error: proc macro panicked
 --> tests/compile_failures/bad_setting_name_combinebits.rs:5:5
  |
5 |     combinebits!(explode=panic, "aaaa aaaa");
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = help: message: assertion `left == right` failed: Only the 'overflow' setting is supported, but found 'explode'.
            left: "explode"
           right: "overflow"