diff -rupN --no-dereference gmsh-4.8.4-source/CMakeLists.txt gmsh-4.8.4-source-new/CMakeLists.txt
--- gmsh-4.8.4-source/CMakeLists.txt	2021-04-29 15:05:54.751037956 +0200
+++ gmsh-4.8.4-source-new/CMakeLists.txt	2021-04-29 15:05:54.754037956 +0200
@@ -17,7 +17,7 @@ endif()
 project(gmsh CXX C)
 
 # require C++11 and request C99
-set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD 14)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_C_STANDARD 99)