From 7a66cb6eda85703811c7dce472355e036d70c144 Mon Sep 17 00:00:00 2001
From: Ondrej Mirtes <ondrej@mirtes.cz>
Date: Sat, 5 Mar 2022 12:56:34 +0100
Subject: [PATCH] Do not add null to a template type for a default parameter
 value null

---
 src/Reflection/Php/PhpParameterReflection.php |  7 ++-
 .../Analyser/NodeScopeResolverTest.php        |  1 +
 tests/PHPStan/Analyser/data/bug-6584.php      | 44 +++++++++++++++++++
 3 files changed, 51 insertions(+), 1 deletion(-)
 create mode 100644 tests/PHPStan/Analyser/data/bug-6584.php

diff --git a/src/Reflection/Php/PhpParameterReflection.php b/src/Reflection/Php/PhpParameterReflection.php
index 63be44cf3c..414a7722f0 100644
--- a/src/Reflection/Php/PhpParameterReflection.php
+++ b/src/Reflection/Php/PhpParameterReflection.php
@@ -6,6 +6,7 @@
 use PHPStan\Reflection\PassedByReference;
 use PHPStan\Type\ConstantTypeHelper;
 use PHPStan\Type\MixedType;
+use PHPStan\Type\NullType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
 use PHPStan\Type\TypehintHelper;
@@ -43,7 +44,11 @@ public function getType(): Type
 			$phpDocType = $this->phpDocType;
 			if ($phpDocType !== null) {
 				try {
-					if ($this->reflection->isDefaultValueAvailable() && $this->reflection->getDefaultValue() === null) {
+					if (
+						$this->reflection->isDefaultValueAvailable()
+						&& $this->reflection->getDefaultValue() === null
+						&& (new NullType())->isSuperTypeOf($phpDocType)->no()
+					) {
 						$phpDocType = TypeCombinator::addNull($phpDocType);
 					}
 				} catch (Throwable) {
diff --git a/tests/PHPStan/Analyser/NodeScopeResolverTest.php b/tests/PHPStan/Analyser/NodeScopeResolverTest.php
index 88a0da3a53..2c00be34fb 100644
--- a/tests/PHPStan/Analyser/NodeScopeResolverTest.php
+++ b/tests/PHPStan/Analyser/NodeScopeResolverTest.php
@@ -767,6 +767,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-5668.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/generics-empty-array.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Methods/data/bug-5757.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6584.php');
 	}
 
 	/**
diff --git a/tests/PHPStan/Analyser/data/bug-6584.php b/tests/PHPStan/Analyser/data/bug-6584.php
new file mode 100644
index 0000000000..c989a35199
--- /dev/null
+++ b/tests/PHPStan/Analyser/data/bug-6584.php
@@ -0,0 +1,44 @@
+<?php
+
+namespace Bug6584;
+
+use function PHPStan\Testing\assertType;
+
+class Foo
+{
+
+	public function doFoo(int $int, ?int $intOrNull)
+	{
+		assertType('int', $this->same($int));
+		assertType('int', $this->sameWithDefault($int));
+
+		assertType('int|null', $this->same($intOrNull));
+		assertType('int|null', $this->sameWithDefault($intOrNull));
+
+		assertType('null', $this->same(null));
+		assertType('null', $this->sameWithDefault(null));
+		assertType('null', $this->sameWithDefault());
+	}
+
+
+	/**
+	 * @template T
+	 * @param T $t
+	 * @return T
+	 */
+	function same($t) {
+		assertType('T (method Bug6584\Foo::same(), argument)', $t);
+		return $t;
+	}
+
+	/**
+	 * @template T
+	 * @param T $t
+	 * @return T
+	 */
+	function sameWithDefault($t = null) {
+		assertType('T (method Bug6584\Foo::sameWithDefault(), argument)', $t);
+		return $t;
+	}
+
+}