From 54ac13b190b96097d6663c9b6cc50a5b859d8e11 Mon Sep 17 00:00:00 2001
From: Matt Brown <github@muglug.com>
Date: Sun, 28 Mar 2021 09:52:23 -0400
Subject: [PATCH] Allow nested template unwrapping inside `reset`, `end`

Fixes #5208
---
 ...rayPointerAdjustmentReturnTypeProvider.php | 54 ++++++++++++-------
 ...emplateTest.php => NestedTemplateTest.php} | 14 ++++-
 2 files changed, 47 insertions(+), 21 deletions(-)
 rename tests/Template/{NestedClassTemplateTest.php => NestedTemplateTest.php} (91%)

diff --git a/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayPointerAdjustmentReturnTypeProvider.php b/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayPointerAdjustmentReturnTypeProvider.php
index 8935be6e0..553a78172 100644
--- a/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayPointerAdjustmentReturnTypeProvider.php
+++ b/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayPointerAdjustmentReturnTypeProvider.php
@@ -26,29 +26,43 @@ class ArrayPointerAdjustmentReturnTypeProvider implements \Psalm\Plugin\EventHan
 
         $first_arg = isset($call_args[0]->value) ? $call_args[0]->value : null;
 
-        $first_arg_array = $first_arg
-            && ($first_arg_type = $statements_source->node_data->getType($first_arg))
-            && $first_arg_type->hasType('array')
-            && ($array_atomic_type = $first_arg_type->getAtomicTypes()['array'])
-            && ($array_atomic_type instanceof Type\Atomic\TArray
-                || $array_atomic_type instanceof Type\Atomic\TKeyedArray
-                || $array_atomic_type instanceof Type\Atomic\TList)
-        ? $array_atomic_type
-        : null;
-
-        if (!$first_arg_array) {
+        if (!$first_arg) {
             return Type::getMixed();
         }
 
-        if ($first_arg_array instanceof Type\Atomic\TArray) {
-            $value_type = clone $first_arg_array->type_params[1];
-            $definitely_has_items = $first_arg_array instanceof Type\Atomic\TNonEmptyArray;
-        } elseif ($first_arg_array instanceof Type\Atomic\TList) {
-            $value_type = clone $first_arg_array->type_param;
-            $definitely_has_items = $first_arg_array instanceof Type\Atomic\TNonEmptyList;
-        } else {
-            $value_type = $first_arg_array->getGenericValueType();
-            $definitely_has_items = $first_arg_array->getGenericArrayType() instanceof Type\Atomic\TNonEmptyArray;
+        $first_arg_type = $statements_source->node_data->getType($first_arg);
+
+        if (!$first_arg_type) {
+            return Type::getMixed();
+        }
+
+        $atomic_types = $first_arg_type->getAtomicTypes();
+
+        $value_type = null;
+        $definitely_has_items = false;
+
+        while ($atomic_type = array_shift($atomic_types)) {
+            if ($atomic_type instanceof Type\Atomic\TTemplateParam) {
+                $atomic_types = \array_merge($atomic_types, $atomic_type->as->getAtomicTypes());
+                continue;
+            }
+
+            if ($atomic_type instanceof Type\Atomic\TArray) {
+                $value_type = clone $atomic_type->type_params[1];
+                $definitely_has_items = $atomic_type instanceof Type\Atomic\TNonEmptyArray;
+            } elseif ($atomic_type instanceof Type\Atomic\TList) {
+                $value_type = clone $atomic_type->type_param;
+                $definitely_has_items = $atomic_type instanceof Type\Atomic\TNonEmptyList;
+            } elseif ($atomic_type instanceof Type\Atomic\TKeyedArray) {
+                $value_type = $atomic_type->getGenericValueType();
+                $definitely_has_items = $atomic_type->getGenericArrayType() instanceof Type\Atomic\TNonEmptyArray;
+            } else {
+                return Type::getMixed();
+            }
+        }
+
+        if (!$value_type) {
+            throw new \UnexpectedValueException('This should never happen');
         }
 
         if ($value_type->isEmpty()) {
diff --git a/tests/Template/NestedClassTemplateTest.php b/tests/Template/NestedTemplateTest.php
similarity index 91%
rename from tests/Template/NestedClassTemplateTest.php
rename to tests/Template/NestedTemplateTest.php
index ea48599d1..00a3e2571 100644
--- a/tests/Template/NestedClassTemplateTest.php
+++ b/tests/Template/NestedTemplateTest.php
@@ -5,7 +5,7 @@ use const DIRECTORY_SEPARATOR;
 use Psalm\Tests\TestCase;
 use Psalm\Tests\Traits;
 
-class NestedClassTemplateTest extends TestCase
+class NestedTemplateTest extends TestCase
 {
     use Traits\InvalidCodeAnalysisTestTrait;
     use Traits\ValidCodeAnalysisTestTrait;
@@ -107,6 +107,18 @@ class NestedClassTemplateTest extends TestCase
 
                     $result = load(StringWrapper::class);'
             ],
+            'unwrapNestedTemplateWithReset' => [
+                '<?php
+                    /**
+                     * @template TValue
+                     * @template TArray of non-empty-array<TValue>
+                     * @param TArray $arr
+                     * @return TValue
+                     */
+                    function toList(array $arr): array {
+                        return reset($arr);
+                    }'
+            ],
         ];
     }