Also detect static $this as fatal error

Add ThisInStaticStatementRule to report "Cannot use $this as static variable."
alongside the existing global $this and catch $this checks.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

src/Rules/Variables/ThisInStaticStatementRule.php

@@ -0,0 +1,44 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Variables;
+
+use PhpParser\Node;
+use PHPStan\Analyser\Scope;
+use PHPStan\DependencyInjection\RegisteredRule;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+use function is_string;
+
+/**
+ * @implements Rule<Node\Stmt\Static_>
+ */
+#[RegisteredRule(level: 0)]
+final class ThisInStaticStatementRule implements Rule
+{
+
+	public function getNodeType(): string
+	{
+		return Node\Stmt\Static_::class;
+	}
+
+	public function processNode(Node $node, Scope $scope): array
+	{
+		$errors = [];
+		foreach ($node->vars as $var) {
+			if (!is_string($var->var->name)) {
+				continue;
+			}
+			if ($var->var->name !== 'this') {
+				continue;
+			}
+
+			$errors[] = RuleErrorBuilder::message('Cannot use $this as static variable.')
+				->identifier('static.this')
+				->nonIgnorable()
+				->build();
+		}
+
+		return $errors;
+	}
+
+}

tests/PHPStan/Rules/Variables/ThisInStaticStatementRuleTest.php

@@ -0,0 +1,29 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Variables;
+
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+
+/**
+ * @extends RuleTestCase<ThisInStaticStatementRule>
+ */
+class ThisInStaticStatementRuleTest extends RuleTestCase
+{
+
+	protected function getRule(): Rule
+	{
+		return new ThisInStaticStatementRule();
+	}
+
+	public function testBug14351(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-14351.php'], [
+			[
+				'Cannot use $this as static variable.',
+				19,
+			],
+		]);
+	}
+
+}

tests/PHPStan/Rules/Variables/data/bug-14351.php

@@ -14,3 +14,7 @@ function foo(): void {
 function foo(): void {
 	global $this; // should report: Cannot use $this as global variable
 }
+
+function bar(): void {
+	static $this; // should report: Cannot use $this as static variable
+}