We have a better alternative to FilePath now. See: https://hasufell.github.io/posts/2022-06-29-fixing-haskell-filepaths.html

What we should do:

1. Change NormalizedFilePath to NormalizedOsPath after the issue in lsp to support OsPath Migrate to OsPath lsp#445 is solved. Profiling it to make sure the performance improves.
2. Change other usages of FilePath to OsPath

However, this can not be done until ghc-9.6 is released (ships the new filepath library), or all ghc shipped libraries are available on Hackage.

Many GHC bundled libraries do not have new versions released to Hackage (for example ghci and hpc, their versions on hackage is very old). Thus, cabal solver fails if I add filepath ^>= 1.4.100.0 to a project that depends on ghc, which then depends on ghci. The installed ghci links against filepath-1.4.2.2 in this case, and cabal can not rebuild a ghci with filepath ^>= 1.4.100.0, as the source code is not found on hackage.