[SOLVED] CMake works correctly on MSVC only with g++ option

Issue

When I remove -g and -O3 option from CMakeLists.txt my MSVC fail with lot of errors like:

libcpmt.lib(xwcscoll.obj) : error LNK2038: mismatch detected for 'RuntimeLibrary': value 'MT_StaticRelease' doesn't match value 'MD_DynamicRelease' in ExamplesTest.obj

I don't understand this strange bug because it's clearly write:

ignoring unknown option '-g' and ignoring unknown option '-O3'

CMakeLists.txt that works

cmake_minimum_required(VERSION 3.0)
project(NeuralNetwork CXX)
set(CMAKE_CXX_STANDARD 17)

if(NOT CMAKE_BUILD_TYPE)
  set(CMAKE_BUILD_TYPE Release)
endif()

if(MSVC)
  message("-- CMake run for msvc")
  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /NODEFAULTLIB:libboost_serialization-vc142-mt-x64-1_71.lib")
  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /NODEFAULTLIB:libboost_serialization-vc142-mt-gd-x64-1_71.lib")
  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /NODEFAULTLIB:libboost_serialization-vc142-mt-sgd-x64-1_71.lib")
  set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} /Od /Zi")
  set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} /O2")
endif()

set(CMAKE_CXX_FLAGS_DEBUG "-g")
set(CMAKE_CXX_FLAGS_RELEASE "-O3")

add_subdirectory(src)
add_subdirectory(tests)

CMakeLists.txt that doesn't work

cmake_minimum_required(VERSION 3.0)
project(NeuralNetwork CXX)
set(CMAKE_CXX_STANDARD 17)

if(NOT CMAKE_BUILD_TYPE)
  set(CMAKE_BUILD_TYPE Release)
endif()

if(MSVC)
  message("-- CMake run for msvc")
  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /NODEFAULTLIB:libboost_serialization-vc142-mt-x64-1_71.lib")
  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /NODEFAULTLIB:libboost_serialization-vc142-mt-gd-x64-1_71.lib")
  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /NODEFAULTLIB:libboost_serialization-vc142-mt-sgd-x64-1_71.lib")
  set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} /Od /Zi")
  set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} /O2")
else()
  message("-- CMake run for g++")
  set(CMAKE_CXX_FLAGS_DEBUG "-g")
  set(CMAKE_CXX_FLAGS_RELEASE "-O3")
endif()

add_subdirectory(src)
add_subdirectory(tests)

Can you explain me what did CMake as extra-step in the working case?

Edit: I have tested, rebuilt, and cleaned several times, I am almost sure that the error comes from there.

Solution

It's because set(CMAKE_CXX_FLAGS_DEBUG "-g") and set(CMAKE_CXX_FLAGS_RELEASE "-O3") overload existing setting. I just set a value for CMAKE_CXX_FLAGS_RELEASE and CMAKE_CXX_FLAGS_RELEASE when I'm compile with MSVC.

if(MSVC)
  message("-- CMake run for msvc")
  set(CMAKE_CXX_FLAGS_RELEASE "/O2 /MT")
  set(CMAKE_CXX_FLAGS_DEBUG "/Od /Zi /MTd")
  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /NODEFAULTLIB:libboost_serialization-vc142-mt-x64-1_71.lib")
  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /NODEFAULTLIB:libboost_serialization-vc142-mt-s-x64-1_71.lib")
  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /NODEFAULTLIB:libboost_serialization-vc142-mt-gd-x64-1_71.lib")
  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /NODEFAULTLIB:libboost_serialization-vc142-mt-sgd-x64-1_71.lib")
else()
  #set(CMAKE_CXX_FLAGS "-Wall -Wextra")
  set(CMAKE_CXX_FLAGS_DEBUG "-g")
  set(CMAKE_CXX_FLAGS_RELEASE "-O3")
endif(

Answered By - Matthieu H