Add test for isset in methods called from constructor

Tests that isset() on properties without defaults in methods called
from the constructor does not produce false positives, while isset()
on properties with defaults or in non-constructor-called methods
still correctly reports errors.

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

Author: phpstan-bot

tests/PHPStan/Rules/Variables/IssetRuleTest.php

@@ -543,6 +543,26 @@ public function testBug13473(): void
 		]);
 	}
 
+	public function testIssetMethodCalledFromConstructor(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+
+		$this->analyse([__DIR__ . '/data/isset-method-called-from-constructor.php'], [
+			[
+				'Property IssetMethodCalledFromConstructor\MethodCalledFromConstructorWithDefault::$bar in isset() is not nullable nor uninitialized.',
+				34,
+			],
+			[
+				'Property IssetMethodCalledFromConstructor\MethodNotCalledFromConstructor::$bar in isset() is not nullable nor uninitialized.',
+				51,
+			],
+			[
+				'Property IssetMethodCalledFromConstructor\MultipleProperties::$bar in isset() is not nullable nor uninitialized.',
+				72,
+			],
+		]);
+	}
+
 	public function testBug14393(): void
 	{
 		$this->treatPhpDocTypesAsCertain = true;

tests/PHPStan/Rules/Variables/data/isset-method-called-from-constructor.php

@@ -0,0 +1,77 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace IssetMethodCalledFromConstructor;
+
+final class MethodCalledFromConstructor {
+	private int $bar;
+
+	public function __construct(int $bar)
+	{
+		$this->setBar($bar);
+	}
+
+	private function setBar(int $bar): void
+	{
+		if (isset($this->bar)) { // $bar has no default, could be uninitialized when called from constructor - no error
+			throw new \Exception('bar is set');
+		}
+		$this->bar = $bar;
+	}
+}
+
+final class MethodCalledFromConstructorWithDefault {
+	private int $bar = 1;
+
+	public function __construct(int $bar)
+	{
+		$this->setBar($bar);
+	}
+
+	private function setBar(int $bar): void
+	{
+		if (isset($this->bar)) { // $bar has default value, always initialized - should error
+			throw new \Exception('bar is set');
+		}
+		$this->bar = $bar;
+	}
+}
+
+final class MethodNotCalledFromConstructor {
+	private int $bar;
+
+	public function __construct(int $bar)
+	{
+		$this->bar = $bar;
+	}
+
+	private function checkBar(): void
+	{
+		if (isset($this->bar)) { // Not called from constructor, property is initialized after construction - should error
+			echo 'bar is set';
+		}
+	}
+}
+
+final class MultipleProperties {
+	private int $foo;
+	private int $bar = 5;
+
+	public function __construct(int $bar)
+	{
+		$this->init($bar);
+		$this->foo = 42;
+	}
+
+	private function init(int $bar): void
+	{
+		if (isset($this->foo)) { // $foo has no default, could be uninitialized - no error
+			throw new \Exception('foo is set');
+		}
+		if (isset($this->bar)) { // $bar has default value, always initialized - should error
+			echo 'bar is set';
+		}
+		$this->bar = $bar;
+	}
+}