Fix TemplateUnionType as part of intersection

src/Type/TypeCombinator.php

@@ -13,6 +13,9 @@
 use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\Generic\GenericObjectType;
 use PHPStan\Type\Generic\TemplateType;
+use PHPStan\Type\Generic\TemplateTypeFactory;
+use PHPStan\Type\Generic\TemplateTypeHelper;
+use PHPStan\Type\Generic\TemplateUnionType;
 
 class TypeCombinator
 {
@@ -603,23 +606,37 @@ public static function intersect(Type ...$types): Type
 		});
 		// transform A & (B | C) to (A & B) | (A & C)
 		foreach ($types as $i => $type) {
-			if ($type instanceof UnionType) {
-				$topLevelUnionSubTypes = [];
-				foreach ($type->getTypes() as $innerUnionSubType) {
-					$topLevelUnionSubTypes[] = self::intersect(
-						$innerUnionSubType,
-						...array_slice($types, 0, $i),
-						...array_slice($types, $i + 1)
-					);
-				}
+			if (!$type instanceof UnionType) {
+				continue;
+			}
 
-				$union = self::union(...$topLevelUnionSubTypes);
-				if ($type instanceof BenevolentUnionType) {
-					return TypeUtils::toBenevolentUnion($union);
-				}
+			$topLevelUnionSubTypes = [];
+			foreach ($type->getTypes() as $innerUnionSubType) {
+				$topLevelUnionSubTypes[] = self::intersect(
+					$innerUnionSubType,
+					...array_slice($types, 0, $i),
+					...array_slice($types, $i + 1)
+				);
+			}
+
+			$union = self::union(...$topLevelUnionSubTypes);
+			if ($type instanceof BenevolentUnionType) {
+				$union = TypeUtils::toBenevolentUnion($union);
+			}
 
-				return $union;
+			if ($type instanceof TemplateUnionType) {
+				$union = TemplateTypeFactory::create(
+					$type->getScope(),
+					$type->getName(),
+					$union,
+					$type->getVariance()
+				);
+				if ($type->isArgument()) {
+					return TemplateTypeHelper::toArgument($union);
+				}
 			}
+
+			return $union;
 		}
 
 		// transform A & (B & C) to A & B & C

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -405,6 +405,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/getopt.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/generics-default.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-4985.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-5000.php');
 	}
 
 	/**

tests/PHPStan/Analyser/data/bug-5000.php

@@ -0,0 +1,53 @@
+<?php
+
+namespace Bug5000;
+
+use function PHPStan\Testing\assertType;
+
+class A {
+
+}
+
+class B {
+
+}
+
+/**
+ * @template T of A|B
+ */
+interface F
+{
+
+	/**
+	 * @return T[]
+	 */
+	function getValues(): array;
+
+	/**
+	 * @phpstan-param T $v
+	 * @return T
+	 */
+	function getDetail(object $v);
+}
+
+class Foo
+{
+
+	/**
+	 * @template T of A|B
+	 * @phpstan-param F<T> $f
+	 */
+	function foo(F $f): void {
+		$values = $f->getValues();
+		assertType('array<T of Bug5000\A|Bug5000\B (method Bug5000\Foo::foo(), argument)>', $values);
+
+		$f->getDetail($values[0]);
+		assertType('array<T of Bug5000\A|Bug5000\B (method Bug5000\Foo::foo(), argument)>', $values);
+		foreach($values as $val) {
+			assertType('T of Bug5000\A|Bug5000\B (method Bug5000\Foo::foo(), argument)', $val);
+			$f->getDetail($val);
+		}
+	}
+
+
+}