GHC 9.2.7 on FreeBSD - HSC2HS_EXTRA issue

[Martin Baulig]

Hello,

I am a FreeBSD user, running FreeBSD 13.1 with Clang 13 and GCC 12.2, and still fairly new to the Haskell Platform.

When I tried to upgrade a hobby project to Stackage's latest LTS 20.15, I realized that neither the GHC 9.2.6 nor
the GHC 9.2.7 binary packages from GHCUP work anymore.

There are two issues - and I wrote a detailed article about my investigation on Medium:
https://medium.com/@martin.baulig/ghc-9-2-7-on-freebsd-22afab71c715

The first one is a trivial one-line change - in hadrian/src/Rules/BinaryDist.hs, we need to change

> ( "HSC2HS_EXTRA=\"" <> unwords ccArgs <> unwords ldFlags <> "\""

into

> ( "HSC2HS_EXTRA=\"" <> unwords (ccArgs <> ldFlags) <> "\""

Otherwise, this will break when both ccArgs and ldFlags are non-empty:

> HSC2HS_EXTRA="--cflag=--target=x86_64-portbld-freebsd--lflag=--target=x86_64-portbld-freebsd --lflag=-fuse-ld=lld"

Unfortunately, this is not quite it just yet.

The problem is that Clang supports the --target= argument, but GCC does not - and it looks like Cabal insists on always
invoking hsc2hs with an explicit --cc= argument.

Overriding that in ~/.cabal/config doesn't work either - because then Cabal passes "-pgmc /usr/bin/cc" to GHC, but no
"-pgma" and GHC tries to invoke GCC for assembling with a Clang-only argument.

I am a bit lost here now about what the correct path forward is, but would very much like to help fixing this problem,
so I created an account on gitlab.haskell.org to report this issue, but got a message saying that it is awaiting admin
approval. Looking a bit further in the documentation for new contributors, I saw a comment suggesting I should
post on this mailing list and ask for approval. Could an admin please have a look at that? My user name is my last
name in lowercase, baulig.

Looking forward to hear back from you,

Martin
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/ghc-devs/attachments/20230320/d21e0f79/attachment.html>