From 25f78b5d54307c8dd35951bdba902c37e2d2ab02 Mon Sep 17 00:00:00 2001
From: orklah <ronan_morin@hotmail.com>
Date: Thu, 16 Sep 2021 19:33:57 +0200
Subject: [PATCH] refine Mod with positives everywhere

---
 .../Expression/BinaryOp/ArithmeticOpAnalyzer.php         | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ArithmeticOpAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ArithmeticOpAnalyzer.php
index 0ff97b902..0277e566c 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ArithmeticOpAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/BinaryOp/ArithmeticOpAnalyzer.php
@@ -1326,7 +1326,14 @@ class ArithmeticOpAnalyzer
             }
         } elseif ($right_type_part->isPositive()) {
             if ($left_type_part->isPositiveOrZero()) {
-                $new_result_type = new Type\Union([new TIntRange(0, null)]);
+                if ($left_type_part->max_bound !== null) {
+                    //we now that the result will be a range between 0 and $left->max - 1
+                    $new_result_type = new Type\Union(
+                        [new TIntRange(0, $left_type_part->max_bound - 1)]
+                    );
+                } else {
+                    $new_result_type = new Type\Union([new TIntRange(0, null)]);
+                }
             } elseif ($left_type_part->isNegativeOrZero()) {
                 $new_result_type = new Type\Union([new TIntRange(null, 0)]);
             } else {