Fixed regression from commit 9665e16

src/Analyser/MutatingScope.php

@@ -2574,15 +2574,14 @@ public function assignExpression(Expr $expr, Type $type): self
 		return $scope->specifyExpressionType($expr, $type);
 	}
 
-	public function invalidateExpression(Expr $expressionToInvalidate): self
+	public function invalidateExpression(Expr $expressionToInvalidate, bool $requireMoreCharacters = false): self
 	{
 		$exprStringToInvalidate = $this->printer->prettyPrintExpr($expressionToInvalidate);
 		$moreSpecificTypeHolders = $this->moreSpecificTypes;
 		foreach (array_keys($moreSpecificTypeHolders) as $exprString) {
 			$exprString = (string) $exprString;
 			if (Strings::startsWith($exprString, $exprStringToInvalidate)) {
-				if ($exprString === $exprStringToInvalidate) {
-					unset($moreSpecificTypeHolders[$exprString]);
+				if ($exprString === $exprStringToInvalidate && $requireMoreCharacters) {
 					continue;
 				}
 				$nextLetter = substr($exprString, strlen($exprStringToInvalidate), 1);

src/Analyser/NodeScopeResolver.php

@@ -1492,7 +1492,7 @@ function (MutatingScope $scope) use ($expr, $nodeCallback, $context): Expression
 			$result = $this->processArgs($methodReflection, $parametersAcceptor, $expr->args, $scope, $nodeCallback, $context);
 			$scope = $result->getScope();
 			if ($methodReflection !== null && $methodReflection->hasSideEffects()->yes()) {
-				$scope = $scope->invalidateExpression($expr->var);
+				$scope = $scope->invalidateExpression($expr->var, true);
 			}
 			$hasYield = $hasYield || $result->hasYield();
 		} elseif ($expr instanceof StaticCall) {

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -9772,6 +9772,11 @@ public function dataBug2750(): array
 		return $this->gatherAssertTypes(__DIR__ . '/data/bug-2750.php');
 	}
 
+	public function dataBug2850(): array
+	{
+		return $this->gatherAssertTypes(__DIR__ . '/data/bug-2850.php');
+	}
+
 	/**
 	 * @dataProvider dataBug2574
 	 * @dataProvider dataBug2577
@@ -9799,6 +9804,7 @@ public function dataBug2750(): array
 	 * @dataProvider dataBug2835
 	 * @dataProvider dataBug2443
 	 * @dataProvider dataBug2750
+	 * @dataProvider dataBug2850
 	 * @param ConstantStringType $expectedType
 	 * @param Type $actualType
 	 */

tests/PHPStan/Analyser/data/bug-2850.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace Bug2850;
+
+use function PHPStan\Analyser\assertType;
+
+class Foo
+{
+	public function y(): void {}
+}
+
+class Bar
+{
+	/** @var Foo|null */
+	private $x;
+
+	public function getFoo(): Foo
+	{
+		if ($this->x === null) {
+			$this->x = new Foo();
+			assertType(Foo::class, $this->x);
+			$this->x->y();
+			assertType(Foo::class, $this->x);
+			$this->y();
+			assertType(Foo::class . '|null', $this->x);
+		}
+		return $this->x;
+	}
+
+	public function y(): void
+	{
+		$this->x = null;
+	}
+}