Function rustc_mir_transform::ffi_unwind_calls::abi_can_unwind

fn abi_can_unwind(abi: Abi) -> bool

Some of the functions declared as “may unwind” by fn_can_unwind can’t actually unwind. In particular, extern "C" is still considered as can-unwind on stable, but we need to consider it cannot-unwind here. So below we check fn_can_unwind() && abi_can_unwind() before concluding that a function call can unwind.