionTypeA,
new UnionType([new ConstantBooleanType(true), new FloatType()]),
TrinaryLogic::createNo(),
];
yield [
$unionTypeA,
new IterableType(new MixedType(), new MixedType()),
TrinaryLogic::createNo(),
];
yield [
$unionTypeA,
new IntersectionType([new ArrayType(new MixedType(), new MixedType()), new CallableType()]),
TrinaryLogic::createNo(),
];
$intersectionTypeB = new IntersectionType([
new ObjectType('ArrayObject'),
new IterableType(new MixedType(), new ObjectType('DatePeriod')),
]);
$arrayTypeB = new ArrayType(new MixedType(), new ObjectType('DatePeriod'));
$unionTypeB = new UnionType([
$intersectionTypeB,
$arrayTypeB,
]);
yield [
$unionTypeB,
$intersectionTypeB,
TrinaryLogic::createYes(),
];
yield [
$unionTypeB,
$arrayTypeB,
TrinaryLogic::createYes(),
];
yield [
$unionTypeB,
$unionTypeB,
TrinaryLogic::createYes(),
];
yield [
$unionTypeB,
new MixedType(),
TrinaryLogic::createMaybe(),
];
yield [
$unionTypeB,
new ObjectType('ArrayObject'),
TrinaryLogic::createMaybe(),
];
yield [
$unionTypeB,
new IterableType(new MixedType(), new ObjectType('DatePeriod')),
TrinaryLogic::createMaybe(),
];
yield [
$unionTypeB,
new IterableType(new MixedType(), new MixedType()),
TrinaryLogic::createMaybe(),
];
yield [
$unionTypeB,
new StringType(),
TrinaryLogic::createNo(),
];
yield [
$unionTypeB,
new IntegerType(),
TrinaryLogic::createNo(),
];
yield [
$unionTypeB,
new ObjectType(stdClass::class),
TrinaryLogic::createNo(),
];
yield [
$unionTypeB,
new IterableType(new MixedType(), new ObjectType('DateTime')),
TrinaryLogic::createNo(),
];
yield [
$unionTypeB,
new CallableType(),
TrinaryLogic::createMaybe(),
];
yield [
$unionTypeB,
new IntersectionType([new MixedType(), new CallableType()]),
TrinaryLogic::createMaybe(),
];
yield [
$unionTypeB,
new IntersectionType([new StringType(), new CallableType()]),
TrinaryLogic::createNo(),
];
yield 'is super type of template-of-union with same members' => [
new UnionType([
new IntegerType(),
new FloatType(),
]),
TemplateTypeFactory::create(
TemplateTypeScope::createWithClass('Foo'),
'T',
new UnionType([
new IntegerType(),
new FloatType(),
]),
TemplateTypeVariance::createInvariant(),
),
TrinaryLogic::createYes(),
];
yield 'is super type of template-of-union equal to a union member' => [
new UnionType([
TemplateTypeFactory::create(
TemplateTypeScope::createWithClass('Foo'),
'T',
new UnionType([
new IntegerType(),
new FloatType(),
]),
TemplateTypeVariance::createInvariant(),
),
new NullType(),
]),
TemplateTypeFactory::create(
TemplateTypeScope::createWithClass('Foo'),
'T',
new UnionType([
new IntegerType(),
new FloatType(),
]),
TemplateTypeVariance::createInvariant(),
),
TrinaryLogic::createYes(),
];
yield 'maybe super type of template-of-union equal to a union member' => [
new UnionType([
TemplateTypeFactory::create(
TemplateTypeScope::createWithClass('Foo'),
'T',
new UnionType([
new IntegerType(),
new FloatType(),
]),
TemplateTypeVariance::createInvariant(),
),
new NullType(),
]),
TemplateTypeFactory::create(
TemplateTypeScope::createWithClass('Bar'),
'T',
new UnionType([
new IntegerType(),
new FloatType(),
]),
TemplateTypeVariance::createInvariant(),
),
TrinaryLogic::createMaybe(),
];
yield 'is super type of template-of-string equal to a union member' => [
new UnionType([
TemplateTypeFactory::create(
TemplateTypeScope::createWithClass('Foo'),
'T',
new StringType(),
TemplateTypeVariance::createInvariant(),
),
new NullType(),
]),
TemplateTypeFactory::create(
TemplateTypeScope::createWithClass('Foo'),
'T',
new StringType(),
TemplateTypeVariance::createInvariant(),
),
TrinaryLogic::createYes(),
];
yield 'maybe super type of template-of-string sub type of a union member' => [
new UnionType([
TemplateTypeFactory::create(
TemplateTypeScope::createWithClass('Foo'),
'T',
new StringType(),
TemplateTypeVariance::createInvariant(),
),
new NullType(),
]),
TemplateTypeFactory::create(
TemplateTypeScope::createWithClass('Bar'),
'T',
new StringType(),
TemplateTypeVariance::createInvariant(),
),
TrinaryLogic::createMaybe(),
];
}
#[DataProvider('dataIsSuperTypeOf')]
public function testIsSuperTypeOf(UnionType $type, Type $otherType, TrinaryLogic $expectedResult): void
{
$actualResult = $type->isSuperTypeOf($otherType);
$this->assertSame(
$expectedResult->describe(),
$actualResult->describe(),
sprintf('%s -> isSuperTypeOf(%s)', $type->describe(VerbosityLevel::precise()), $otherType->describe(VerbosityLevel::precise())),
);
}

Also, please review and maybe fix the isSuperTypeOf method as well.

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@yt-catpaw yt-catpaw Nov 27, 2025

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Implemented; please take a look

0ba6805

ondrejmirtes
ondrejmirtes requested changes Nov 27, 2025
View reviewed changes
tests/PHPStan/Type/LateResolvableTypeTraitTest.php Outdated
$conditional,
]);

$this->assertSame('Yes', $conditional->isSuperTypeOf($unionWithConditional)->describe());
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@ondrejmirtes ondrejmirtes Nov 27, 2025

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Please make a test with a data provider as it looks like in the test I linked. Then I'l try to come up with some data points that break your logic 😊

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@ondrejmirtes ondrejmirtes Nov 27, 2025

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Also write tests for both isSuperTypeOf and isSubtypeOf. Thanks!

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@yt-catpaw yt-catpaw Nov 27, 2025

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28bd4ec

Added data-provider tests for isSuperTypeOf/isSubTypeOf (in tests/PHPStan/Type/LateResolvableTypeTraitTest.php).

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Successfully merging this pull request may close these issues.

Wrong Parameter #3 $x ... of method B::foo() should be contravariant with parameter $x ... of method A::foo()

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