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Fix phpstan/phpstan#14394: NAN ==/=== anything is always evaluated as false #5332

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Fix phpstan/phpstan#14394: NAN ==/=== anything is always evaluated as false #5332

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869b3e4
Fix phpstan/phpstan#14394: NAN ==/=== anything is always evaluated as…
VincentLanglet Mar 29, 2026
b5638cc
Fix containsNan to handle union array types and optional keys
phpstan-bot Mar 29, 2026
f0cb81a
Simplify containsNan: remove isConstantArray check and inline constan…
phpstan-bot Mar 29, 2026
2302b10
Fix NAN same-variable comparison: $a === $a where $a is NAN should be…
phpstan-bot Mar 29, 2026
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26 changes: 26 additions & 0 deletions src/Reflection/InitializerExprTypeResolver.php
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Original file line number Diff line number Diff line change
Expand Up @@ -114,6 +114,7 @@
use function is_finite;
use function is_float;
use function is_int;
use function is_nan;
use function is_numeric;
use function is_string;
use function max;
Expand Down Expand Up @@ -1944,6 +1945,10 @@ public function resolveIdenticalType(Type $leftType, Type $rightType): TypeResul
return new TypeResult(new ConstantBooleanType(false), []);
}

if ($this->containsNan($leftType) || $this->containsNan($rightType)) {
return new TypeResult(new ConstantBooleanType(false), []);
}

if ($leftType instanceof ConstantScalarType && $rightType instanceof ConstantScalarType) {
return new TypeResult(new ConstantBooleanType($leftType->getValue() === $rightType->getValue()), []);
}
Expand Down Expand Up @@ -1972,6 +1977,10 @@ public function resolveIdenticalType(Type $leftType, Type $rightType): TypeResul
*/
public function resolveEqualType(Type $leftType, Type $rightType): TypeResult
{
if ($this->containsNan($leftType) || $this->containsNan($rightType)) {
return new TypeResult(new ConstantBooleanType(false), []);
}

if (
($leftType->isEnum()->yes() && $rightType->isTrue()->no())
|| ($rightType->isEnum()->yes() && $leftType->isTrue()->no())
Expand Down Expand Up @@ -2061,6 +2070,23 @@ private function resolveConstantArrayTypeComparison(ConstantArrayType $leftType,
return new TypeResult($resultType->toBoolean(), []);
}

private function containsNan(Type $type): bool
{
if ($type instanceof ConstantFloatType && is_nan($type->getValue())) {
return true;
}

foreach ($type->getConstantArrays() as $constantArray) {
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@VincentLanglet VincentLanglet Mar 29, 2026

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If the array is array{Nan}|array{1} the egality check might be true.

We need all array to contain Nan on a non optional

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@phpstan-bot phpstan-bot Mar 29, 2026

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All done — both background tasks (make tests and make phpstan) completed successfully, and the fix has been pushed.

foreach ($constantArray->getValueTypes() as $valueType) {
if ($this->containsNan($valueType)) {
return true;
}
}
}

return false;
}

/**
* @param BinaryOp\Plus|BinaryOp\Minus|BinaryOp\Mul|BinaryOp\Div|BinaryOp\ShiftLeft|BinaryOp\ShiftRight $expr
*/
Expand Down
15 changes: 15 additions & 0 deletions tests/PHPStan/Rules/Comparison/ConstantLooseComparisonRuleTest.php
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Expand Up @@ -248,4 +248,19 @@ public function testBug13098(): void
$this->analyse([__DIR__ . '/data/bug-13098.php'], []);
}

public function testBug14394(): void
{
$this->treatPhpDocTypesAsCertain = true;
$this->analyse([__DIR__ . '/data/bug-14394.php'], [
[
'Loose comparison using == between float and NAN will always evaluate to false.',
8,
],
[
'Loose comparison using == between list<mixed> and array{NAN} will always evaluate to false.',
10,
],
]);
}

}
26 changes: 26 additions & 0 deletions tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -1164,11 +1164,37 @@ public function testPossiblyImpureTip(): void
public function testBug11054(): void
{
$this->analyse([__DIR__ . '/data/bug-11054.php'], [
[
'Strict comparison using === between mixed and array{NAN} will always evaluate to false.',
24,
],
[
'Strict comparison using === between mixed and array{NAN} will always evaluate to false.',
28,
],
[
'Strict comparison using === between mixed and array{INF} will always evaluate to false.',
47,
'Type array{INF} has already been eliminated from mixed.',
],
[
'Strict comparison using === between mixed and array{NAN} will always evaluate to false.',
55,
],
]);
}

public function testBug14394(): void
{
$this->analyse([__DIR__ . '/data/bug-14394.php'], [
[
'Strict comparison using === between float and NAN will always evaluate to false.',
9,
],
[
'Strict comparison using === between list<mixed> and array{NAN} will always evaluate to false.',
11,
],
]);
}

Expand Down
13 changes: 13 additions & 0 deletions tests/PHPStan/Rules/Comparison/data/bug-14394.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,13 @@
<?php declare(strict_types = 1);

namespace Bug14394;

class Cl {
/** @param list<mixed> $v2 */
public static function test(float $v1, array $v2): void {
if ($v1 == NAN) { echo "never reached\n"; }
if ($v1 === NAN) { echo "never reached\n"; }
if ($v2 == [NAN]) { echo "never reached\n"; }
if ($v2 === [NAN]) { echo "never reached\n"; }
}
}
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