[llvm] [DebugInfo] Swap 'Unit' and 'Type' positions in DISubprogram. (PR #96474)

[David Blaikie via llvm-commits]

dwblaikie wrote:

> In principle this LGTM, perhaps other reviewers could chime in though.

Yeah, bit janky - I don't totally object.

But alternatively: Could we remove the use/need for CurrentSourceLang? Guess it was added for fortran support, but perhaps we should've gone the toher way and weakened the checks? Just don't check for count/upperbound at all? (in visitDISubrange) 

Presumably LLVM can produce whatever DWARF we do for Fortran given such info, and do that for C++ too - even if it's incorrect for C++, maybe we move that to just be up to the IR generator to get that right?

https://github.com/llvm/llvm-project/pull/96474