The (void) cast is supported only on PHP 8.5 and later.

Author: ondrejmirtes

src/Php/PhpVersion.php

@@ -429,4 +429,9 @@ public function supportsFinalPromotedProperties(): bool
 		return $this->versionId >= 80500;
 	}
 
+	public function supportsVoidCast(): bool
+	{
+		return $this->versionId >= 80500;
+	}
+
 }

src/Rules/Cast/VoidCastRule.php

@@ -5,6 +5,7 @@
 use PhpParser\Node;
 use PHPStan\Analyser\Scope;
 use PHPStan\DependencyInjection\RegisteredRule;
+use PHPStan\Php\PhpVersion;
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleErrorBuilder;
 
@@ -15,7 +16,9 @@
 final class VoidCastRule implements Rule
 {
 
-	public function __construct()
+	public function __construct(
+		private PhpVersion $phpVersion,
+	)
 	{
 	}
 
@@ -26,16 +29,24 @@ public function getNodeType(): string
 
 	public function processNode(Node $node, Scope $scope): array
 	{
+		$errors = [];
+		if (!$this->phpVersion->supportsVoidCast()) {
+			$errors[] = RuleErrorBuilder::message('The (void) cast is supported only on PHP 8.5 and later.')
+				->identifier('cast.voidNotSupported')
+				->nonIgnorable()
+				->build();
+		}
+
 		if ($scope->isInFirstLevelStatement()) {
-			return [];
+			return $errors;
 		}
 
-		return [
-			RuleErrorBuilder::message('The (void) cast cannot be used within an expression.')
-				->identifier('cast.void')
-				->nonIgnorable()
-				->build(),
-		];
+		$errors[] = RuleErrorBuilder::message('The (void) cast cannot be used within an expression.')
+			->identifier('cast.void')
+			->nonIgnorable()
+			->build();
+
+		return $errors;
 	}
 
 }

tests/PHPStan/Rules/Cast/VoidCastRuleTest.php

@@ -2,8 +2,11 @@
 
 namespace PHPStan\Rules\Cast;
 
+use PHPStan\Php\PhpVersion;
 use PHPStan\Rules\Rule;
 use PHPStan\Testing\RuleTestCase;
+use PHPUnit\Framework\Attributes\RequiresPhp;
+use const PHP_VERSION_ID;
 
 /**
  * @extends RuleTestCase<VoidCastRule>
@@ -13,9 +16,10 @@ class VoidCastRuleTest extends RuleTestCase
 
 	protected function getRule(): Rule
 	{
-		return new VoidCastRule();
+		return new VoidCastRule(new PhpVersion(PHP_VERSION_ID));
 	}
 
+	#[RequiresPhp('>= 8.5')]
 	public function testPrintRule(): void
 	{
 		$this->analyse([__DIR__ . '/data/void-cast.php'], [
@@ -34,4 +38,18 @@ public function testPrintRule(): void
 		]);
 	}
 
+	public function testSupport(): void
+	{
+		$errors = [];
+		if (PHP_VERSION_ID < 80500) {
+			$errors = [
+				[
+					'The (void) cast is supported only on PHP 8.5 and later.',
+					10,
+				],
+			];
+		}
+		$this->analyse([__DIR__ . '/data/void-cast-support.php'], $errors);
+	}
+
 }

tests/PHPStan/Rules/Cast/data/void-cast-support.php

@@ -0,0 +1,13 @@
+<?php // lint >= 8.5
+
+namespace VoidCastSupport;
+
+class Foo
+{
+
+	public function doFoo(): void
+	{
+		(void) 1;
+	}
+
+}