From 6f598464a974d2d7d8c00649edb73a1413d9c28e Mon Sep 17 00:00:00 2001
From: Matt Brown <github@muglug.com>
Date: Thu, 3 Dec 2020 13:09:08 -0500
Subject: [PATCH] Mixed array access should mark vars as used just in case

---
 .../Expression/Fetch/ArrayFetchAnalyzer.php   | 30 ++++++++++++++++++-
 tests/UnusedVariableTest.php                  | 15 ++++++++++
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/Fetch/ArrayFetchAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/Fetch/ArrayFetchAnalyzer.php
index 52972ea20..350f01df4 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/Fetch/ArrayFetchAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/Fetch/ArrayFetchAnalyzer.php
@@ -7,6 +7,7 @@ use Psalm\Internal\Analyzer\Statements\Expression\ExpressionIdentifier;
 use Psalm\Internal\Analyzer\StatementsAnalyzer;
 use Psalm\Internal\Type\Comparator\UnionTypeComparator;
 use Psalm\Internal\Codebase\TaintFlowGraph;
+use Psalm\Internal\DataFlow\DataFlowNode;
 use Psalm\Internal\Type\TemplateInferredTypeReplacer;
 use Psalm\CodeLocation;
 use Psalm\Context;
@@ -343,7 +344,7 @@ class ArrayFetchAnalyzer
 
             $var_location = new CodeLocation($statements_analyzer->getSource(), $var);
 
-            $new_parent_node = \Psalm\Internal\DataFlow\DataFlowNode::getForAssignment(
+            $new_parent_node = DataFlowNode::getForAssignment(
                 $keyed_array_var_id ?: 'array-fetch',
                 $var_location
             );
@@ -940,6 +941,33 @@ class ArrayFetchAnalyzer
             }
         }
 
+        if (($data_flow_graph = $statements_analyzer->data_flow_graph)
+            && $data_flow_graph instanceof \Psalm\Internal\Codebase\VariableUseGraph
+            && ($stmt_var_type = $statements_analyzer->node_data->getType($stmt->var))
+        ) {
+            if ($stmt_var_type->parent_nodes) {
+                $var_location = new CodeLocation($statements_analyzer->getSource(), $stmt->var);
+
+                $new_parent_node = DataFlowNode::getForAssignment('mixed-var-array-access', $var_location);
+
+                $data_flow_graph->addNode($new_parent_node);
+
+                foreach ($stmt_var_type->parent_nodes as $parent_node) {
+                    $data_flow_graph->addPath($parent_node, $new_parent_node, '=');
+
+                    $data_flow_graph->addPath(
+                        $parent_node,
+                        new DataFlowNode('variable-use', 'variable use', null),
+                        'variable-use'
+                    );
+                }
+
+                $stmt_var_type->parent_nodes = [
+                    $new_parent_node->id => $new_parent_node
+                ];
+            }
+        }
+
         if (!$array_access_type) {
             return Type::getMixed(
                 $type instanceof TEmpty
diff --git a/tests/UnusedVariableTest.php b/tests/UnusedVariableTest.php
index e91be3c4a..bff38743c 100644
--- a/tests/UnusedVariableTest.php
+++ b/tests/UnusedVariableTest.php
@@ -2275,6 +2275,21 @@ class UnusedVariableTest extends TestCase
                         $d += $l;
                     }',
             ],
+            'mixedArrayAccessMighBeObject' => [
+                '<?php
+                    function takesResults(array $arr) : void {
+                        /**
+                         * @psalm-suppress MixedAssignment
+                         */
+                        foreach ($arr as $item) {
+                            /**
+                             * @psalm-suppress MixedArrayAccess
+                             * @psalm-suppress MixedArrayAssignment
+                             */
+                            $item[0] = $item[1];
+                        }
+                    }'
+            ],
         ];
     }