error: fn_abi_of(pass_zst) = FnAbi {
           args: [
               ArgAbi {
                   layout: TyAndLayout {
                       ty: (),
                       layout: Layout {
                           size: Size(0 bytes),
                           align: AbiAndPrefAlign {
                               abi: $SOME_ALIGN,
                               pref: $SOME_ALIGN,
                           },
                           abi: Memory {
                               sized: true,
                           },
                           fields: Arbitrary {
                               offsets: [],
                               memory_index: [],
                           },
                           largest_niche: None,
                           variants: Single {
                               index: 0,
                           },
                           max_repr_align: None,
                           unadjusted_abi_align: $SOME_ALIGN,
                       },
                   },
                   mode: Ignore,
               },
           ],
           ret: ArgAbi {
               layout: TyAndLayout {
                   ty: (),
                   layout: Layout {
                       size: Size(0 bytes),
                       align: AbiAndPrefAlign {
                           abi: $SOME_ALIGN,
                           pref: $SOME_ALIGN,
                       },
                       abi: Memory {
                           sized: true,
                       },
                       fields: Arbitrary {
                           offsets: [],
                           memory_index: [],
                       },
                       largest_niche: None,
                       variants: Single {
                           index: 0,
                       },
                       max_repr_align: None,
                       unadjusted_abi_align: $SOME_ALIGN,
                   },
               },
               mode: Ignore,
           },
           c_variadic: false,
           fixed_count: 1,
           conv: X86_64SysV,
           can_unwind: false,
       }
  --> $DIR/sysv64-zst.rs:8:1
   |
LL | extern "sysv64" fn pass_zst(_: ()) {}
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 1 previous error