Fix variadic parameters for generics

Author: ondrejmirtes

src/Reflection/GenericParametersAcceptorResolver.php

@@ -5,7 +5,11 @@
 use PHPStan\Type\ErrorType;
 use PHPStan\Type\Generic\TemplateTypeMap;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
+use function array_key_exists;
 use function array_merge;
+use function count;
+use function is_int;
 
 class GenericParametersAcceptorResolver
 {
@@ -18,15 +22,38 @@ public static function resolve(array $argTypes, ParametersAcceptor $parametersAc
 	{
 		$typeMap = TemplateTypeMap::createEmpty();
 
-		foreach ($parametersAcceptor->getParameters() as $i => $param) {
-			if (isset($argTypes[$i])) {
-				$argType = $argTypes[$i];
-			} elseif (isset($argTypes[$param->getName()])) {
-				$argType = $argTypes[$param->getName()];
+		$parameters = $parametersAcceptor->getParameters();
+		$namedArgTypes = [];
+		foreach ($argTypes as $i => $argType) {
+			if (is_int($i)) {
+				if (isset($parameters[$i])) {
+					$namedArgTypes[$parameters[$i]->getName()] = $argType;
+					continue;
+				}
+				if (count($parameters) > 0) {
+					$lastParameter = $parameters[count($parameters) - 1];
+					if ($lastParameter->isVariadic()) {
+						$parameterName = $lastParameter->getName();
+						if (array_key_exists($parameterName, $namedArgTypes)) {
+							$namedArgTypes[$parameterName] = TypeCombinator::union($namedArgTypes[$parameterName], $argType);
+							continue;
+						}
+						$namedArgTypes[$parameterName] = $argType;
+					}
+				}
+				continue;
+			}
+
+			$namedArgTypes[$i] = $argType;
+		}
+
+		foreach ($parametersAcceptor->getParameters() as $param) {
+			if (isset($namedArgTypes[$param->getName()])) {
+				$argType = $namedArgTypes[$param->getName()];
 			} elseif ($param->getDefaultValue() !== null) {
 				$argType = $param->getDefaultValue();
 			} else {
-				break;
+				continue;
 			}
 
 			$paramType = $param->getType();

tests/PHPStan/Analyser/AnalyserIntegrationTest.php

@@ -647,6 +647,12 @@ public function testBug6979(): void
 		$this->assertNoErrors($errors);
 	}
 
+	public function testBug7068(): void
+	{
+		$errors = $this->runAnalyse(__DIR__ . '/data/bug-7068.php');
+		$this->assertNoErrors($errors);
+	}
+
 	/**
 	 * @param string[]|null $allAnalysedFiles
 	 * @return Error[]

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -867,6 +867,7 @@ public function dataFileAsserts(): iterable
 
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6927.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/constant-array-optional-set.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-7068.php');
 	}
 
 	/**

tests/PHPStan/Analyser/data/bug-7068.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace Bug7068;
+
+use function PHPStan\Testing\assertType;
+
+class Foo
+{
+
+	/**
+	 * @template T
+	 * @param array<T> ...$arrays
+	 * @return array<T>
+	 */
+	function merge(array ...$arrays): array {
+		return array_merge(...$arrays);
+	}
+
+	public function doFoo(): void
+	{
+		assertType('array<int>', $this->merge([1, 2], [3, 4], [5]));
+		assertType('array<int|string>', $this->merge([1, 2], ['foo', 'bar']));
+	}
+
+}