Recently[1] the hadrian hie-bios script was reworked to work on Windows too, and in the process the file was renamed from hie-bios to hie-bios.bat

For me this broke HLS in emacs, because the new file does not have the executable flag set on my Linux checkout.

Doing 

  chmod +x hadrian/hie-bios.bat 

restores full functionality

Alan

[1] https://gitlab.haskell.org/ghc/ghc/-/commit/9df24b7e5fa8e76c01270ce1e708ab4cbcefacd1