Merge pull request #180964 from amjoseph-nixpkgs/pr/mkSkeletonFromList/simplify

      else if (elemAt l 1) == "elf"

        then { cpu = elemAt l 0; vendor = "unknown";  kernel = "none";     abi = elemAt l 1; }

      else   { cpu = elemAt l 0;                      kernel = elemAt l 1;                   };

    "3" = # Awkward hacks, beware!

      if elemAt l 1 == "apple"

        then { cpu = elemAt l 0; vendor = "apple";    kernel = elemAt l 2;                   }

      else if (elemAt l 1 == "linux") || (elemAt l 2 == "gnu")

        then { cpu = elemAt l 0;                      kernel = elemAt l 1; abi = elemAt l 2; }

      else if (elemAt l 2 == "mingw32") # autotools breaks on -gnu for window

        then { cpu = elemAt l 0; vendor = elemAt l 1; kernel = "windows";                    }

      else if (elemAt l 2 == "wasi")

        then { cpu = elemAt l 0; vendor = elemAt l 1; kernel = "wasi";                       }

      else if (elemAt l 2 == "redox")

        then { cpu = elemAt l 0; vendor = elemAt l 1; kernel = "redox";                      }

      else if (elemAt l 2 == "mmixware")

        then { cpu = elemAt l 0; vendor = elemAt l 1; kernel = "mmixware";                   }

      else if hasPrefix "freebsd" (elemAt l 2)

        then { cpu = elemAt l 0; vendor = elemAt l 1;    kernel = elemAt l 2;                }

      else if hasPrefix "netbsd" (elemAt l 2)

        then { cpu = elemAt l 0; vendor = elemAt l 1;    kernel = elemAt l 2;                }

      else if (elem (elemAt l 2) ["eabi" "eabihf" "elf"])

        then { cpu = elemAt l 0; vendor = "unknown"; kernel = elemAt l 1; abi = elemAt l 2; }

      else if (elemAt l 2 == "ghcjs")

        then { cpu = elemAt l 0; vendor = "unknown"; kernel = elemAt l 2; }

      else if hasPrefix "genode" (elemAt l 2)

        then { cpu = elemAt l 0; vendor = elemAt l 1; kernel = elemAt l 2; }

    "3" =

      # cpu-kernel-environment

      if elemAt l 1 == "linux" ||

         elem (elemAt l 2) ["eabi" "eabihf" "elf" "gnu"]

      then {

        cpu    = elemAt l 0;

        kernel = elemAt l 1;

        abi    = elemAt l 2;

        vendor = "unknown";

      }

      # cpu-vendor-os

      else if elemAt l 1 == "apple" ||

              elem (elemAt l 2) [ "wasi" "redox" "mmixware" "ghcjs" "mingw32" ] ||

              hasPrefix "freebsd" (elemAt l 2) ||

              hasPrefix "netbsd" (elemAt l 2) ||

              hasPrefix "genode" (elemAt l 2)

      then {

        cpu    = elemAt l 0;

        vendor = elemAt l 1;

        kernel = if elemAt l 2 == "mingw32"

                 then "windows"  # autotools breaks on -gnu for window

                 else elemAt l 2;

      }

      else throw "Target specification with 3 components is ambiguous";

    "4" =    { cpu = elemAt l 0; vendor = elemAt l 1; kernel = elemAt l 2; abi = elemAt l 3; };

  }.${toString (length l)}