From fe77aec32180c8fb353dfafb8b6d43e886c5d823 Mon Sep 17 00:00:00 2001
From: HawkForge <75696486+HawkForge@users.noreply.github.com>
Date: Thu, 15 Oct 2026 17:30:55 +0600
Subject: [PATCH] Keep the failure value of filter_var() unless every PHP
 version has FILTER_THROW_ON_FAILURE

hasThrowOnFailureFlag() only returned no when none of the analysed PHP
versions has FILTER_THROW_ON_FAILURE. For a range like 8.4 - 8.5 it
checked the flag bit as if every version had it. Before PHP 8.5 that
bit (0x10000000) is FILTER_FLAG_GLOBAL_RANGE, so on PHP 8.4 a call with
FILTER_FLAG_GLOBAL_RANGE lost false from its return type and comparing
the result with false was reported as always true.

The flag result is now combined with the PHP version check, so it is
only yes when every analysed version throws instead of returning the
failure value.

Closes https://github.com/phpstan/phpstan/issues/15481
---
 .../Php/FilterFunctionReturnTypeHelper.php    | 10 ++++--
 tests/PHPStan/Analyser/Bug15481Test.php       | 36 +++++++++++++++++++
 tests/PHPStan/Analyser/bug-15481.neon         |  4 +++
 tests/PHPStan/Analyser/data/bug-15481.php     | 18 ++++++++++
 4 files changed, 65 insertions(+), 3 deletions(-)
 create mode 100644 tests/PHPStan/Analyser/Bug15481Test.php
 create mode 100644 tests/PHPStan/Analyser/bug-15481.neon
 create mode 100644 tests/PHPStan/Analyser/data/bug-15481.php

diff --git a/src/Type/Php/FilterFunctionReturnTypeHelper.php b/src/Type/Php/FilterFunctionReturnTypeHelper.php
index af128a42272..a36981b6d20 100644
--- a/src/Type/Php/FilterFunctionReturnTypeHelper.php
+++ b/src/Type/Php/FilterFunctionReturnTypeHelper.php
@@ -517,9 +517,13 @@ public function hasFlag(string $flagName, ?Type $flagsType): TrinaryLogic
 
 	private function hasThrowOnFailureFlag(?Type $flagsType, PhpVersions $phpVersions): TrinaryLogic
 	{
-		return $phpVersions->hasFilterThrowOnFailureConstant()->no()
-			? TrinaryLogic::createNo()
-			: $this->hasFlag('FILTER_THROW_ON_FAILURE', $flagsType);
+		$hasThrowOnFailureConstant = $phpVersions->hasFilterThrowOnFailureConstant();
+		if ($hasThrowOnFailureConstant->no()) {
+			return TrinaryLogic::createNo();
+		}
+
+		// before PHP 8.5, this bit is FILTER_FLAG_GLOBAL_RANGE and the failure value is still returned
+		return $hasThrowOnFailureConstant->and($this->hasFlag('FILTER_THROW_ON_FAILURE', $flagsType));
 	}
 
 	private function getFlagsValue(Type $exprType): Type
diff --git a/tests/PHPStan/Analyser/Bug15481Test.php b/tests/PHPStan/Analyser/Bug15481Test.php
new file mode 100644
index 00000000000..749636f3e05
--- /dev/null
+++ b/tests/PHPStan/Analyser/Bug15481Test.php
@@ -0,0 +1,36 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Analyser;
+
+use PHPStan\Testing\TypeInferenceTestCase;
+use PHPUnit\Framework\Attributes\DataProvider;
+
+class Bug15481Test extends TypeInferenceTestCase
+{
+
+	public static function dataFileAsserts(): iterable
+	{
+		yield from self::gatherAssertTypes(__DIR__ . '/data/bug-15481.php');
+	}
+
+	/**
+	 * @param mixed ...$args
+	 */
+	#[DataProvider('dataFileAsserts')]
+	public function testFileAsserts(
+		string $assertType,
+		string $file,
+		...$args,
+	): void
+	{
+		$this->assertFileAsserts($assertType, $file, ...$args);
+	}
+
+	public static function getAdditionalConfigFiles(): array
+	{
+		return [
+			__DIR__ . '/bug-15481.neon',
+		];
+	}
+
+}
diff --git a/tests/PHPStan/Analyser/bug-15481.neon b/tests/PHPStan/Analyser/bug-15481.neon
new file mode 100644
index 00000000000..43060cc0b5c
--- /dev/null
+++ b/tests/PHPStan/Analyser/bug-15481.neon
@@ -0,0 +1,4 @@
+parameters:
+	phpVersion:
+		min: 80400
+		max: 80599
diff --git a/tests/PHPStan/Analyser/data/bug-15481.php b/tests/PHPStan/Analyser/data/bug-15481.php
new file mode 100644
index 00000000000..26a6bb9bea7
--- /dev/null
+++ b/tests/PHPStan/Analyser/data/bug-15481.php
@@ -0,0 +1,18 @@
+<?php declare(strict_types = 1);
+
+namespace Bug15481;
+
+use function PHPStan\Testing\assertType;
+
+function isPublicAddress(string $address): bool
+{
+	assertType('non-falsy-string|false', filter_var($address, FILTER_VALIDATE_IP, FILTER_FLAG_GLOBAL_RANGE));
+	assertType('non-falsy-string|false', filter_var($address, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE | FILTER_FLAG_GLOBAL_RANGE));
+
+	return filter_var($address, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE | FILTER_FLAG_GLOBAL_RANGE) !== false;
+}
+
+function throwOnFailure(string $s): void
+{
+	assertType('int|false', filter_var($s, FILTER_VALIDATE_INT, FILTER_THROW_ON_FAILURE));
+}