From 8db8708d75fc33dec43be20d28298304d91f4963 Mon Sep 17 00:00:00 2001
From: Dmitri Naumov <dmitri.naumov@ufz.de>
Date: Thu, 22 Aug 2024 15:11:21 +0200
Subject: [PATCH] [MeL/IO] Explicit checked material ids conversion

The legacy reader is designed for unsigned type of material ids,
but current implementation works on signed integers.

This fixes a compilation warning.
---
 MeshLib/IO/Legacy/MeshIO.cpp | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/MeshLib/IO/Legacy/MeshIO.cpp b/MeshLib/IO/Legacy/MeshIO.cpp
index faf2e8b7f3d..898d2741049 100644
--- a/MeshLib/IO/Legacy/MeshIO.cpp
+++ b/MeshLib/IO/Legacy/MeshIO.cpp
@@ -29,15 +29,20 @@
 
 namespace
 {
-std::size_t readMaterialID(std::istream& in)
+int readMaterialID(std::istream& in)
 {
     unsigned index;
     unsigned material_id;
-    if (!(in >> index >> material_id))
+
+    if (!(in >> index >> material_id) ||
+        material_id > static_cast<unsigned>(std::numeric_limits<int>::max()))
     {
-        return std::numeric_limits<std::size_t>::max();
+        // If read incorrectly or the material_id is not safely convertible to
+        // int.
+        return std::numeric_limits<int>::max();
     }
-    return material_id;
+    // Safe conversion was checked above.
+    return static_cast<int>(material_id);
 }
 
 MeshLib::Element* readElement(std::istream& in,
@@ -289,7 +294,7 @@ MeshLib::Mesh* MeshIO::loadMeshFromFile(const std::string& file_name)
     {
         std::vector<MeshLib::Node*> nodes;
         std::vector<MeshLib::Element*> elements;
-        std::vector<std::size_t> materials;
+        std::vector<int> materials;
 
         while (!in.eof())
         {