haskellPackages.llvm-ffi: always use default LLVM version

[wolfgangwalther]

The previous approach of selecting the highest possible LLVM version brought complications, especially when the latest LLVM release candidate was properly released and the llvm-ffi version on master didn't support this, yet. This would result in an eval failure that was impossible to properly solve on master.

We only introduced the logic of selecting the latest LLVM version, because we didn't know about the cabal flags supporting lower LLVM versions at first. We then stuck with this approach. However, we can also just always use the default LLVM version that is present in llvmPackages. This is more in the spirit of a default version anyway.

This will not result in any eval failures / warnings. There is only one failure mode: haskellPackages.llvm-ffi not supporting the new default LLVM version. In this case it's perfectly fine to wait for an update of llvm-ffi via haskell-updates.

Targeting master to unblock #437137 properly, hopefully without creating merge conflicts.

Things done

• Built on platform:
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Ran nixpkgs-review on this PR. See nixpkgs-review usage.
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other READMEs.

---

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[wolfgangwalther]

nixpkgs-review result

Generated using nixpkgs-review.

Command: nixpkgs-review pr 439264
Commit: c4a5576f7bdd10916321d8d580881368f7fe9f85

---

x86_64-linux

✅ 3 packages built:

• haskellPackages.llvm-ffi
• haskellPackages.llvm-ffi.doc
• haskellPackages.llvm-tf

---

aarch64-linux

✅ 3 packages built:

• haskellPackages.llvm-ffi
• haskellPackages.llvm-ffi.doc
• haskellPackages.llvm-tf

---

x86_64-darwin

❌ 1 package failed to build:

• haskellPackages.llvm-tf

✅ 2 packages built:

• haskellPackages.llvm-ffi
• haskellPackages.llvm-ffi.doc

---

aarch64-darwin

❌ 1 package failed to build:

• haskellPackages.llvm-tf

✅ 2 packages built:

• haskellPackages.llvm-ffi
• haskellPackages.llvm-ffi.doc

---

Error logs: `x86_64-darwin`

haskellPackages.llvm-tf

    To import instances alone, use: import Control.Applicative()
   |
49 | import Control.Applicative (liftA2, pure, (<$>))
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
private/LLVM/ExecutionEngine/Marshal.hs:56:50: warning: [GHC-38856] [-Wunused-imports]

The import of ‘Word’ from module ‘Data.Word’ is redundant

|

56 | import Data.Word (Word8, Word16, Word32, Word64, Word)

|                                                  ^^^^
private/LLVM/ExecutionEngine/Marshal.hs:222:54: warning: [GHC-62161] [-Wincomplete-uni-patterns]

Pattern match(es) are non-exhaustive

In a lambda abstraction: Patterns of type ‘[a]’ not matched: []

|

222 |     MS.evalState $ Trav.sequence $ pure $ MS.state $ (y:ys) -> (y,ys)

|                                                      ^^^^^^^^^^^^^^^^^

ld: framework not found vecLib

clang: error: linker command failed with exit code 1 (use -v to see invocation)

cc' failed in phase Linker'. (Exit code: 1)

---

Error logs: `aarch64-darwin`

haskellPackages.llvm-tf

    To import instances alone, use: import Control.Applicative()
   |
49 | import Control.Applicative (liftA2, pure, (<$>))
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
private/LLVM/ExecutionEngine/Marshal.hs:56:50: warning: [GHC-38856] [-Wunused-imports]

The import of ‘Word’ from module ‘Data.Word’ is redundant

|

56 | import Data.Word (Word8, Word16, Word32, Word64, Word)

|                                                  ^^^^
private/LLVM/ExecutionEngine/Marshal.hs:222:54: warning: [GHC-62161] [-Wincomplete-uni-patterns]

Pattern match(es) are non-exhaustive

In a lambda abstraction: Patterns of type ‘[a]’ not matched: []

|

222 |     MS.evalState $ Trav.sequence $ pure $ MS.state $ (y:ys) -> (y,ys)

|                                                      ^^^^^^^^^^^^^^^^^

ld: framework not found vecLib

clang: error: linker command failed with exit code 1 (use -v to see invocation)

cc' failed in phase Linker'. (Exit code: 1)

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haskellPackages.llvm-tf seems to be already broken on master for darwin, so that's not a regression.

[emilazy]

Makes me happy, thank you!