Re: [PATCH v9 33/41] environment: add set_index_file()

Stefan Beller [off-list ref] writes:

In cache.h we have a NO_THE_INDEX_COMPATIBILITY_MACROS,
and lots of
  #define foo_bar(..) frob_bar(&the_index, (..))

Could you operate on the raw functions that take pointers to &the_index
and point these to a temporary index?

Isn't mention of the_index is a red-herring?

The in-core index_state does not even know what file it needs to be
written to, so whether you explicitly specify your own index or use
the compat macros to access the_index, you would need to specify to
which file you would write it out or from which file you would read
the new contents.