skip with concat

Author: samsonasik

rules-tests/DowngradePhp80/Rector/FuncCall/DowngradeSubstrFalsyRector/Fixture/skip_with_concat.php.inc.inc

@@ -0,0 +1,14 @@
+<?php
+
+namespace Rector\Tests\DowngradePhp80\Rector\FuncCall\DowngradeSubstrFalsyRector\Fixture;
+
+/**
+ * falsy concat become empty string
+ */
+class SkipWithConcat
+{
+    public function run()
+    {
+        return substr('a', 2) . substr('b', 2);
+    }
+}

rules/DowngradePhp80/Rector/FuncCall/DowngradeSubstrFalsyRector.php

@@ -7,6 +7,7 @@
 use PhpParser\Node;
 use PhpParser\Node\Arg;
 use PhpParser\Node\Expr;
+use PhpParser\Node\Expr\BinaryOp\Concat;
 use PhpParser\Node\Expr\BinaryOp\Identical;
 use PhpParser\Node\Expr\BooleanNot;
 use PhpParser\Node\Expr\Cast;
@@ -50,11 +51,11 @@ public function getRuleDefinition(): RuleDefinition
      */
     public function getNodeTypes(): array
     {
-        return [Cast::class, Empty_::class, BooleanNot::class, Ternary::class, Identical::class, FuncCall::class];
+        return [Cast::class, Empty_::class, BooleanNot::class, Ternary::class, Identical::class, Concat::class, FuncCall::class];
     }
 
     /**
-     * @param Cast|Empty_|BooleanNot|Ternary|Identical|FuncCall $node
+     * @param Cast|Empty_|BooleanNot|Ternary|Identical|Concat|FuncCall $node
      */
     public function refactor(Node $node): ?Node
     {
@@ -71,6 +72,12 @@ public function refactor(Node $node): ?Node
             return null;
         }
 
+        if ($node instanceof Concat) {
+            $node->left->setAttribute(self::IS_UNCASTABLE, true);
+            $node->right->setAttribute(self::IS_UNCASTABLE, true);
+            return null;
+        }
+
         if ($node instanceof Identical) {
             if ($this->valueResolver->isFalse($node->left)) {
                 $node->right->setAttribute(self::IS_UNCASTABLE, true);