While trying to build the haskell-ide-engine project (https://github.com/haskell/haskell-ide-engine) on Windows 10, using my system global install of ghc-8.6.3, the process seems to hang while building fclabels-2.0.3.3. (I followed the project build instructions, using command

.\build-all.ps1 8.6.3

in the project root folder, which uses stack resolver lts-13.0 and ghc-8.6.3.) I get the same result (process never finishes) trying to build fclabels by itself:

stack install fclabels --stack-yaml .\stack-8.6.3.yaml

in the haskell-ide-engine root folder. To simplify, I tried to build fclabels with cabal install (cabal-2.4.1.0) in my home folder (where there are no .cabal files present):

cabal -v -j1 v2-install fclabels

Output is attached. The process hangs at compiling Data.Label.Base source to object file. Windows task manager shows ghc working merrily away (overnight, on my first attempt) without finishing. On the other hand, if I run

stack install fclabels --stack-yaml .\stack-8.4.4.yaml

in the haskell-ide-engine root folder, which uses stack resolver lts-12.20 and ghc-8.4.4, fclabels-2.0.3.3 builds successfully. Because of the complexity of cabal and stack package management I don't know where to pin the blame, perhaps it's on my own system setup, hence don't know where/whether to file a bug report. Regards, Graham