raise with cause callstack

raise.cr

def raise(ex : Exception) : NoReturn
  if ex.callstack.nil?
    ex.callstack = CallStack.new
  end
  unwind_ex = Pointer(LibUnwind::Exception).malloc
  unwind_ex.value.exception_class = LibC::SizeT.zero
  unwind_ex.value.exception_cleanup = LibC::SizeT.zero
  unwind_ex.value.exception_object = ex.object_id
  unwind_ex.value.exception_type_id = ex.crystal_type_id
  __crystal_raise(unwind_ex)
end

raise_spec.cr

require "spec"

private class SomeError < Exception
  def initialize(cause)
    super("Some error", cause)
  end
end

describe "raise" do
  ex = Exception.new "whatever"
  callstack = CallStack.new
  ex.callstack = callstack

  it "should raise ex with callstack" do
    expect_raises Exception, ex.backtrace do
      raise ex
    end
  end

  it "should raise SomeError with ex cause" do
    expect_raises SomeError, ex.backtrace do
      raise SomeError.new(ex)
    end
  end
end