Incorrect @var PDOStatement<int,string> contains unresolvable type

Bug report

When using a PDOStatement with mode PDO::FETCH_COLUMN I want to be able to type the statement with the appropriate type for the column, e.g. @var PDOStatement<int,string>.

For PHPStan versions up to 2.1.38, this works correctly and no errors are reported. From PHPStan 2.1.39 onwards, this now reports:

PHPDoc tag @var contains unresolvable type.
🪪  varTag.unresolvableType

Code snippet that reproduces the problem

https://phpstan.org/r/0122fc0d-29d4-4aa1-8a57-480dc399d1de

Expected output

No errors found.

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PHPStan is fantastic at helping me find bugs before they even get committed and pushing me in the direction of writing better code.

PDOStatement does not seems to be a generic
https://github.com/phpstan/phpstan-src/blob/ed40e65342856506cbc5e99bccb5853b941169a9/stubs/PDOStatement.stub#L8

So PDOStatement<int,string> does not make sens currently. (and shouldn't work before even if it was not reported)

You could try https://github.com/staabm/phpstan-dba which will infer the types based on db schema

Same issue here: https://phpstan.org/r/c085525e-890d-4fc5-b6fd-6df79a8dea72
This used to work at least in version 2.1.32

My quick and dirty solution for my issue is to revert the change that was made in the stubs-file in version 2.1.39

$phar = new Phar('phpstan.phar');
$phar->addFromString('stubs/PDOStatement.stub', str_replace('@return Iterator<mixed, array<int|string, mixed>>', '@return Iterator', $phar['stubs/PDOStatement.stub']->getContent()));

@MacGritsch

the simplified example from @MacGritsch regressed in 2.1.39 with

97288da8e82cf4d507a60edf93b2d60a0ab5ec72 is the first bad commit
commit 97288da8e82cf4d507a60edf93b2d60a0ab5ec72 (HEAD)
Author: Daniel Fahlke <flyingmana@googlemail.com>
Date:   Wed Feb 11 09:29:26 2026 +0100

    Bleeding edge - Require generics for Iterator, IteratorAggregate, Generator

 conf/bleedingEdge.neon                                                     |  1 +
 conf/config.neon                                                           |  1 +
 conf/parametersSchema.neon                                                 |  1 +
 src/Rules/MissingTypehintCheck.php                                         | 10 +++++++++-
 stubs/PDOStatement.stub                                                    |  2 +-
 stubs/runtime/ReflectionAttribute.php                                      |  3 +++
 tests/PHPStan/Analyser/nsrt/bug-8886.php                                   |  2 +-
 tests/PHPStan/Rules/Classes/LocalTypeAliasesRuleTest.php                   |  2 +-
 tests/PHPStan/Rules/Classes/LocalTypeTraitAliasesRuleTest.php              |  2 +-
 tests/PHPStan/Rules/Classes/LocalTypeTraitUseAliasesRuleTest.php           |  2 +-
 tests/PHPStan/Rules/Classes/MethodTagRuleTest.php                          |  2 +-
 tests/PHPStan/Rules/Classes/MethodTagTraitRuleTest.php                     |  2 +-
 tests/PHPStan/Rules/Classes/MethodTagTraitUseRuleTest.php                  |  2 +-
 tests/PHPStan/Rules/Classes/MixinRuleTest.php                              |  6 +++++-
 tests/PHPStan/Rules/Classes/MixinTraitRuleTest.php                         |  2 +-
 tests/PHPStan/Rules/Classes/MixinTraitUseRuleTest.php                      |  2 +-
 tests/PHPStan/Rules/Classes/PropertyTagRuleTest.php                        |  2 +-
 tests/PHPStan/Rules/Classes/PropertyTagTraitRuleTest.php                   |  2 +-
 tests/PHPStan/Rules/Classes/PropertyTagTraitUseRuleTest.php                |  2 +-
 tests/PHPStan/Rules/Constants/MissingClassConstantTypehintRuleTest.php     |  2 +-
 tests/PHPStan/Rules/Functions/MissingFunctionParameterTypehintRuleTest.php |  2 +-
 tests/PHPStan/Rules/Functions/MissingFunctionReturnTypehintRuleTest.php    | 23 ++++++++++++++++++++++-
 tests/PHPStan/Rules/Functions/data/missing-function-return-typehint.php    | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/PHPStan/Rules/Methods/MissingMethodParameterTypehintRuleTest.php     |  2 +-
 tests/PHPStan/Rules/Methods/MissingMethodReturnTypehintRuleTest.php        |  7 ++++++-
 tests/PHPStan/Rules/Methods/MissingMethodSelfOutTypeRuleTest.php           |  2 +-
 tests/PHPStan/Rules/Methods/data/missing-method-return-typehint.php        |  2 +-
 tests/PHPStan/Rules/PhpDoc/FunctionAssertRuleTest.php                      |  2 +-
 tests/PHPStan/Rules/PhpDoc/InvalidPhpDocVarTagTypeRuleTest.php             |  2 +-
 tests/PHPStan/Rules/PhpDoc/MethodAssertRuleTest.php                        |  2 +-
 tests/PHPStan/Rules/Properties/MissingPropertyTypehintRuleTest.php         |  2 +-
 tests/PHPStan/Rules/Properties/SetPropertyHookParameterRuleTest.php        |  2 +-
 32 files changed, 144 insertions(+), 27 deletions(-)

@var

Fix phpstan/phpstan#14206: @var PDOStatement<int,string> incorrectly …

@staabm

Looking at the bot explanation, I understand more the issue now.

Something like PDOStatement<int,array<string>> works fine, the issue is related to PDOStatement<int,string> because
the template of PDOStatement is defined

 * @implements Traversable<array<int|string, mixed>>
 * @implements IteratorAggregate<array<int|string, mixed>>

with getIterator returning Iterator<mixed, array<int|string, mixed>>

I'm not familiar with PDO Statement. But from my unstanding we'll have

PDOStatement<int, string>   // with FETCH_COLUMN
PDOStatement<int, array>    // with FETCH_ASSOC (défaut)
PDOStatement<int, object>   // with FETCH_OBJ

So it shouldn't be

Traversable<array<int|string, mixed>>

but

Traversable<scalar|array|object|null>

and we should just simplify to Traversable<mixed>

Best would be having the type restricted thanks to setFetchMode ; maybe with
https://phpstan.org/writing-php-code/phpdocs-basics#change-type-of-current-object-after-calling-a-method

Until now

/**
 * @implements Traversable<mixed>
 * @implements IteratorAggregate<mixed>
 */
class PDOStatement implements Traversable, IteratorAggregate
{
    /**
     * @return Iterator<mixed>
     */
    public function getIterator() {}
}

Could work (?) WDYT @staabm

staabm/phpstan-dba would resolve the given example

class Test
{
	public function test(PDO $db): void
	{
		$statement = $db->prepare('SELECT foo FROM bar');
		$statement->setFetchMode(PDO::FETCH_COLUMN, 0);
		$statement->execute();
	}
}

and make the types aware to PHPStan without the need for additional inline @vars.

my feeling is in phpstan-src core we should use dumb-down types which are generic enough to support all possible use-cases.
since the most php database APIs (like PDO, mysqli, mysql,..) are stateful, its really hard to mirror them - the types depend on the used database backend, the global configuration of PDO etc (e.g. there is a global fetch mode).
thats why phpstan-dba exists in the first place.

I think we should strip down the builtin stub as much as necessary so it works with all relevant use-cases out of the box and tell people to use phpstan-dba when they want more magic/precise types out of the box.

Closed via merging phpstan/phpstan-src#5132

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.

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Incorrect `@var PDOStatement<int,string>` contains unresolvable type #14206

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Incorrect @var PDOStatement<int,string> contains unresolvable type #14206

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VincentLanglet commented on Feb 26, 2026

staabm commented on Feb 26, 2026

MacGritsch commented on Mar 3, 2026

MacGritsch commented on Mar 3, 2026

staabm commented on Mar 4, 2026

VincentLanglet commented on Mar 4, 2026

staabm commented on Mar 4, 2026

phpstan-bot commented on Mar 6, 2026

github-actions commented on Apr 7, 2026

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Incorrect `@var PDOStatement<int,string>` contains unresolvable type #14206