[TypeDeclaration] Skip nullable generic typed on ReturnTypeDeclaratio…

…nRector (#985)

Co-authored-by: GitHub Action <[email protected]>

rules-tests/TypeDeclaration/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/nullable_generic_return_not_typed.php.inc

@@ -0,0 +1,109 @@
+<?php
+
+namespace Rector\Tests\TypeDeclaration\Rector\FunctionLike\ReturnTypeDeclarationRector\Fixture;
+
+/** @return array<array<mixed>>|null */
+function foo1(int $a, float $b)
+{
+    $bar = null;
+
+    if ($a > 0) {
+        for ($i = 0; $i < $a; $i++) {
+            $bar[] = [
+                'a' => $a,
+                'b' => $b,
+            ];
+        }
+    }
+
+    return $bar;
+}
+
+/** @return array{a: int, b: float}|null */
+function foo2(int $a, float $b)
+{
+    $bar = null;
+
+    if ($a > 0) {
+        $bar = [
+            'a' => $a,
+            'b' => $b,
+        ];
+    }
+
+    return $bar;
+}
+
+/** @return array<array{a: int, b: float}>|null */
+function foo3(int $a, float $b)
+{
+    $bar = null;
+
+    if ($a > 0) {
+        for ($i = 0; $i < $a; $i++) {
+            $bar[] = [
+                'a' => $a,
+                'b' => $b,
+            ];
+        }
+    }
+
+    return $bar;
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Tests\TypeDeclaration\Rector\FunctionLike\ReturnTypeDeclarationRector\Fixture;
+
+/** @return array<array<mixed>>|null */
+function foo1(int $a, float $b): ?array
+{
+    $bar = null;
+
+    if ($a > 0) {
+        for ($i = 0; $i < $a; $i++) {
+            $bar[] = [
+                'a' => $a,
+                'b' => $b,
+            ];
+        }
+    }
+
+    return $bar;
+}
+
+/** @return array{a: int, b: float}|null */
+function foo2(int $a, float $b): ?array
+{
+    $bar = null;
+
+    if ($a > 0) {
+        $bar = [
+            'a' => $a,
+            'b' => $b,
+        ];
+    }
+
+    return $bar;
+}
+
+/** @return array<array{a: int, b: float}>|null */
+function foo3(int $a, float $b): ?array
+{
+    $bar = null;
+
+    if ($a > 0) {
+        for ($i = 0; $i < $a; $i++) {
+            $bar[] = [
+                'a' => $a,
+                'b' => $b,
+            ];
+        }
+    }
+
+    return $bar;
+}
+
+?>

rules-tests/TypeDeclaration/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/skip_nullable_generic_return_typed.php.inc

@@ -0,0 +1,52 @@
+<?php
+
+namespace Rector\Tests\TypeDeclaration\Rector\FunctionLike\ReturnTypeDeclarationRector\Fixture;
+
+/** @return array<array<mixed>>|null */
+function foo1(int $a, float $b): ?array
+{
+    $bar = null;
+
+    if ($a > 0) {
+        for ($i = 0; $i < $a; $i++) {
+            $bar[] = [
+                'a' => $a,
+                'b' => $b,
+            ];
+        }
+    }
+
+    return $bar;
+}
+
+/** @return array{a: int, b: float}|null */
+function foo2(int $a, float $b): ?array
+{
+    $bar = null;
+
+    if ($a > 0) {
+        $bar = [
+            'a' => $a,
+            'b' => $b,
+        ];
+    }
+
+    return $bar;
+}
+
+/** @return array<array{a: int, b: float}>|null */
+function foo3(int $a, float $b): ?array
+{
+    $bar = null;
+
+    if ($a > 0) {
+        for ($i = 0; $i < $a; $i++) {
+            $bar[] = [
+                'a' => $a,
+                'b' => $b,
+            ];
+        }
+    }
+
+    return $bar;
+}

rules/TypeDeclaration/TypeAnalyzer/GenericClassStringTypeNormalizer.php

@@ -12,6 +12,7 @@
 use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\Generic\GenericClassStringType;
 use PHPStan\Type\MixedType;
+use PHPStan\Type\NullType;
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\StringType;
 use PHPStan\Type\Type;
@@ -48,7 +49,7 @@ public function normalize(Type $type): ArrayType | UnionType | Type
             return $this->resolveStringType($value);
         });
 
-        if ($type instanceof UnionType) {
+        if ($type instanceof UnionType && ! $this->isNullableType($type)) {
             return $this->resolveClassStringInUnionType($type);
         }
 
@@ -72,6 +73,22 @@ public function isAllGenericClassStringType(UnionType $unionType): bool
         return true;
     }
 
+    private function isNullableType(UnionType $unionType): bool
+    {
+        $types = $unionType->getTypes();
+        if (count($types) > 2) {
+            return false;
+        }
+
+        foreach ($types as $type) {
+            if ($type instanceof NullType) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     private function resolveArrayTypeWithUnionKeyType(ArrayType $arrayType): ArrayType
     {
         $itemType = $arrayType->getItemType();