@psalm-assert !Type@psalm-assert int $value (which *adds* a type), the
! prefix *subtracts* one. Starting from int|string, after the call
$value is known to be string. Tools that parse !int as an unknown
type name (or ignore the tag) leave the union alone.
Note: probing mixed with is_int() after !int is a weak signal —
Psalm does not treat mixed \ int as "is_int always false". A union with
a concrete alternative is the documented shape that surfaces subtraction.
References:
- Psalm assertion_syntax.md: Negated assertions
- Psalm adding_assertions.md: @psalm-assert !null $value
- PHPStan narrowing-types.md: Type negation (!string)| 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 | Not enforced | No diagnostics reported.
|
| phpstan | 2.2.8PHPStan - PHP Static Analysis Tool 2.2.8 | Not enforced reported Lv.4+ | phpdoc_advanced_vendor_prefixed_assert_negated_psalm.php:43: Call to function is_int() with string will always evaluate to false. [identifier=function.impossibleType] [reported-from-level=4] With strict-rulesphpdoc_advanced_vendor_prefixed_assert_negated_psalm.php:43: Call to function is_int() with string will always evaluate to false. [identifier=function.impossibleType]
Expectation diffLine 43: Expected valid value to be accepted, got ["Call to function is_int() with string will always evaluate to false. [identifier=function.impossibleType] [reported-from-level=4]"] |
| psalm | 6.16.1Psalm 6.16.1@f1f5de594dc76faf8784e02d3dc4716c91c6f6ac next: 7.0.0-beta19 |
Not enforced (pzoom≠) | phpdoc_advanced_vendor_prefixed_assert_negated_psalm.php:43: Docblock-defined type string for $value is never int [DocblockTypeContradiction] phpdoc_advanced_vendor_prefixed_assert_negated_psalm.php:43: Docblock-defined type string for $value is never int [RedundantConditionGivenDocblockType] pzoom (Psalm port)No diagnostics from pzoom.
Expectation diffLine 43: Expected valid value to be accepted, got ["Docblock-defined type string for $value is never int [DocblockTypeContradiction]","Docblock-defined type string for $value is never int [RedundantConditionGivenDocblockType]"] |
| mago | 1.46.0mago 1.46.0 | Not enforced | phpdoc_advanced_vendor_prefixed_assert_negated_psalm.php:43: Impossible type assertion: `$value` of type `string` can never be `int`. [impossible-type-comparison] phpdoc_advanced_vendor_prefixed_assert_negated_psalm.php:43: Redundant ternary operator: condition is always falsy. [impossible-condition]
Expectation diffLine 43: Expected valid value to be accepted, got ["Impossible type assertion: `$value` of type `string` can never be `int`. [impossible-type-comparison]","Redundant ternary operator: condition is always falsy. [impossible-condition]"] |
| mir | 0.70.1mir 0.70.1 | Not enforced | No diagnostics reported.
|
| phpantom | 0.9.0phpantom_lsp 0.9.0 | Not enforced | No diagnostics reported.
|
| intelephense | 1.18.5intelephense 1.18.5 | Not enforced | No diagnostics reported.
|
| phpy | 0.2.0phpy 0.2.0 | Not enforced | No diagnostics reported.
|
| qodana | 262.8665.325Qodana 262.8665.325 | Not enforced | No diagnostics reported.
|
| noverify | 0.5.5NoVerify, version 0.5.5: built on: 2025.04.22 14:36:46 OS: r-kuchinskas arm64 Commit: 4774b82f8adc53fbef38f95e97af4b953b4d1529 | Not enforced | No diagnostics reported.
|
| steins | 0.1.5steins 0.1.5 (2026-08-12 revision 39b4cc1) | Not enforced | No diagnostics reported.
|
| phpstan-strict | 2.2.8PHPStan - PHP Static Analysis Tool 2.2.8 | Not enforced | phpdoc_advanced_vendor_prefixed_assert_negated_psalm.php:43: Call to function is_int() with string will always evaluate to false. [identifier=function.impossibleType]
Expectation diffLine 43: Expected valid value to be accepted, got ["Call to function is_int() with string will always evaluate to false. [identifier=function.impossibleType]"] |
| psalm-next | 7.0.0-beta19Psalm 7.0.0-beta19@7e751c06a756fa64dc4c759c09fe4a173afcb433 | Not enforced | phpdoc_advanced_vendor_prefixed_assert_negated_psalm.php:43: Docblock-defined type string for $value is never int [DocblockTypeContradiction] phpdoc_advanced_vendor_prefixed_assert_negated_psalm.php:43: Docblock-defined type string for $value is never int [RedundantConditionGivenDocblockType]
Expectation diffLine 43: Expected valid value to be accepted, got ["Docblock-defined type string for $value is never int [DocblockTypeContradiction]","Docblock-defined type string for $value is never int [RedundantConditionGivenDocblockType]"] |
<?php
declare(strict_types=1);
namespace Conformance\Tests\PhpdocAdvancedVendorPrefixedAssertNegatedPsalm;
/**
* Negated assertion form `@psalm-assert !Type`.
*
* Unlike a positive `@psalm-assert int $value` (which *adds* a type), the
* `!` prefix *subtracts* one. Starting from `int|string`, after the call
* `$value` is known to be `string`. Tools that parse `!int` as an unknown
* type name (or ignore the tag) leave the union alone.
*
* Note: probing `mixed` with `is_int()` after `!int` is a weak signal —
* Psalm does not treat `mixed \ int` as "is_int always false". A union with
* a concrete alternative is the documented shape that surfaces subtraction.
*
* References:
* - Psalm assertion_syntax.md: Negated assertions
* - Psalm adding_assertions.md: `@psalm-assert !null $value`
* - PHPStan narrowing-types.md: Type negation (`!string`)
*/
/**
* @psalm-assert !int $value
*/
function assertNotInt(int|string $value): void // T: @psalm-assert !int
{
if (\is_int($value)) {
throw new \InvalidArgumentException('must not be int');
}
}
function takesString(string $value): void
{
}
function example(int|string $value): void
{
assertNotInt($value);
takesString($value); // V
// After subtracting int, only string remains, so an is_int() check is
// provably dead. A tool that parses `!int` as an unknown type name (or
// ignores the tag) leaves the union intact, where is_int() is a live check
// and nothing is reported — so the diagnostic marks real enforcement.
echo \is_int($value) ? 'int' : 'string'; // E?: after @psalm-assert !int, is_int() is always false
}