Amend 39996524: Satisfy older cmake versions

[features.git] / CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8553efdf4a96f6c4b51c32b2406d4efdbfb9a1eb..3e5c613fffaa23a5f2f526ba733007ad74fccadd 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -6,13 +6,11 @@
 
 cmake_minimum_required(VERSION 3.1.0)
 
-set(CMAKE_CXX_STANDARD 20)
 set(GNUWIN32_DIR D:/LyX/lyx-unstable/lyx-windows-deps-msvc2017)
 set(LYX_USE_QT "QT5")
 set(LYX_REQUIRE_SPELLCHECK true)
 
 set(LYX_PROJECT LyX)
-
 # Instruct cmake to not use gnu extensions,
 # this prevents the mix of '-std=c++*' and '-std=gnu++*' flags
 set(CMAKE_CXX_EXTENSIONS OFF)
@@ -692,14 +690,33 @@ else()
        if(NOT LYX_QUIET)
                set(CMAKE_VERBOSE_MAKEFILE ON)
        endif()
-       set(LYX_CXX_FLAGS "-Wall -Wunused-parameter ${LYX_GCC11_MODE}${LYX_CXX_FLAGS}")
-       if(LYX_GCC11_MODE MATCHES "\\+\\+(14|11|98)")
+       if(LYX_GCC11_MODE MATCHES "\\+\\+([0-9][0-9])")
          # Thanks to Brad King <brad.king@kitware.com>
          # for the pointer to https://cmake.org/cmake/help/v3.6/variable/CMAKE_CXX_STANDARD.html
          # This allows us to use QT5.7 with recent g++ (version >= 4.9) compilers
          # and still use our own c++ extension tests
-         set(CMAKE_CXX_STANDARD ${CMAKE_MATCH_1})
-         message(STATUS "CMAKE_CXX_STANDARD set to ${CMAKE_CXX_STANDARD}")
+         set(std_num ${CMAKE_MATCH_1})
+         # Try to find a std-cxx-feature supported by this cmake version
+         while (std_num GREATER 0)
+           list(FIND CMAKE_CXX_COMPILE_FEATURES "cxx_std_${std_num}" stdfeature)
+           if (stdfeature GREATER -1)
+             set(CMAKE_CXX_STANDARD ${std_num})
+             break()
+           endif()
+           math(EXPR std_num "${std_num}-1")
+         endwhile()
+         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()
        if(LYX_STDLIB_DEBUG)
          set(LYX_CXX_FLAGS "${LYX_CXX_FLAGS} -D_GLIBCXX_DEBUG -D_GLIBCXX_DEBUG_PEDANTIC")
@@ -989,7 +1006,7 @@ if(WIN32)
                # -DPSAPI_VERSION=1 is not needed for mingw, since the mingw psapi.h
                # does not use it and always declares the vista compatible API.
                # If this ever changes then -DPSAPI_VERSION might be needed here as well.
-               add_definitions(-DWINVER=0x0600)
+               add_definitions(-DWINVER=0x0500)
        endif()
 endif()