X-Git-Url: https://git.lyx.org/gitweb/?a=blobdiff_plain;f=CMakeLists.txt;h=3e5c613fffaa23a5f2f526ba733007ad74fccadd;hb=6869c3adffe2d938faa457d0bd457ce38dcc8afb;hp=90853559a82efc4eef4b400dd2ec9c247acb8d7a;hpb=968f7e8cacac366fe86466c1ed74a3cd5fe3387c;p=features.git

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 90853559a8..3e5c613fff 100644
--- 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")