[clang] [llvm] [ARM] Emit an error when the hard-float ABI is enabled but can't be used. (PR #111334)

[Peter Smith via cfe-commits]

https://github.com/smithp35 commented:

I'm not yet convinced that llvm is the right place for this error message. There's quite a lot of test changes that I presume needed to make and at least the LTO use case looks like we don't want to require extra information. I'd also prefer this to be a front-end error/warning as this is a front-end/source-level mistake, with better diagnostic control options available.

I think if it is implemented in llvm then it will need to use the per-function subtarget to not risk fallout with LTO builds.

Apologies I'm probably not particularly enthusiastic about the approach. I've not worked in this area for some time so I'm happy for other reviewer's opinions to take precedence.

https://github.com/llvm/llvm-project/pull/111334