https://gitlab.cern.ch/hepmc/HepMC/-/merge_requests/16
From 1bb90ccda81187c71c1e234e3d55390684ce1041 Mon Sep 17 00:00:00 2001
From: Giulio Eulisse <10544+ktf@users.noreply.github.com>
Date: Tue, 6 Jan 2026 13:39:58 +0100
Subject: [PATCH] Add support for CMake 4

Upstream deprecated support for CMake <= 3.5.

See https://cmake.org/cmake/help/latest/release/4.0.html#deprecated-and-removed-features
---
 CMakeLists.txt | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7b2dd93..6d7e807 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -13,8 +13,8 @@
 # which matches the default HepMC autoconf flags
 #------------------------------------------------------------------------------
 
-# use cmake 2.6 or later
-cmake_minimum_required (VERSION 2.6)
+# use cmake 3.16 or later
+cmake_minimum_required (VERSION 3.16)

 # project name and version
 project(HepMC)
-- 
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