Fix resolving variants for union type methods

src/Reflection/Type/UnionTypeMethodReflection.php

@@ -4,13 +4,13 @@
 
 use PHPStan\Reflection\ClassMemberReflection;
 use PHPStan\Reflection\ClassReflection;
-use PHPStan\Reflection\FunctionVariant;
 use PHPStan\Reflection\MethodReflection;
-use PHPStan\Reflection\ParametersAcceptor;
+use PHPStan\Reflection\ParametersAcceptorSelector;
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
 use function array_map;
+use function array_merge;
 use function count;
 use function implode;
 
@@ -74,16 +74,9 @@ public function getPrototype(): ClassMemberReflection
 
 	public function getVariants(): array
 	{
-		$variants = $this->methods[0]->getVariants();
-		$returnType = TypeCombinator::union(...array_map(static fn (MethodReflection $method): Type => TypeCombinator::union(...array_map(static fn (ParametersAcceptor $acceptor): Type => $acceptor->getReturnType(), $method->getVariants())), $this->methods));
-
-		return array_map(static fn (ParametersAcceptor $acceptor): ParametersAcceptor => new FunctionVariant(
-			$acceptor->getTemplateTypeMap(),
-			$acceptor->getResolvedTemplateTypeMap(),
-			$acceptor->getParameters(),
-			$acceptor->isVariadic(),
-			$returnType,
-		), $variants);
+		$variants = array_merge(...array_map(static fn (MethodReflection $method) => $method->getVariants(), $this->methods));
+
+		return [ParametersAcceptorSelector::combineAcceptors($variants)];
 	}
 
 	public function isDeprecated(): TrinaryLogic

tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php

@@ -2498,4 +2498,13 @@ public function testBug1517(): void
 		$this->analyse([__DIR__ . '/data/bug-1517.php'], []);
 	}
 
+	public function testBug7593(): void
+	{
+		$this->checkThisOnly = false;
+		$this->checkNullables = true;
+		$this->checkUnionTypes = true;
+		$this->checkExplicitMixed = true;
+		$this->analyse([__DIR__ . '/data/bug-7593.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Methods/data/bug-7593.php

@@ -0,0 +1,33 @@
+<?php declare(strict_types = 1); // lint >= 8.0
+
+namespace Bug7593;
+
+/** @template T */
+class Collection {
+	/** @param T $item */
+	public function add(mixed $item): void {}
+}
+
+class Foo {}
+class Bar {}
+
+class CollectionManager
+{
+	/**
+	* @param Collection<Foo> $fooCollection
+	* @param Collection<Bar> $barCollection
+	*/
+	public function __construct(
+		private Collection $fooCollection,
+		private Collection $barCollection,
+	) {}
+
+	public function updateCollection(Foo|Bar $foobar): void
+	{
+		(match(get_class($foobar)) {
+			Foo::class => $this->fooCollection,
+			Bar::class => $this->barCollection,
+			default => throw new LogicException(),
+		})->add($foobar);
+	}
+}