[gold] issues with the lifetime of the archive passed to gold::Incremental_inputs::report_archive

[Rafael Espindola]

I am working on adding the missing archive information for incremental
linking. One issue I just noticed is that an archive passed to
gold::Incremental_inputs::report_archive is deleted in
gold::Add_archive_symbols::run before we get to
gold::Incremental_inputs::sized_create_inputs_section_data.

I can see three ways to try to solve this, but I am not familiar
enough with gold to know the best one:

*) Copy the archive in gold::Incremental_inputs::report_archive.
Simple to do, higher memory use.
*) Extend the lifetime of the archive. Doesn't look so easy, but could
save us some memory.
*) Do work on Incremental_inputs::report_*:

We could create a class (extend  Incremental_inputs itself?) for
incremental link information before opening the input files and update
it as Incremental_inputs::report_* is called. Doing it this way
gold::Incremental_inputs::sized_create_inputs_section_data would be a
simpler method that just serializes the information.

The third option is probably the most efficient. Is it the best one?
Do you foresee any issues in trying to implement it?

Cheers,
-- 
Rafael Ávila de Espíndola