[clang] [llvm] [libclang][Cygwin] Provide unversioned DLL file alongside versioned one (PR #147132)

[Tomohiro Kashiwada via cfe-commits]

kikairoya wrote:

Thanks again.

> I got pretty strong negative feedback on including these symlinks at all.

I didn’t expect such a strong reaction... I'm really sorry for dragging you into it.

> I've tried this with msys2 (where symlinks are really copies and `LLVM_USE_SYMLINKS=OFF` and got some (non-fatal) errors during install

The problem seems to be common to `LLVM_USE_SYMLINKS=OFF`. Each action in one component can't declare dependencies with other actions and they are executed in registration order.

The installation action of `msys-LLVM-20.1.8.dll` and `msys-LLVM.dll` are registered here:
https://github.com/llvm/llvm-project/blob/34359cf21b444047464d7e607686ec19bfbb25de/llvm/cmake/modules/AddLLVM.cmake#L754-L757
before registering the action of `msys-LLVM-20.dll` at here:
https://github.com/llvm/llvm-project/blob/34359cf21b444047464d7e607686ec19bfbb25de/llvm/cmake/modules/AddLLVM.cmake#L983-L987
thus, the former installation actions try to copy the source before it is installed.

I don't think anyone actually uses `LLVM_USE_SYMLINKS=OFF` except MSYS, so this inversion may not need to be addressed if this PR is dropped.


https://github.com/llvm/llvm-project/pull/147132