Re: RFA: Add a check_pch_target_flags target hook

[Richard Sandiford <rsandifo at redhat dot com>]

Geoffrey Keating <geoffk@geoffk.org> writes:
> I presume that the end-point is going to be that you can just annotate
> an option with 'unsafe for PCH' and have it checked.  I like that
> idea.  (I would suggest that you look at how the checking for -g
> works, it's not quite as simple as '-g must match', but maybe that
> kind of thing can just be a special case.)

The idea is certainly to allow that kind of annotation, yes.  Just to
be clear: I'm not making any promises that I'll implement it myself,
but the infrastructure will be there for anyone else who wants to.
It should just be a case of checking a new CL_* flag in
option_affects_pch_p.

The nearer target is to make .opt files perform the same PCH validity
checks as the old TARGET_SWITCHES and TARGET_OPTIONS code.  The next
(and hopefully) final step is to add state variables to target options
that don't otherwise have them.

Richard