Build failure: haskell.compiler.ghc{8107,902,92*,94*} on *-darwin

[sternenseemann]

Almost certainly due to the LLVM 16 -> 19 upgrade in #361878. LLVM 18 seems to have added the following check: llvm/llvm-project@d506aa4. It's not yet clear to me how GHC >= 9.6 (with hadrian doesn't trip that issue).

"inplace/bin/ghc-stage1" -optc--target=arm64-apple-darwin -optc-Wall -optc-Wall -optc-Wextra -optc-Wstrict-prototypes -optc-Wmissing-prototypes -optc-Wmissing-declarations -optc-Winline -optc-Wpointer-arith -optc-Wmissing-noreturn -optc-Wnested-externs -optc-Wredundant-decls -optc-Wno-aggregate-return -optc-Wno-unused-label -optc-Iincludes -optc-Iincludes/dist -optc-Iincludes/dist-derivedconstants/header -optc-Iincludes/dist-ghcconstants/header -optc-Iincludes/dist-install/build -optc-Irts -optc-Irts/dist/build -optc-DCOMPILING_RTS -optc-DFS_NAMESPACE=rts -optc-fno-strict-aliasing -optc-fno-common -optc-Irts/dist/build/./autogen -optc-Wno-unknown-pragmas -optc-O2 -optc-fomit-frame-pointer -optc-g -optc-DRtsWay=\"rts_v\" -optc-w -static  -H32m -O -Wall  -Iincludes -Iincludes/dist -Iincludes/dist-derivedconstants/header -Iincludes/dist-ghcconstants/header -Iincludes/dist-install/build -Irts -Irts/dist/build -DCOMPILING_RTS -DFS_NAMESPACE=rts -this-unit-id rts -dcmm-lint     -package-env - -i -irts -irts/dist/build -Irts/dist/build -irts/dist/build/./autogen -Irts/dist/build/./autogen            -O2 -Wcpp-undef   -Wnoncanonical-monad-instances  -c rts/StgCRun.c -o rts/dist/build/StgCRun.o

/private/tmp/nix-build-ghc-9.2.8.drv-0/ghc42576_0/ghc_1.s:54:1: error:
     error: non-private labels cannot appear between .cfi_startproc / .cfi_endproc pairs
   |
54 | _StgReturn:
   | ^
_StgReturn:
^

/private/tmp/nix-build-ghc-9.2.8.drv-0/ghc42576_0/ghc_1.s:12:2: error:
     error: previous .cfi_startproc was here
            .cfi_startproc
            ^
   |
12 |         .cfi_startproc
   |  ^
`cc' failed in phase `Assembler'. (Exit code: 1)
make[1]: *** [rts/ghc.mk:345: rts/dist/build/StgCRun.o] Error 1
make: *** [Makefile:128: all] Error 2

[paparodeo]

.cfi_startproc needs to come after the label not before. we have a number of fixes for this in other packages: eg https://github.com/NixOS/nixpkgs/pull/354734/files tho IIRC fix for ghc is not as simple.

[sternenseemann]

I figured, too, but I have not been able to figure out why GHC >= 9.6 succeeds. It does not look like they've actually reordered anything upstream from diffing the obvious rts source files between 9.4.8 to 9.6.6.

[sternenseemann]

GHC ticket: https://gitlab.haskell.org/ghc/ghc/-/issues/25608

[PedroHLC]

Anyone has a working example of overlay to work around this one? My attempt seem to be nullified somewhere:

Borked attempt

  pkgs = import nixpkgs {
    inherit system;
    config.allowUnfree = true;
    overlays = [
      (final: prev: {
        haskell = prev.haskell // {
          compiler = prev.haskell.compiler // rec {
            ghc928 = prev.haskell.compiler.ghc928.override {
              useLLVM = true;
              llvmPackages = final.llvmPackages_17;
              buildTargetLlvmPackages = final.pkgsBuildTarget.llvmPackages_17;
            };
            ghc92 = ghc928;
          };
        };
      })
    ];
  };

[sternenseemann]

Don't touch useLLVM, llvmPackages nor buildTargetLlvmPackages, they concern GHC's LLVM backend for Haskell code gen. You need to override the stdenv the derivation uses. This may not be enough, though, as GHC also pulls in buildPackages.stdenv.cc which can not be overridden as easily (you'll have to try it, it may not matter during native compilation).