Re: can't move to latest version of llvm on ghc 9.12.2

1 Apr 2025

      Looking at https://gitlab.haskell.org/ghc/ghc/-/issues/25011 it seems
the desire was to fail with a proper error when LLVM was not found at all.

To me failing when the llvm version is too new seems like a unintended
side effect of fixing the former.

I agree that simply warning and trying anway is the better default. A
ticket would be appreciated!

Am 01/04/2025 um 19:05 schrieb George Colpitts:
...
I was trying to find out if it works but I ran into the problem I
described. Yes, there were a few years where the latest version didn't
work but in many years it did. ghc used to give a warning, this is an
unsupported version but we'll try it anyways. I would like to
return to that.
In any case I believe ghc dev should test to see if it works and if so
use it in HEAD. If it doesn't work than we should file a bug and fix
it. In the past we got a few versions behind llvm. I think we want to
be on the latest version available for each new release if possible.
The earlier we look into this the more chance we have to succeed at that.
On Tue, Apr 1, 2025 at 1:27 PM Brandon Allbery 
wrote:
Have you demonstrated that it works? IIRC the current behavior is
    because some LLVM version (16, IIRC) didn't work with GHC (threw
    errors from opt, I think).
On Tue, Apr 1, 2025 at 10:49 AM George Colpitts
     wrote:
llvm 20 is out but unlike in earlier versions of ghc moving to
        it means you can no longer use llvm:
compiling:
ghc -fllvm hello.hs
            Loaded package environment from
            /Users/avie/.ghc/aarch64-darwin-9.12.2/environments/default
            [1 of 2] Compiling Main             ( hello.hs, hello.o )
            <no location info>: error: [GHC-66599]
              GHC was not configured with a supported LLVM toolchain
              Make sure you have installed LLVM between [13 and 20)
            and reinstall GHC to make -fllvm work
from configure:
configure: We only support llvm 13 upto 20 (non-inclusive)
            (found 20.1.1).
Can we move to llvm 20 on HEAD and can we revert to the old
        behavior on ghc 9.12.3?
Should I file an ER?
Thanks
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--
    brandon s allbery kf8nh
    allbery.b@gmail.com
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Re: can't move to latest version of llvm on ghc 9.12.2

Andreas Klebinger