Cabal and llvm issue

#1

I am using MacBook and I have installed LLVM@13 using brew install. I have changed .zshrc file also.
export PATH=/opt/homebrew/opt/llvm/bin:/opt/homebrew/bin:$PATH
export LDFLAGS="-L/opt/homebrew/opt/llvm/lib"
export CPPFLAGS="-I/opt/homebrew/opt/llvm/include"

I still get the following error when I run cabal build. Am I still missing something.
: error:
Warning: Couldn’t figure out LLVM version!
Make sure you have installed LLVM between [9 and 13)
ghc: could not execute: opt

#2

Can you run opt --version manually in the terminal?

#3

I get the following
Homebrew LLVM version 13.0.0

#4

The error message says >= 9 && < 13. Not the round parentheses on the right.

#5

Does homebrew really inject their name in there? :man_facepalming: Maybe that’s tripping ghc up as well. The version warning is usually not a hard failure.

#6

I can compile Haskell programs with GHC 8.10.7 and Homebrew LLVM 13.0 on my MacBook Pro 2018 without errors or warnings.

#7

GHC is working fine, it is the issue with cabal. When I try to build with cabal, i get this error.

#8

Compiling with cabal and llvm also works for me. Specifically, creating a new project, adding ghc-options: -fllvm and then running cabal build works for me.

#9

Thank you. ghc-options: -fllvm worked.
I just added this a part of common shared-properties stanza

#10

Interesting… I didn’t know that it is possible to get that error if you did not use -fllvm, I thought that was a requirement for using LLVM with GHC.

#11

For real?? So much for computers adapting to humans so that we didn’t have to adapt to them… I thought it was a typo of some sort.

Anyway, thanks for translating this. Now I’ve learned that Haskell tools will do something like this to me next time I see an error, and hopefully solve my problem sooner

#12

That is actually fairly common mathematical notation. But I agree it’s not that common outside of maths :frowning:

It should be fairly easy to make a patch to ghc to improve the readability. If someone is interested in this, I’m happy to assist.

#13

GHC will default to -fllvm if there is no native code Gen for the target. (AArch64-darwin) only had a NCG from 9.2 onwards. 8.10 will be -fllvm by default.

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#14

Thanks.

In case it helps others, adding ghc-options: -fllvm to my haskell.cabal did help with my initial issue running cabal v2-run, but did not help with calls such as cabal install ...

To fix that I had to use brew install llvm@12 rather than brew install llvm and update the $PATH as suggested.

Hopefully llvm version 13.x will be supported in the future

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