cmake invalid numeric argument '/Wextra'

cmake

Solution

Your CMakeLists.txt defines compile flag -Wextra for GCC and then CMake tried to use that on cl (the Microsoft compiler) too. Fix the CMakeLists.txt so that it tests for compiler before setting warning flags, i.e.

# Set default compile flags for GCC
if(CMAKE_COMPILER_IS_GNUCXX)
    message(STATUS "GCC detected, adding compile flags")
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++98 -pedantic -Wall -Wextra")
endif(CMAKE_COMPILER_IS_GNUCXX)

Problem

Windows XP Pro 32bit Visual studio 2008 VC Express edition. I have installed cmake and created the CMakeLists.txt and I want to cross-platform for Linux/windows. Everything works ok for running on linux. So I copied my source directory as I am doing out of source building to my windows xp machine. I used the cmake-GUI to configure/generate the solution files. Everything ok there. However, when I opened the solution file and selected build from menu I got the following error. ``` cl : Command line error D8021 : invalid numeric argument '/Wextra' ``` Not sure really where to start looking to solve this error. If any one can point me in the right direction. Many thanks for any suggestions,

Original source