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

[George Colpitts]

The obvious workaround is to change the configure file to

LlvmMaxVersion=21


then rerun configure and sudo make install.

I did that and smoke tested llvm 20.15 and it seems to work fine. In case
anybody else is interested in testing llvm 20 on 9.12.2

On Wed, Apr 2, 2025 at 9:06 AM George Colpitts <george.colpitts at gmail.com>
wrote:

> Filed https://gitlab.haskell.org/ghc/ghc/-/issues/25915
>
> On Tue, Apr 1, 2025 at 2:11 PM Andreas Klebinger via ghc-devs <
> ghc-devs at haskell.org> wrote:
>
>> 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 <allbery.b at gmail.com>
>> 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 <
>>> george.colpitts at gmail.com> 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
>>>>
>>>> _______________________________________________
>>>> ghc-devs mailing list
>>>> ghc-devs at haskell.org
>>>> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs
>>>>
>>>
>>>
>>> --
>>> brandon s allbery kf8nh
>>> allbery.b at gmail.com
>>>
>>
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