Callable signature compatibility in PHPDoc

Group: Callables · Category: language · File: callables_docblock_signature.php

References: - PHPStan callable type syntax - Psalm callable type syntax

Analyzer results

Analyzer	Version	Result	Diagnostics
phan	6.0.7Phan 6.0.7 php-ast version 1.1.3 PHP version used to run Phan: 8.5.9	Pass	callables_docblock_signature.php:27: Argument 1 ($callback) is (fn) of type Closure(string):string but \Conformance\Tests\CallablesDocblockSignature\takesIntToStringCallable() takes callable(int):string defined at /Users/megurine/repo/php/php-typing-conformance/conformance/tests/callables_docblock_signature.php:18 (expected type to be the same or a subtype, but saw a supertype instead) [PhanTypeMismatchArgumentSuperType]
phpstan	2.2.8PHPStan - PHP Static Analysis Tool 2.2.8	Pass reported Lv.5+	callables_docblock_signature.php:27: Parameter #1 $callback of function Conformance\Tests\CallablesDocblockSignature\takesIntToStringCallable expects callable(int): string, Closure(string): string given. [identifier=argument.type] [reported-from-level=5] With strict-rules callables_docblock_signature.php:27: Parameter #1 $callback of function Conformance\Tests\CallablesDocblockSignature\takesIntToStringCallable expects callable(int): string, Closure(string): string given. [identifier=argument.type]
psalm	6.16.1Psalm 6.16.1@f1f5de594dc76faf8784e02d3dc4716c91c6f6ac next: 7.0.0-beta19	Pass	callables_docblock_signature.php:27: Argument 1 of Conformance\Tests\CallablesDocblockSignature\takesIntToStringCallable expects callable(int):string, but pure-Closure(string):string provided [InvalidScalarArgument]
mago	1.46.0mago 1.46.0	Pass	callables_docblock_signature.php:27: Invalid argument type for argument #1 of `Conformance\Tests\CallablesDocblockSignature\takesIntToStringCallable`: expected `(callable(int): string)`, but found `(closure(string): string)`. [invalid-argument]
mir	0.70.1mir 0.70.1	Pass	callables_docblock_signature.php:27: InvalidArgument: Argument $callback of takesIntToStringCallable() expects 'callable whose parameter #1 accepts int', got 'callable whose parameter #1 only accepts string' [MIR0201]
phpantom	0.9.0phpantom_lsp 0.9.0	Fail	No diagnostics reported. Expectation diff Line 27: Expected 1 error(s)
intelephense	1.18.5intelephense 1.18.5	Fail	No diagnostics reported. Expectation diff Line 27: Expected 1 error(s)
phpy	0.2.0phpy 0.2.0	Fail	No diagnostics reported. Expectation diff Line 27: Expected 1 error(s)
qodana	262.8665.325Qodana 262.8665.325	Fail	No diagnostics reported. Expectation diff Line 27: Expected 1 error(s)
noverify	0.5.5NoVerify, version 0.5.5: built on: 2025.04.22 14:36:46 OS: r-kuchinskas arm64 Commit: 4774b82f8adc53fbef38f95e97af4b953b4d1529	Fail	No diagnostics reported. Expectation diff Line 27: Expected 1 error(s)
steins	0.1.5steins 0.1.5 (2026-08-12 revision 39b4cc1)	Pass	callables_docblock_signature.php:27: callable argument to takesIntToStringCallable() violates declared @param callable(int): string $callback — parameter #1 type is incompatible (callable parameter contravariance) [phpdoc.param-mismatch]
phpstan-strict	2.2.8PHPStan - PHP Static Analysis Tool 2.2.8	Pass	callables_docblock_signature.php:27: Parameter #1 $callback of function Conformance\Tests\CallablesDocblockSignature\takesIntToStringCallable expects callable(int): string, Closure(string): string given. [identifier=argument.type]
psalm-next	7.0.0-beta19Psalm 7.0.0-beta19@7e751c06a756fa64dc4c759c09fe4a173afcb433	Pass	callables_docblock_signature.php:27: Argument 1 of Conformance\Tests\CallablesDocblockSignature\takesIntToStringCallable expects impure-callable(int):string, but pure-Closure(string):string provided [InvalidScalarArgument]

Source

<?php

declare(strict_types=1);

namespace Conformance\Tests\CallablesDocblockSignature;

/**
 * Callable signature compatibility in PHPDoc.
 *
 * References:
 * - PHPStan callable type syntax
 * - Psalm callable type syntax
 */

/**
 * @param callable(int): string $callback
 */
function takesIntToStringCallable(callable $callback): void
{
}

takesIntToStringCallable(
    static fn (int $value): string => (string) $value,
);

takesIntToStringCallable(
    static fn (string $value): string => $value, // E: callable parameter type is incompatible
);