From 5a565a2d3c774716a6a85edab84c85bc337f62ec Mon Sep 17 00:00:00 2001
From: Markus Staab <maggus.staab@googlemail.com>
Date: Sun, 27 Oct 2024 08:56:05 +0100
Subject: [PATCH] Fix signature type for default-null parameters

---
 .../SignatureMap/Php8SignatureMapProvider.php   | 17 ++++++++++++++++-
 .../CallToFunctionParametersRuleTest.php        |  6 ++++++
 tests/PHPStan/Rules/Functions/data/bug-7522.php |  8 ++++++++
 3 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 tests/PHPStan/Rules/Functions/data/bug-7522.php

diff --git a/src/Reflection/SignatureMap/Php8SignatureMapProvider.php b/src/Reflection/SignatureMap/Php8SignatureMapProvider.php
index 7bfdf37f9b..8a0d689f66 100644
--- a/src/Reflection/SignatureMap/Php8SignatureMapProvider.php
+++ b/src/Reflection/SignatureMap/Php8SignatureMapProvider.php
@@ -3,6 +3,7 @@
 namespace PHPStan\Reflection\SignatureMap;
 
 use PhpParser\Node\AttributeGroup;
+use PhpParser\Node\Expr\ConstFetch;
 use PhpParser\Node\Expr\Variable;
 use PhpParser\Node\Scalar\String_;
 use PhpParser\Node\Stmt\ClassConst;
@@ -21,6 +22,7 @@
 use PHPStan\Type\MixedType;
 use PHPStan\Type\ParserNodeTypeToPHPStanType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
 use PHPStan\Type\TypehintHelper;
 use ReflectionFunctionAbstract;
 use function array_key_exists;
@@ -400,10 +402,23 @@ private function getSignature(
 				throw new ShouldNotHappenException();
 			}
 			$parameterType = ParserNodeTypeToPHPStanType::resolve($param->type, null);
+			$phpDocParameterType = $phpDocParameterTypes[$name->name] ?? null;
+
+			if ($param->default instanceof ConstFetch) {
+				$constName = (string) $param->default->name;
+				$loweredConstName = strtolower($constName);
+				if ($loweredConstName === 'null') {
+					$parameterType = TypeCombinator::addNull($parameterType);
+					if ($phpDocParameterType !== null) {
+						$phpDocParameterType = TypeCombinator::addNull($phpDocParameterType);
+					}
+				}
+			}
+
 			$parameters[] = new ParameterSignature(
 				$name->name,
 				$param->default !== null || $param->variadic,
-				TypehintHelper::decideType($parameterType, $phpDocParameterTypes[$name->name] ?? null),
+				TypehintHelper::decideType($parameterType, $phpDocParameterType),
 				$parameterType,
 				$param->byRef ? PassedByReference::createCreatesNewVariable() : PassedByReference::createNo(),
 				$param->variadic,
diff --git a/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php b/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
index 98927b4bd2..61cc6e6fc6 100644
--- a/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
+++ b/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
@@ -1793,4 +1793,10 @@ public function testBug7082(): void
 		]);
 	}
 
+	public function testBug7522(): void
+	{
+		$this->checkExplicitMixed = true;
+		$this->analyse([__DIR__ . '/data/bug-7522.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Functions/data/bug-7522.php b/tests/PHPStan/Rules/Functions/data/bug-7522.php
new file mode 100644
index 0000000000..cff0bc5897
--- /dev/null
+++ b/tests/PHPStan/Rules/Functions/data/bug-7522.php
@@ -0,0 +1,8 @@
+<?php declare(strict_types=1);
+
+namespace Bug7522;
+
+function doFoo() {
+	// Example #2 from https://www.php.net/manual/en/function.ob-start.php
+	\ob_start(null, 0, PHP_OUTPUT_HANDLER_STDFLAGS ^ PHP_OUTPUT_HANDLER_REMOVABLE);
+}