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));
+}
+
+}