Amend 39996524: Satisfy older cmake versions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3840cc95857a43fc4a66ad8db03f7cdb87cb7e2a..3e5c613fffaa23a5f2f526ba733007ad74fccadd 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -699,15 +699,22 @@ else()
          # Try to find a std-cxx-feature supported by this cmake version
          while (std_num GREATER 0)
            list(FIND CMAKE_CXX_COMPILE_FEATURES "cxx_std_${std_num}" stdfeature)
-           if (stdfeature GREATER_EQUAL 0)
+           if (stdfeature GREATER -1)
              set(CMAKE_CXX_STANDARD ${std_num})
              break()
            endif()
            math(EXPR std_num "${std_num}-1")
          endwhile()
-
-         message(STATUS "CMAKE_CXX_STANDARD set to ${CMAKE_CXX_STANDARD}")
-         set(LYX_CXX_FLAGS "-Wall -Wunused-parameter ${LYX_CXX_FLAGS}")
+         message(STATUS "std_num = ${std_num}")
+         if (std_num EQUAL 0)
+           # not found appropriate feature
+           # so we use LYX_GCC11_MODE
+           set(LYX_CXX_FLAGS "-Wall -Wunused-parameter ${LYX_GCC11_MODE}${LYX_CXX_FLAGS}")
+         else()
+           message(STATUS "CMAKE_CXX_STANDARD set to ${CMAKE_CXX_STANDARD}")
+           set(LYX_CXX_FLAGS "-Wall -Wunused-parameter ${LYX_CXX_FLAGS}")
+         endif()
+         message(STATUS "Setting LYX_CXX_FLAGS to ${LYX_CXX_FLAGS}")
        else()
          set(LYX_CXX_FLAGS "-Wall -Wunused-parameter ${LYX_GCC11_MODE}${LYX_CXX_FLAGS}")
        endif()

diff --git a/development/cmake/modules/FindCXX11Compiler.cmake b/development/cmake/modules/FindCXX11Compiler.cmake
index 96b72eb33fad6b990afc56ae116a43a399e22f9e..7f22f596b867f35b80b88a41380c85483e739865 100644 (file)
--- a/development/cmake/modules/FindCXX11Compiler.cmake
+++ b/development/cmake/modules/FindCXX11Compiler.cmake
@@ -54,6 +54,7 @@ else()
       endif()
     else()
       set(CXX11_FLAG_CANDIDATES
+        "--std=c++20"
         "--std=c++17"
         "--std=c++14"
         "--std=c++11"