Compilation warning about unused variable

[DavisVaughan]

In file included from vroom_fwf.cc:7:
./columns.h:125:10: warning: variable 'to_parse' set but not used [-Wunused-but-set-variable]
  size_t to_parse = 0;

https://github.com/tidyverse/vroom/blob/89b6aac8c9c07981a52c28251578deca11810ebd/src/columns.h#L125C10-L131

Looks real? i.e. to_parse doesn't actually get used beyond this loop