stack setup --upgrade-cabal breaks GHC relocatability on Windows

[mwu-tow]

I have a custom build of GHC 7.8.4. Normally I can move it between machines on Windows, as the GHC distribution is relocable. However, in order to build my projects with stack, I need to do the --upgrade-cabal step. The stack installs then a new Cabal 1.22 library into the global package database that goes with compiler. However, the installed Cabal package is not relocable and such "patched" GHC installation can't be moved to a different location anymore.

Tha file describing package in database (GHC_DIR\lib\package.conf.d\Cabal-1.22.4.0-795f2274b99f2bda17fbad366d93efef.conf in my case) uses absolute paths, like:

library-dirs: C:\Users\mwurb_000\AppData\Local\Programs\stack\x86_64-windows\ghc-7.8.4\new-cabal\1.22.4.0\lib\x86_64-windows-ghc-7.8.4\Cabal-1.22.4.0

If I manually replace such absolute paths with the relative ones using the $topdir (like all other packages in the database), everything becomes relocable again. Could stack set relative paths for the Cabal package description it installs? The following fixes the problem for me:

library-dirs: $topdir\..\new-cabal\1.22.4.0\lib\x86_64-windows-ghc-7.8.4\Cabal-1.22.4.0

[snoyberg]

AFAIK, Stack cannot control this, it would need to be a change to the Cabal
library. If I'm mistaken and there is a way to configure in this way, a PR
would certainly be accepted (presuming it doesn't break other OSes).

On Wed, Oct 14, 2015 at 1:09 PM, Michał Wawrzyniec Urbańczyk <
[email protected]> wrote:

I have a custom build of GHC 7.8.4. Normally I can move it between
machines on Windows, as the GHC distribution is relocable. However, in
order to build my projects with stack, I need to do the --upgrade-cabal
step. The stack installs then a new Cabal 1.22 library into the global
package database that goes with compiler. However, the installed Cabal
package is not relocable and such "patched" GHC installation can't be moved
to a different location anymore.

Tha file describing package in database
(GHC_DIR\lib\package.conf.d\Cabal-1.22.4.0-795f2274b99f2bda17fbad366d93efef.conf
in my case) uses absolute paths, like:

library-dirs: C:\Users\mwurb_000\AppData\Local\Programs\stack\x86_64-windows\ghc-7.8.4\new-cabal\1.22.4.0\lib\x86_64-windows-ghc-7.8.4\Cabal-1.22.4.0

If I manually replace such absolute paths with the relative ones using the
$topdir (like all other packages in the database), everything becomes
relocable again. Could stack set relative paths for the Cabal package
description it installs? The following fixes the problem for me:

library-dirs: $topdir..\new-cabal\1.22.4.0\lib\x86_64-windows-ghc-7.8.4\Cabal-1.22.4.0

—
Reply to this email directly or view it on GitHub
#1159.

[mwu-tow]

If it is an external problem, then fixing it on the stack side is probably more trouble than it is worth. Having manually corrected the paths to the new-cabal I can simply copy the patched installation between computers, so the issue is not a big problem for me. [I guess I could even teach stack to download it automatically]

I did some more searching and perhaps this is already fixed in the Cabal: haskell/cabal#2255 — I haven't tested it but it looks that cabal-installed packages will use relative paths.

I guess I'll close the issue in such case.