# CMP0104

Initialize `CMAKE_CUDA_ARCHITECTURES` when `CMAKE_CUDA_COMPILER_ID` is `NVIDIA`. Raise an error if `CUDA_ARCHITECTURES` is empty.

`CMAKE_CUDA_ARCHITECTURES` introduced in CMake 3.18 is used to initialize `CUDA_ARCHITECTURES`, which passes correct code generation flags to the CUDA compiler.

Previous to this users had to manually specify the code generation flags. This policy is for backwards compatibility with manually specifying code generation flags.

The `OLD` behavior for this policy is to not initialize `CMAKE_CUDA_ARCHITECTURES` when `CMAKE_CUDA_COMPILER_ID` is `NVIDIA`. Empty `CUDA_ARCHITECTURES` is allowed.

The `NEW` behavior of this policy is to initialize `CMAKE_CUDA_ARCHITECTURES` when `CMAKE_CUDA_COMPILER_ID` is `NVIDIA` and raise an error if `CUDA_ARCHITECTURES` is empty during generation.

If `CUDA_ARCHITECTURES` is set to a false value no architectures flags are passed to the compiler. This is intended to support packagers and the rare cases where full control over the passed flags is required.

This policy was introduced in CMake version 3.18. CMake version 3.18.0-rc4 warns when the policy is not set and uses `OLD` behavior. Use the `cmake_policy()` command to set it to `OLD` or `NEW` explicitly.

Note

The `OLD` behavior of a policy is `deprecated by definition` and may be removed in a future version of CMake.

## Examples

    set_property(TARGET tgt PROPERTY CUDA_ARCHITECTURES 35 50 72)

Generates code for real and virtual architectures `30`, `50` and `72`.

    set_property(TARGET tgt PROPERTY CUDA_ARCHITECTURES 70-real 72-virtual)

Generates code for real architecture `70` and virtual architecture `72`.

    set_property(TARGET tgt PROPERTY CUDA_ARCHITECTURES OFF)

CMake will not pass any architecture flags to the compiler.