From f27f0a3c1284acdce7c4cf10d676fcd226e4a572 Mon Sep 17 00:00:00 2001
From: Can Vural <can9119@gmail.com>
Date: Thu, 13 Jan 2022 13:59:26 +0100
Subject: [PATCH] Fix inferring template types in ClosureType

---
 src/Type/ClosureType.php                      |  2 +-
 .../PHPStan/Analyser/data/generic-unions.php  | 32 +++++++++++++++++++
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/src/Type/ClosureType.php b/src/Type/ClosureType.php
index 5c9ebacb01f..d6747060e4e 100644
--- a/src/Type/ClosureType.php
+++ b/src/Type/ClosureType.php
@@ -334,7 +334,7 @@ public function inferTemplateTypes(Type $receivedType): TemplateTypeMap
 			return $receivedType->inferTemplateTypesOn($this);
 		}
 
-		if ($receivedType->isCallable()->no()) {
+		if ($receivedType->isCallable()->no() || ! $receivedType instanceof self) {
 			return TemplateTypeMap::createEmpty();
 		}
 
diff --git a/tests/PHPStan/Analyser/data/generic-unions.php b/tests/PHPStan/Analyser/data/generic-unions.php
index 7ebc5bb89b8..0616294cb0c 100644
--- a/tests/PHPStan/Analyser/data/generic-unions.php
+++ b/tests/PHPStan/Analyser/data/generic-unions.php
@@ -61,3 +61,35 @@ public function foo(
 	}
 
 }
+
+/**
+ *
+ * @template TGetDefault
+ * @template TKey
+ *
+ * @param  TKey  $key
+ * @param  TGetDefault|(\Closure(): TGetDefault)  $default
+ * @return TKey|TGetDefault
+ */
+function getWithDefault($key, $default = null)
+{
+	if(rand(0,10) > 5) {
+		return $key;
+	}
+
+	if (is_callable($default)) {
+		return $default();
+	}
+
+	return $default;
+}
+
+assertType('int|null', getWithDefault(3));
+assertType('int|string', getWithDefault(3, 'foo'));
+assertType('int|string', getWithDefault(3, function () {
+	return 'foo';
+}));
+assertType('GenericUnions\Foo|int', getWithDefault(3, function () {
+	return new Foo;
+}));
+assertType('GenericUnions\Foo|int', getWithDefault(3, new Foo));