diff --git a/src/Analyser/MutatingScope.php b/src/Analyser/MutatingScope.php
index 22a895e03c..16a9c15f05 100644
--- a/src/Analyser/MutatingScope.php
+++ b/src/Analyser/MutatingScope.php
@@ -4379,6 +4379,17 @@ private function shouldInvalidateExpression(string $exprStringToInvalidate, Expr
 		$nodeFinder = new NodeFinder();
 		$expressionToInvalidateClass = get_class($exprToInvalidate);
 		$found = $nodeFinder->findFirst([$expr], function (Node $node) use ($expressionToInvalidateClass, $exprStringToInvalidate): bool {
+			if (
+				$exprStringToInvalidate === '$this'
+				&& $node instanceof Name
+				&& (
+					in_array($node->toLowerString(), ['self', 'static', 'parent'], true)
+					|| ($this->getClassReflection() !== null && $this->getClassReflection()->is($this->resolveName($node)))
+				)
+			) {
+				return true;
+			}
+
 			if (!$node instanceof $expressionToInvalidateClass) {
 				return false;
 			}
diff --git a/src/Analyser/NodeScopeResolver.php b/src/Analyser/NodeScopeResolver.php
index 756ea8db31..b43f0298cc 100644
--- a/src/Analyser/NodeScopeResolver.php
+++ b/src/Analyser/NodeScopeResolver.php
@@ -2597,6 +2597,13 @@ static function (): void {
 				$throwPoints[] = ThrowPoint::createImplicit($scope, $expr);
 			}
 
+			if (
+				$parametersAcceptor instanceof ClosureType && count($parametersAcceptor->getImpurePoints()) > 0
+				&& $scope->isInClass()
+			) {
+				$scope = $scope->invalidateExpression(new Variable('this'), true);
+			}
+
 			if (
 				$functionReflection !== null
 				&& in_array($functionReflection->getName(), ['json_encode', 'json_decode'], true)
@@ -3022,13 +3029,13 @@ static function (): void {
 
 			if (
 				$methodReflection !== null
-				&& !$methodReflection->isStatic()
 				&& (
 					$methodReflection->hasSideEffects()->yes()
-					|| $methodReflection->getName() === '__construct'
+					|| (
+						!$methodReflection->isStatic()
+						&& $methodReflection->getName() === '__construct'
+					)
 				)
-				&& $scopeFunction instanceof MethodReflection
-				&& !$scopeFunction->isStatic()
 				&& $scope->isInClass()
 				&& $scope->getClassReflection()->is($methodReflection->getDeclaringClass()->getName())
 			) {
diff --git a/tests/PHPStan/Analyser/nsrt/bug-12902-non-strict.php b/tests/PHPStan/Analyser/nsrt/bug-12902-non-strict.php
index d294016ec5..33f8a11e26 100644
--- a/tests/PHPStan/Analyser/nsrt/bug-12902-non-strict.php
+++ b/tests/PHPStan/Analyser/nsrt/bug-12902-non-strict.php
@@ -72,8 +72,8 @@ public function __construct()
 		assertNativeType('int', self::$i);
 
 		$this->impureCall();
-		assertType('int', self::$i); // should be float|int
-		assertNativeType('int', self::$i); // should be float|int
+		assertType('float|int', self::$i);
+		assertNativeType('float|int', self::$i);
 	}
 
 	public function doFoo(): void {
diff --git a/tests/PHPStan/Analyser/nsrt/bug-12902.php b/tests/PHPStan/Analyser/nsrt/bug-12902.php
index cbdc816074..2330c0c130 100644
--- a/tests/PHPStan/Analyser/nsrt/bug-12902.php
+++ b/tests/PHPStan/Analyser/nsrt/bug-12902.php
@@ -72,8 +72,8 @@ public function __construct()
 		assertNativeType('int', self::$i);
 
 		$this->impureCall();
-		assertType('int', self::$i); // should be float|int
-		assertNativeType('int', self::$i); // should be float|int
+		assertType('float|int', self::$i);
+		assertNativeType('float|int', self::$i);
 	}
 
 	public function doFoo(): void {
@@ -85,6 +85,33 @@ public function doFoo(): void {
 	public function impureCall(): void {}
 }
 
+class BaseClass
+{
+	static protected int|float $i;
+}
+
+class UsesBaseClass extends BaseClass
+{
+	public function __construct()
+	{
+		parent::$i = getInt();
+		assertType('int', parent::$i);
+		assertNativeType('int', parent::$i);
+
+		$this->impureCall();
+		assertType('float|int', parent::$i);
+		assertNativeType('float|int', parent::$i);
+	}
+
+	public function doFoo(): void {
+		assertType('float|int', parent::$i);
+		assertNativeType('float|int', parent::$i);
+	}
+
+	/** @phpstan-impure  */
+	public function impureCall(): void {}
+}
+
 function getInt(): int {
 	return 1;
 }
diff --git a/tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php b/tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php
index 0198587347..941829a685 100644
--- a/tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php
+++ b/tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php
@@ -930,4 +930,9 @@ public function testBug12593(): void
 		$this->analyse([__DIR__ . '/data/bug-12593.php'], []);
 	}
 
+	public function testBug3747(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-3747.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Arrays/data/bug-3747.php b/tests/PHPStan/Rules/Arrays/data/bug-3747.php
new file mode 100644
index 0000000000..d1dea20e05
--- /dev/null
+++ b/tests/PHPStan/Rules/Arrays/data/bug-3747.php
@@ -0,0 +1,27 @@
+<?php
+
+namespace Bug3747;
+
+class X {
+
+	/** @var array<string,string> $x */
+	private static array $x;
+
+	public function y(): void {
+
+		self::$x = [];
+
+		$this->z();
+
+		echo self::$x['foo'];
+
+	}
+
+	private function z(): void {
+		self::$x['foo'] = 'bar';
+	}
+
+}
+
+$x = new X();
+$x->y();
diff --git a/tests/PHPStan/Rules/Comparison/IfConstantConditionRuleTest.php b/tests/PHPStan/Rules/Comparison/IfConstantConditionRuleTest.php
index 1f03a122bd..25e362f6cc 100644
--- a/tests/PHPStan/Rules/Comparison/IfConstantConditionRuleTest.php
+++ b/tests/PHPStan/Rules/Comparison/IfConstantConditionRuleTest.php
@@ -173,4 +173,16 @@ public function testBug4912(): void
 		$this->analyse([__DIR__ . '/data/bug-4912.php'], []);
 	}
 
+	public function testBug4864(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-4864.php'], []);
+	}
+
+	public function testBug8926(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-8926.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php b/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
index 4c72f04c61..68cd2cc059 100644
--- a/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
+++ b/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
@@ -1011,4 +1011,9 @@ public function testBug12748(): void
 		$this->analyse([__DIR__ . '/data/bug-12748.php'], []);
 	}
 
+	public function testBug11019(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-11019.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Comparison/data/bug-11019.php b/tests/PHPStan/Rules/Comparison/data/bug-11019.php
new file mode 100644
index 0000000000..c6a64cec05
--- /dev/null
+++ b/tests/PHPStan/Rules/Comparison/data/bug-11019.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace Bug11019;
+
+class HelloWorld
+{
+	public static int $a;
+
+	public function reset(): void
+	{
+		static::$a = rand(1,10);
+	}
+
+	public function sayHello(): void
+	{
+		$this->reset();
+		assert(static::$a === 1);
+		$this->reset();
+		assert(static::$a === 1);
+	}
+}
diff --git a/tests/PHPStan/Rules/Comparison/data/bug-4864.php b/tests/PHPStan/Rules/Comparison/data/bug-4864.php
new file mode 100644
index 0000000000..288e19c21f
--- /dev/null
+++ b/tests/PHPStan/Rules/Comparison/data/bug-4864.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace Bug4864;
+
+class Example
+{
+	/** @var mixed */
+	private $value;
+	private bool $isHandled;
+
+	public function fetchValue(callable $f): void
+	{
+		$this->isHandled = false;
+		$this->value = null;
+
+		(function () {
+			$this->isHandled = true;
+			$this->value = 'value';
+		})();
+
+		if ($this->isHandled) {
+			$f($this->value);
+		}
+	}
+}
diff --git a/tests/PHPStan/Rules/Comparison/data/bug-8926.php b/tests/PHPStan/Rules/Comparison/data/bug-8926.php
new file mode 100644
index 0000000000..c5d92bd1e0
--- /dev/null
+++ b/tests/PHPStan/Rules/Comparison/data/bug-8926.php
@@ -0,0 +1,32 @@
+<?php
+
+namespace Bug8926;
+
+class Foo {
+	private bool $test;
+
+	/** @param int[] $arr */
+	function success(array $arr) : void {
+		$test = false;
+		(function($arr) use(&$test) {
+			$test = count($arr) == 1;
+		})($arr);
+
+		if ($test) {
+			echo "...\n";
+		}
+	}
+
+	/** @param int[] $arr */
+	function error(array $arr) : void {
+		$this->test = false;
+		(function($arr) {
+			$this->test = count($arr) == 1;
+		})($arr);
+
+
+		if ($this->test) {
+			echo "...\n";
+		}
+	}
+}
diff --git a/tests/PHPStan/Rules/Methods/NullsafeMethodCallRuleTest.php b/tests/PHPStan/Rules/Methods/NullsafeMethodCallRuleTest.php
index b954794c6e..5c308ea5ad 100644
--- a/tests/PHPStan/Rules/Methods/NullsafeMethodCallRuleTest.php
+++ b/tests/PHPStan/Rules/Methods/NullsafeMethodCallRuleTest.php
@@ -55,4 +55,19 @@ public function testBug6922b(): void
 		$this->analyse([__DIR__ . '/data/bug-6922b.php'], []);
 	}
 
+	public function testBug8523(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-8523.php'], []);
+	}
+
+	public function testBug8523b(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-8523b.php'], []);
+	}
+
+	public function testBug8523c(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-8523c.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php b/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
index 1c62efa0c0..bc3a1b1fae 100644
--- a/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
+++ b/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
@@ -1232,4 +1232,18 @@ public function testBug1O580(): void
 		]);
 	}
 
+	public function testBug4443(): void
+	{
+		if (PHP_VERSION_ID < 80000) {
+			$this->markTestSkipped('Test requires PHP 8.0.');
+		}
+
+		$this->analyse([__DIR__ . '/data/bug-4443.php'], [
+			[
+				'Method Bug4443\HelloWorld::getArray() should return array<mixed> but returns array<mixed>|null.',
+				22,
+			],
+		]);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Methods/data/bug-4443.php b/tests/PHPStan/Rules/Methods/data/bug-4443.php
new file mode 100644
index 0000000000..9f7ff6a28e
--- /dev/null
+++ b/tests/PHPStan/Rules/Methods/data/bug-4443.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace Bug4443;
+
+class HelloWorld
+{
+	/** @var array<mixed> */
+	private static ?array $arr = null;
+
+	private static function setup(): void
+	{
+		self::$arr = null;
+	}
+
+	/** @return array<mixed> */
+	public static function getArray(): array
+	{
+		if (self::$arr === null) {
+			self::$arr = [];
+			self::setup();
+		}
+		return self::$arr;
+	}
+}
+
+HelloWorld::getArray();
diff --git a/tests/PHPStan/Rules/Methods/data/bug-8523.php b/tests/PHPStan/Rules/Methods/data/bug-8523.php
new file mode 100644
index 0000000000..0cc8b3ad0a
--- /dev/null
+++ b/tests/PHPStan/Rules/Methods/data/bug-8523.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace Bug8523;
+
+class HelloWorld
+{
+	public static ?HelloWorld $instance = null;
+
+	public static function bazz(): void
+	{
+		self::$instance = null;
+	}
+
+	public function foo(): void
+	{
+		self::$instance = new HelloWorld();
+
+		self::bazz();
+
+		self::$instance?->foo();
+	}
+
+	public function bar(): void
+	{
+		self::$instance = null;
+	}
+
+	public function baz(): void
+	{
+		self::$instance = new HelloWorld();
+
+		$this->bar();
+
+		self::$instance?->foo();
+	}
+}
diff --git a/tests/PHPStan/Rules/Methods/data/bug-8523b.php b/tests/PHPStan/Rules/Methods/data/bug-8523b.php
new file mode 100644
index 0000000000..a007fd2661
--- /dev/null
+++ b/tests/PHPStan/Rules/Methods/data/bug-8523b.php
@@ -0,0 +1,24 @@
+<?php declare(strict_types = 1);
+
+namespace Bug8523b;
+
+class HelloWorld
+{
+	public static ?HelloWorld $instance = null;
+
+	public function save(): void {
+		self::$instance = new HelloWorld();
+
+		$callback = static function(): void {
+			self::$instance = null;
+		};
+
+		$callback();
+
+		var_dump(self::$instance);
+
+		self::$instance?->save();
+	}
+}
+
+(new HelloWorld())->save();
diff --git a/tests/PHPStan/Rules/Methods/data/bug-8523c.php b/tests/PHPStan/Rules/Methods/data/bug-8523c.php
new file mode 100644
index 0000000000..ea88940446
--- /dev/null
+++ b/tests/PHPStan/Rules/Methods/data/bug-8523c.php
@@ -0,0 +1,26 @@
+<?php declare(strict_types = 1);
+
+namespace Bug8523c;
+
+use function PHPStan\Testing\assertType;
+
+class HelloWorld
+{
+	public static ?HelloWorld $instance = null;
+
+	public function save(): void {
+        HelloWorld::$instance = new HelloWorld();
+
+		$callback = static function(): void {
+            HelloWorld::$instance = null;
+		};
+
+		$callback();
+
+		var_dump(HelloWorld::$instance);
+
+        HelloWorld::$instance?->save();
+	}
+}
+
+(new HelloWorld())->save();