How to build x86 and/or x64 on Windows from command line with CMAKE?

Question

One way to get cmake to build x86 on Windows with Visual Studio is like so:

1. Start Visual Studio Command prompt for x86
2. Run cmake: cmake -G "NMake Makefiles" \path_to_source\
3. nmake

One way to get cmake to build x64 on Windows with Visual Studio is like so:

1. Start Visual Studio Command prompt for x64
2. Run cmake: cmake -G "NMake Makefiles" \path_to_source\
3. nmake

Using Cmake, how do I compile either or both architectures? (like how Visual Studio does it from in the IDE)

Answer 1

This cannot be done with CMake. You have to generate two separate build folders. One for the x86 NMake build and one for the x64 NMake build. You cannot generate a single Visual Studio project covering both architectures with CMake either.

To build Visual Studio projects from the command line for both 32-bit and 64-bit without starting a Visual Studio command prompt, use the regular Visual Studio generators:

mkdir build32 & pushd build32
cmake -G "Visual Studio 12 2013" \path_to_source\
popd
mkdir build64 & pushd build64
cmake -G "Visual Studio 12 2013 Win64" \path_to_source\
popd
cmake --build build32 --config Release
cmake --build build64 --config Release

CMake generated projects that use one of the Visual Studio generators can be built from the command line with using the option --build followed by the build directory. The --config options specifies the build configuration.

Answer 2

try use CMAKE_GENERATOR_PLATFORM

e.g.

// x86
cmake -DCMAKE_GENERATOR_PLATFORM=x86 . 

// x64
cmake -DCMAKE_GENERATOR_PLATFORM=x64 . 

Answer 3

There is the -A switch

cmake -G "Visual Studio 16 2019" -A Win32
cmake -G "Visual Studio 16 2019" -A x64

https://cmake.org/cmake/help/v3.16/generator/Visual%20Studio%2016%202019.html#platform-selection

  -A <platform-name>           = Specify platform name if supported by
                                 generator.