Fix containsNull() for union with (null&T of mixed)

Author: vojtech-dobes

phpstan-baseline.neon

@@ -1653,7 +1653,7 @@ parameters:
 		-
 			rawMessage: 'Doing instanceof PHPStan\Type\NullType is error-prone and deprecated. Use Type::isNull() instead.'
 			identifier: phpstanApi.instanceofType
-			count: 2
+			count: 1
 			path: src/Type/TypeCombinator.php
 
 		-

src/Type/TypeCombinator.php

@@ -175,7 +175,7 @@ public static function containsNull(Type $type): bool
 	{
 		if ($type instanceof UnionType) {
 			foreach ($type->getTypes() as $innerType) {
-				if ($innerType instanceof NullType) {
+				if ($innerType->isNull()->yes()) {
 					return true;
 				}
 			}

tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php

@@ -1873,6 +1873,15 @@ public function testNullSafe(): void
 		]);
 	}
 
+	public function testNullSafeOnTemplateTypeNarrowedAgainstNull(): void
+	{
+		$this->checkThisOnly = false;
+		$this->checkNullables = true;
+		$this->checkUnionTypes = true;
+
+		$this->analyse([__DIR__ . '/data/nullsafe-method-call-template-type.php'], []);
+	}
+
 	#[RequiresPhp('< 8.0.0')]
 	public function testDisallowNamedArguments(): void
 	{

tests/PHPStan/Rules/Methods/data/nullsafe-method-call-template-type.php

@@ -0,0 +1,26 @@
+<?php // lint >= 8.0
+
+namespace NullsafeMethodCallTemplateType;
+
+class Foo
+{
+
+	public function getValue(): ?string
+	{
+		return null;
+	}
+
+}
+
+/**
+ * @template T
+ * @param T $foo
+ */
+function foo($foo)
+{
+	if ($foo !== null && !$foo instanceof Foo) {
+		throw new \Exception();
+	}
+
+	return $foo?->getValue();
+}