# Compile it with: crystal build --prelude=empty --emit llvm-ir noprelude_exception.cr

lib LibC
  alias SizeT = UInt64
  fun printf(format : UInt8*, ...) : Int32
  fun exit(exit_code : Int32) : NoReturn
end

require "callstack/lib_unwind"

struct UInt64
  def self.zero
    0
  end
end

class String
  def to_unsafe
    pointerof(@c)
  end
end

fun __crystal_personality(version : Int32, actions : LibUnwind::Action, exception_class : UInt64, exception_object : LibUnwind::Exception*, context : Void*) : LibUnwind::ReasonCode
  return LibUnwind::ReasonCode::CONTINUE_UNWIND
end

@[Raises]
fun __crystal_raise(unwind_ex : LibUnwind::Exception*) : NoReturn
  ret = LibUnwind.raise_exception(unwind_ex)
  LibC.printf "Failed to raise an exception: %d\n".to_unsafe, ret
  #CallStack.print_backtrace
  LibC.exit(ret.value)
end

def raise(str : String) : NoReturn
  unwind_ex = LibUnwind::Exception.new
  unwind_ex.exception_class = LibC::SizeT.zero
  unwind_ex.exception_cleanup = LibC::SizeT.zero
  unwind_ex.exception_object = str.object_id
  unwind_ex.exception_type_id = str.crystal_type_id
  __crystal_raise(pointerof(unwind_ex))
end

begin
  var = 2
  LibC.printf("in begin: var = %d\n", var)
  raise "I'm an exception!"
ensure
  var = 3
  LibC.printf("in ensure: var = %d\n", var)
end

LibC.printf("after: var = %d\n", var)