Fix array_slice with non-empty-array

Author: ondrejmirtes

src/Type/Php/ArraySliceFunctionReturnTypeExtension.php

@@ -61,7 +61,7 @@ public function getTypeFromFunctionCall(
 
 		$constantArrays = TypeUtils::getConstantArrays($valueType);
 		if (count($constantArrays) === 0) {
-			return $valueType;
+			return TypeCombinator::union(...TypeUtils::getArrays($valueType));
 		}
 
 		if (isset($functionCall->args[3])) {

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -10225,6 +10225,11 @@ public function dataBug3985(): array
 		return $this->gatherAssertTypes(__DIR__ . '/data/bug-3985.php');
 	}
 
+	public function dataArraySliceNonEmpty(): array
+	{
+		return $this->gatherAssertTypes(__DIR__ . '/data/array-slice-non-empty.php');
+	}
+
 	/**
 	 * @dataProvider dataBug2574
 	 * @dataProvider dataBug2577
@@ -10312,6 +10317,7 @@ public function dataBug3985(): array
 	 * @dataProvider dataBug2816
 	 * @dataProvider dataBug2816Two
 	 * @dataProvider dataBug3985
+	 * @dataProvider dataArraySliceNonEmpty
 	 * @param string $assertType
 	 * @param string $file
 	 * @param mixed ...$args

tests/PHPStan/Analyser/data/array-slice-non-empty.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace ArraySliceNonEmpty;
+
+use function PHPStan\Analyser\assertType;
+
+class Foo
+{
+
+	/**
+	 * @param non-empty-array $a
+	 */
+	public function doFoo(array $a): void
+	{
+		assertType('array', array_slice($a, 1));
+	}
+
+}