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.