Meaning of -i and -hidir

[Oleg Grenrus]

This looks like a bug.

-hidir documentation says

> Redirects all generated interface files into ⟨dir⟩, instead of the
default.
> Please also note that when doing incremental compilation (by ghc
--make or ghc -c), this directory is where GHC looks into to find
interface files.

And documentation for -i doesn't mention looking for interface files.

So by doing

% ghc -dynamic-too -c lib/Lib.hs -odir odir -hidir hidir_Lib
% ghc -dynamic-too -c Main.hs -odir odir -hidir hidir_Main -ihidir_Lib
1
% ghc odir/Lib.o odir/Main.o -o Demo                                 
% ./Demo                                                             
True

everything compiles, TH is run, and demo works. The result files are

% find .
.
./Demo
./Main.hs
./hidir_Main
./hidir_Main/Main.dyn_hi
./hidir_Main/Main.hi
./odir
./odir/Main.dyn_o
./odir/Main.o
./odir/Lib.dyn_o
./odir/Lib.o
./hidir_Lib
./hidir_Lib/Lib.dyn_hi
./hidir_Lib/Lib.hi
./lib
./lib/Lib.hs

---

The confusing error is caused by Lib module in libiserv:
https://hackage.haskell.org/package/libiserv
which GHC picks!

If we rename your Lib module to Library, the error is way better: Could
not find module ‘Library’

I also tried using same -hidir when compiling both modules, then GHC
still cannot find the Library interface, even the documentation says it
should.

Please open a GHC issue at https://gitlab.haskell.org/ghc/ghc/-/issues

- Oleg

On 22.10.2021 19.16, Domínguez, Facundo wrote:
> 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 |])
>
> _______________________________________________
> ghc-devs mailing list
> ghc-devs at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/ghc-devs/attachments/20211023/82f5f98e/attachment.html>