From 992f26a8e7e634118d8f63aedcb97f9c164ec681 Mon Sep 17 00:00:00 2001
From: Daniil Gentili <daniil@daniil.it>
Date: Fri, 16 Dec 2022 18:10:46 +0100
Subject: [PATCH 1/3] Fix array_merge edge case

---
 .../ArrayMergeReturnTypeProvider.php           | 14 +++++++++++---
 tests/ArrayFunctionCallTest.php                | 18 ++++++++++++++++++
 2 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayMergeReturnTypeProvider.php b/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayMergeReturnTypeProvider.php
index 05efc3c4ef2..12a9854626c 100644
--- a/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayMergeReturnTypeProvider.php
+++ b/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayMergeReturnTypeProvider.php
@@ -130,10 +130,18 @@ public static function getFunctionReturnType(FunctionReturnTypeProviderEvent $ev
                                 $class_strings[$key] = true;
                             }
 
-                            if (!isset($generic_properties[$key]) || !$type->possibly_undefined) {
+                            if (!isset($generic_properties[$key]) || (
+                                !$type->possibly_undefined
+                                    && !$unpacking_possibly_empty
+                                    && $is_replace
+                            )) {
+                                if ($unpacking_possibly_empty) {
+                                    $type = $type->setPossiblyUndefined(true);
+                                }
                                 $generic_properties[$key] = $type;
                             } else {
-                                $was_possibly_undefined = $generic_properties[$key]->possibly_undefined;
+                                $was_possibly_undefined = $generic_properties[$key]->possibly_undefined
+                                    || $unpacking_possibly_empty;
 
                                 $generic_properties[$key] = Type::combineUnionTypes(
                                     $generic_properties[$key],
@@ -147,7 +155,7 @@ public static function getFunctionReturnType(FunctionReturnTypeProviderEvent $ev
                             }
                         }
 
-                        if (!$unpacked_type_part->is_list && !$unpacking_possibly_empty) {
+                        if (!$unpacked_type_part->is_list) {
                             $all_nonempty_lists = false;
                         }
 
diff --git a/tests/ArrayFunctionCallTest.php b/tests/ArrayFunctionCallTest.php
index 369b6aae59c..3189266a0cb 100644
--- a/tests/ArrayFunctionCallTest.php
+++ b/tests/ArrayFunctionCallTest.php
@@ -211,6 +211,24 @@ function getInts(): array { return [123]; }
                 'ignored_issues' => [],
                 'php_version' => '8.0',
             ],
+            'arrayMergeListOfShapes' => [
+                'code' => '<?php
+
+                    /** @var list<array{a: int}> */
+                    $a = [];
+
+                    $b = array_merge(...$a);
+
+                    /** @var non-empty-list<array{a: int}> */
+                    $c = [];
+
+                    $d = array_merge(...$c);
+                ',
+                'assertions' => [
+                    '$b' => 'array{a?: int}',
+                    '$d' => 'array{a: int}',
+                ]
+            ],
             'arrayMergeIntArrays' => [
                 'code' => '<?php
                     $d = array_merge(["a", "b", "c", "d"], [1, 2, 3]);',

From f5b6889c326d6373d3e40e5a28f388d4bb2d4695 Mon Sep 17 00:00:00 2001
From: Daniil Gentili <daniil@daniil.it>
Date: Fri, 16 Dec 2022 18:39:35 +0100
Subject: [PATCH 2/3] Fix

---
 .../ReturnTypeProvider/ArrayMergeReturnTypeProvider.php       | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayMergeReturnTypeProvider.php b/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayMergeReturnTypeProvider.php
index 12a9854626c..27b26595823 100644
--- a/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayMergeReturnTypeProvider.php
+++ b/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayMergeReturnTypeProvider.php
@@ -47,7 +47,7 @@ public static function getFunctionReturnType(FunctionReturnTypeProviderEvent $ev
             return Type::getMixed();
         }
 
-        $is_replace = substr($event->getFunctionId(), 6, 7) === 'replace';
+        $is_replace = $event->getFunctionId() === 'array_replace';
 
         $inner_value_types = [];
         $inner_key_types = [];
@@ -113,7 +113,7 @@ public static function getFunctionReturnType(FunctionReturnTypeProviderEvent $ev
                             }
                             if (is_string($key)) {
                                 $all_int_offsets = false;
-                            } elseif (!$is_replace) {
+                            } else if (!$is_replace) {
                                 if ($unpacking_indefinite_number_of_args || $type->possibly_undefined) {
                                     $added_inner_values = true;
                                     $inner_value_types = array_merge(

From 2c00c64304b8230995552b6af6d4c309b5fb0525 Mon Sep 17 00:00:00 2001
From: Daniil Gentili <daniil@daniil.it>
Date: Fri, 16 Dec 2022 19:18:33 +0100
Subject: [PATCH 3/3] Bypass bug

---
 psalm-baseline.xml                            | 69 ++-----------------
 .../ArrayMergeReturnTypeProvider.php          |  3 +-
 2 files changed, 5 insertions(+), 67 deletions(-)

diff --git a/psalm-baseline.xml b/psalm-baseline.xml
index 81a14de0338..b8dacf52dee 100644
--- a/psalm-baseline.xml
+++ b/psalm-baseline.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<files psalm-version="dev-master@2b0e979ee9434afdeb9dd59a3219bf4029c62dc8">
+<files psalm-version="dev-master@6eb37b9dc2321e4eaade9d3d2dca1aff6f2c0a8f">
   <file src="examples/TemplateChecker.php">
     <PossiblyUndefinedIntArrayOffset occurrences="2">
       <code>$comment_block-&gt;tags['variablesfrom'][0]</code>
@@ -390,6 +390,9 @@
     <InvalidArgument occurrences="1">
       <code>$class_strings ?: null</code>
     </InvalidArgument>
+    <RedundantCondition occurrences="2">
+      <code>$is_replace</code>
+    </RedundantCondition>
   </file>
   <file src="src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayReduceReturnTypeProvider.php">
     <PossiblyUndefinedIntArrayOffset occurrences="1">
@@ -593,10 +596,6 @@
     <ImpurePropertyAssignment occurrences="1">
       <code>$key_type-&gt;possibly_undefined</code>
     </ImpurePropertyAssignment>
-    <InvalidPropertyAssignmentValue occurrences="2">
-      <code>$fallback_params</code>
-      <code>$fallback_params</code>
-    </InvalidPropertyAssignmentValue>
     <PossiblyUndefinedIntArrayOffset occurrences="3">
       <code>$this-&gt;properties[0]</code>
       <code>$this-&gt;properties[0]</code>
@@ -705,64 +704,4 @@
       <code>$subNodes['expr']</code>
     </PossiblyUndefinedStringArrayOffset>
   </file>
-  <file src="vendor/nikic/php-parser/lib/PhpParser/Node/Expr/ShellExec.php">
-    <InvalidPropertyAssignmentValue occurrences="1">
-      <code>$parts</code>
-    </InvalidPropertyAssignmentValue>
-  </file>
-  <file src="vendor/nikic/php-parser/lib/PhpParser/Node/MatchArm.php">
-    <InvalidPropertyAssignmentValue occurrences="1">
-      <code>$conds</code>
-    </InvalidPropertyAssignmentValue>
-  </file>
-  <file src="vendor/nikic/php-parser/lib/PhpParser/Node/Name.php">
-    <InvalidPropertyAssignmentValue occurrences="1">
-      <code>self::prepareName($name)</code>
-    </InvalidPropertyAssignmentValue>
-  </file>
-  <file src="vendor/nikic/php-parser/lib/PhpParser/Node/Stmt/Case_.php">
-    <InvalidPropertyAssignmentValue occurrences="1">
-      <code>$stmts</code>
-    </InvalidPropertyAssignmentValue>
-  </file>
-  <file src="vendor/nikic/php-parser/lib/PhpParser/Node/Stmt/Catch_.php">
-    <InvalidPropertyAssignmentValue occurrences="1">
-      <code>$stmts</code>
-    </InvalidPropertyAssignmentValue>
-  </file>
-  <file src="vendor/nikic/php-parser/lib/PhpParser/Node/Stmt/Do_.php">
-    <InvalidPropertyAssignmentValue occurrences="1">
-      <code>$stmts</code>
-    </InvalidPropertyAssignmentValue>
-  </file>
-  <file src="vendor/nikic/php-parser/lib/PhpParser/Node/Stmt/ElseIf_.php">
-    <InvalidPropertyAssignmentValue occurrences="1">
-      <code>$stmts</code>
-    </InvalidPropertyAssignmentValue>
-  </file>
-  <file src="vendor/nikic/php-parser/lib/PhpParser/Node/Stmt/Else_.php">
-    <InvalidPropertyAssignmentValue occurrences="1">
-      <code>$stmts</code>
-    </InvalidPropertyAssignmentValue>
-  </file>
-  <file src="vendor/nikic/php-parser/lib/PhpParser/Node/Stmt/Finally_.php">
-    <InvalidPropertyAssignmentValue occurrences="1">
-      <code>$stmts</code>
-    </InvalidPropertyAssignmentValue>
-  </file>
-  <file src="vendor/nikic/php-parser/lib/PhpParser/Node/Stmt/Namespace_.php">
-    <InvalidPropertyAssignmentValue occurrences="1">
-      <code>$stmts</code>
-    </InvalidPropertyAssignmentValue>
-  </file>
-  <file src="vendor/nikic/php-parser/lib/PhpParser/Node/Stmt/TryCatch.php">
-    <InvalidPropertyAssignmentValue occurrences="1">
-      <code>$stmts</code>
-    </InvalidPropertyAssignmentValue>
-  </file>
-  <file src="vendor/nikic/php-parser/lib/PhpParser/Node/Stmt/While_.php">
-    <InvalidPropertyAssignmentValue occurrences="1">
-      <code>$stmts</code>
-    </InvalidPropertyAssignmentValue>
-  </file>
 </files>
diff --git a/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayMergeReturnTypeProvider.php b/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayMergeReturnTypeProvider.php
index 27b26595823..e66ed4a5c4f 100644
--- a/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayMergeReturnTypeProvider.php
+++ b/src/Psalm/Internal/Provider/ReturnTypeProvider/ArrayMergeReturnTypeProvider.php
@@ -22,7 +22,6 @@
 use function count;
 use function is_string;
 use function max;
-use function substr;
 
 /**
  * @internal
@@ -113,7 +112,7 @@ public static function getFunctionReturnType(FunctionReturnTypeProviderEvent $ev
                             }
                             if (is_string($key)) {
                                 $all_int_offsets = false;
-                            } else if (!$is_replace) {
+                            } elseif (!$is_replace) {
                                 if ($unpacking_indefinite_number_of_args || $type->possibly_undefined) {
                                     $added_inner_values = true;
                                     $inner_value_types = array_merge(