Dear devs, I'm confused about the meaning of -hidir and -i. Here's my experiment with both ghc-9.2.0 and ghc-8.10.4.
$ find ./Main.hs ./lib/Lib.hs
$ ghc -dynamic-too -c lib/Lib.hs -odir odir -hidir hidir_Lib
$ ghc -dynamic-too -c Main.hs -odir odir -ihidir_Lib -hidir hidir_Main
Main.hs:3:1: error: Bad interface file: hidir_Main/Lib.hi hidir_Main/Lib.hi: openBinaryFile: does not exist (No such file or directory) | 3 | import Lib | ^^^^^^^^^^
If I only use -hidir, it still fails with another error
$ ghc -dynamic-too -c Main.hs -odir odir -hidir hidir_Lib
Main.hs:7:29: error: Variable not in scope: f | 7 | main = print $(runIO (print f) >> [| True |]) | ^
If I use both -i and -hidir pointing to the same folder, then it works!
$ ghc -dynamic-too -c Main.hs -odir odir -ihidir_Lib -hidir hidir_Lib
Now, is this behavior a bug or a feature? And if it is a bug, what is the expected behavior? Programs copied below. Thank you! Facundo
$ cat lib/Lib.hs module Lib where
f :: Int f = 1
$ cat Main.hs {-# LANGUAGE TemplateHaskell #-}
import Lib import Language.Haskell.TH http://language.haskell.th/
main :: IO () main = print $(runIO (print f) >> [| True |])