Compile with /MT instead of /MD using CMake

Question

I'm using CMake on windows with the Windows SDK and NMake Makefiles.

By default it compiles with the /MD compiler switch.

How can I change it to compile with the /MT switch instead?

Answer 1

You can modify the CMAKE_CXX_FLAGS_<Build Type> and/or CMAKE_C_FLAGS_<Build Type> variables:

set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} /MT")
set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} /MTd")

If your CMake flags already contain /MD, you can ensure that the above commands are executed after the point at which /MD is inserted (the later addition of /MT overrides the conflicting existing option), or you can set the flags from scratch:

set(CMAKE_CXX_FLAGS_RELEASE "/MT")
set(CMAKE_CXX_FLAGS_DEBUG "/MTd")

Or alternatively, you could replace the existing /MD and /MDd values with /MT and /MTd respectively by doing something like:

set(CompilerFlags
        CMAKE_CXX_FLAGS
        CMAKE_CXX_FLAGS_DEBUG
        CMAKE_CXX_FLAGS_RELEASE
        CMAKE_C_FLAGS
        CMAKE_C_FLAGS_DEBUG
        CMAKE_C_FLAGS_RELEASE
        )
foreach(CompilerFlag ${CompilerFlags})
  string(REPLACE "/MD" "/MT" ${CompilerFlag} "${${CompilerFlag}}")
endforeach()