Limit diagnostics in floating window to current line

Neovim
1

Is it possible, using the new vim.diagnostic API, to limit the contents of the floating diagnostic window to only diagnostics on the current line?

I tried the config below, but it just shows the default message and the custom function doesn’t seem to be used at all:

  vim.diagnostic.config({
    severity_sort = true,
    virtual_text = {
      severity = { min = vim.diagnostic.severity.WARN },
    },
    float = function(ns, bufnr)
      if bufnr == vim.api.nvim_get_current_buf() then
        local curr_line = vim.fn.line('.')
        return {
          format = function(diagnostic)
            if diagnostic.lnum <= curr_line and diagnostic.end_lnum >= curr_line then
              return ("[%s:%s] (%d:%d - %d:%d) %s"):format(
                diagnostic.source or "?",
                (diagnostic.severity and severity_names[diagnostic.severity]) or "?",
                diagnostic.lnum or "?",
                diagnostic.col or "?",
                diagnostic.end_lnum or "?",
                diagnostic.end_col or "?",
                diagnostic.message
              )
            end
          end
        }
      end
    end,
  })