[LyX/master] Cmake build:Amend 44bbd0b0 and 22f59925

[Kornel Benko]

commit 6f2cd26103d0d59fd76184fd76af89cb8817ad4f
Author: Kornel Benko <kor...@lyx.org>
Date:   Thu Jun 13 09:18:40 2019 +0200

    Cmake build:Amend 44bbd0b0 and 22f59925
    
    44bbd0b0: Get full version of gcc
    22f59925: Remove support for gcc 4.6
    
    Also Remove support for msvc without STD_REGEX
---
 CMakeLists.txt |   18 +++++++++++-------
 1 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5118560..acaad7c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -283,15 +283,17 @@ if(UNIX OR MINGW)
            set(LYX_USE_STD_REGEX 0)
          endif()
        else()
-         execute_process(COMMAND ${CMAKE_CXX_COMPILER} -dumpversion 
OUTPUT_VARIABLE GCC_VERSION OUTPUT_STRIP_TRAILING_WHITESPACE)
+         execute_process(COMMAND ${CMAKE_CXX_COMPILER} -dumpfullversion 
OUTPUT_VARIABLE GCC_VERSION ERROR_VARIABLE _error RESULT_VARIABLE _err 
OUTPUT_STRIP_TRAILING_WHITESPACE)
+         #message(STATUS "dumpfullversion: error = ${_error}, result = 
${_err}")
+         if (_err)
+           # previous check failed, try again with _old_ parameter
+           execute_process(COMMAND ${CMAKE_CXX_COMPILER} -dumpversion 
OUTPUT_VARIABLE GCC_VERSION ERROR_VARIABLE _error RESULT_VARIABLE _err 
OUTPUT_STRIP_TRAILING_WHITESPACE)
+           #message(STATUS "dumpversion: error = ${_error}, result = ${_err}")
+         endif()
          message(STATUS "Using GCC version ${GCC_VERSION}")
          if(GCC_VERSION VERSION_LESS 4.9)
-                 if(GCC_VERSION VERSION_LESS 4.6)
-                         message(FATAL_ERROR "gcc >= 4.6 is required.")
-                 endif()
-                 # <regex> in gcc is unusable in versions less than 4.9.0
-                 # see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53631
-                 set(LYX_USE_STD_REGEX 0)
+                 # Drop support for gcc versions prior to 4.9
+                 message(FATAL_ERROR "gcc >= 4.9 is required.")
          else()
                  set(LYX_USE_STD_REGEX 1)
          endif()
@@ -299,6 +301,8 @@ if(UNIX OR MINGW)
        set(LYX_GCC11_MODE "${CXX11_FLAG}")
 else()
        if(MSVC_VERSION LESS 1915)
+               # Drop support for msvc versions prior to 1915
+               message(FATAL_ERROR "msvc >= 1915 is required.")
                set(LYX_USE_STD_REGEX 0)
        else()
                set(LYX_USE_STD_REGEX 1)