CUDA: Fix issuing error if default architecture detection fails

We require CUDA_ARCHITECTURES to be set for targets (see CMP0104). If not set
anything after compiler detection such as ABI detection will fail to generate.
This means we need to error if CMAKE_CUDA_ARCHITECTURES is not set to a valid
value as a result of compiler detection.

Currently we fail to issue the error if compiler detection failed and the ID is
unset. In such a case we won't define detected_architecture making the code
responsible for the error unreachable.

Simplify the detection of architectures used during compiler detection by
always detecting all of them, which enables us to simply the check in the
"default to compiler" path if CMAKE_CUDA_ARCHITECTURES is empty.
As a result we need to move the error checking and CMAKE_CUDA_ARCHITECTURES=OFF
handling fully into the default path thus simplifying the code and unifying the
code paths for NVCC and CUDA.
This also happens to fix:
1. CMAKE_CUDA_ARCHITECTURES=OFF on Clang.
2. A theoretical issue of a compiler defaulting to multiple architectures.

I've additionally added printing of the compiler output along the error to
better reveal possible underlying compiler/system configuration issues.

Fixes #23010.

0 files changed, 0 insertions, 0 deletions