Hi Elliot, thanks for the heads up:

On Mon, Aug 3, 2020 at 8:12 AM Elliott Sales de Andrade <quantum.analyst@gmail.com> wrote:
The build for ghc-cryptonite failed in the mass rebuild [1] and a
later rebuild by me [2], but only on s390x. The failure appears to be
LTO related. This doesn't appear to affect many other Haskell
packages. (I've found one seemingly-related failure in
ghc-haskell-src-exts [3].) Since it's Haskell, I'm using the standard
macros that should pass consistent flags, etc., so I'm not sure what
more information I can provide.

What happens is that ld.gold warns about mixed LTO/non-LTO:
Yeah this seems to be affecting profiling libraries (ghc-*-prof.s390x).

[2] https://koji.fedoraproject.org/koji/taskinfo?taskID=48408236

I opened https://bugzilla.redhat.com/show_bug.cgi?id=1863601 using the output from this build.

For now I am going to workaround this by disabling LTO for s390x Haskell packages in ghc-rpm-macros.
I think when we move to ghc-8.10 for F34 we can hopefully switch s390x to llvm10 which should make this problem go away.

Thanks, Jens