Fixes

src/Psalm/Internal/Analyzer/Statements/Expression/Call/ArrayFunctionArgumentsAnalyzer.php

@@ -267,9 +267,13 @@ class ArrayFunctionArgumentsAnalyzer
 
                             if ($was_list) {
                                 if ($arg_value_atomic_type instanceof TNonEmptyArray) {
-                                    $arg_value_atomic_type = Type::getNonEmptyListAtomic($arg_value_atomic_type->type_params[1]);
+                                    $arg_value_atomic_type = Type::getNonEmptyListAtomic(
+                                        $arg_value_atomic_type->type_params[1]
+                                    );
                                 } else {
-                                    $arg_value_atomic_type = Type::getListAtomic($arg_value_atomic_type->type_params[1]);
+                                    $arg_value_atomic_type = Type::getListAtomic(
+                                        $arg_value_atomic_type->type_params[1]
+                                    );
                                 }
                             }
 

src/Psalm/Internal/Analyzer/Statements/UnsetAnalyzer.php

@@ -87,9 +87,15 @@ class UnsetAnalyzer
                                     if ($key_value === 0) {
                                         $list_key = new Union([new TIntRange(1, null)]);
                                     } elseif ($key_value === 1) {
-                                        $list_key = new Union([new TLiteralInt(0), new TIntRange(2, null)]);
+                                        $list_key = new Union([
+                                            new TLiteralInt(0),
+                                            new TIntRange(2, null)
+                                        ]);
                                     } else {
-                                        $list_key = new Union([new TIntRange(0, $key_value-1), new TIntRange($key_value+1, null)]);
+                                        $list_key = new Union([
+                                            new TIntRange(0, $key_value-1),
+                                            new TIntRange($key_value+1, null)
+                                        ]);
                                     }
                                 }
 

src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayMergeReturnTypeProvider.php

@@ -107,6 +107,9 @@ class ArrayMergeReturnTypeProvider implements FunctionReturnTypeProviderInterfac
 
                         $added_inner_values = false;
                         foreach ($unpacked_type_part->properties as $key => $type) {
+                            if (!$type->possibly_undefined && !$unpacking_possibly_empty) {
+                                $any_nonempty = true;
+                            }
                             if (is_string($key)) {
                                 $all_int_offsets = false;
                             } elseif (!$is_replace) {
@@ -152,11 +155,7 @@ class ArrayMergeReturnTypeProvider implements FunctionReturnTypeProviderInterfac
                             $inner_key_types []= new TInt;
                         }
 
-                        if ($unpacked_type_part->fallback_params === null) {
+                        if ($unpacked_type_part->fallback_params !== null) {
-                            if (!$unpacking_possibly_empty) {
-                                $any_nonempty = true;
-                            }
-                        } else {
                             $all_keyed_arrays = false;
                             $inner_value_types = array_merge(
                                 $inner_value_types,

src/Psalm/Internal/Type/Comparator/AtomicTypeComparator.php

@@ -37,6 +37,7 @@ use Psalm\Type\Atomic\TValueOf;
 
 use function array_merge;
 use function array_values;
+use function assert;
 use function count;
 use function get_class;
 use function strtolower;
@@ -540,10 +541,6 @@ class AtomicTypeComparator
                 foreach ($input_type_part->type_params as $i => $input_param) {
                     $container_param_offset = $i - (2 - count($container_type_part->type_params));
 
-                    if ($container_param_offset === -1) {
-                        continue;
-                    }
-
                     $container_param = $container_type_part->type_params[$container_param_offset];
 
                     if ($i === 0
@@ -729,6 +726,9 @@ class AtomicTypeComparator
         return $input_type_part->getKey() === $container_type_part->getKey();
     }
 
+    /**
+     * @psalm-assert-if-true TKeyedArray $array
+     */
     public static function isLegacyTListLike(Atomic $array): bool
     {
         return $array instanceof TKeyedArray
@@ -739,6 +739,9 @@ class AtomicTypeComparator
             && $array->properties[0]->equals($array->fallback_params[1], true, true, false)
         ;
     }
+    /**
+     * @psalm-assert-if-true TKeyedArray $array
+     */
     public static function isLegacyTNonEmptyListLike(Atomic $array): bool
     {
         return $array instanceof TKeyedArray
@@ -763,6 +766,8 @@ class AtomicTypeComparator
             || (self::isLegacyTListLike($type2_part)
                 && self::isLegacyTNonEmptyListLike($type1_part))
         ) {
+            assert($type1_part->fallback_params !== null);
+            assert($type2_part->fallback_params !== null);
             return UnionTypeComparator::canExpressionTypesBeIdentical(
                 $codebase,
                 $type1_part->fallback_params[1],