Re: [PATCH 1/3] STABS: remove -gstabs and -gxcoff functionality

[Michael Matz <matz@suse.de>]

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Hello,

On Thu, 10 Nov 2022, Martin Liška wrote:

> > These changes are part of
> > commit r13-2361-g7e0db0cdf01e9c885a29cb37415f5bc00d90c029
> > "STABS: remove -gstabs and -gxcoff functionality".  What this does is
> > remove these identifiers from "poisoning":
> > 
> >      /* As the last action in this file, we poison the identifiers that
> >         shouldn't be used.
> >      [...]
> >      /* Other obsolete target macros, or macros that used to be in target
> >         headers and were not used, and may be obsolete or may never have
> >         been used.  */
> >       #pragma GCC poison [...]
> > 
> > Shouldn't these identifiers actually stay (so that any accidental future
> > use gets flagged, as I understand this machinery), and instead more
> > identifiers be added potentially: those where their definition/use got
> > removed with "STABS: remove -gstabs and -gxcoff functionality"?  (I've
> > not checked.)
> 
> Well, the identifiers are not used any longer, so I don't think we should
> poison them. Or do I miss something?

It's the very nature of poisoned identifiers that they aren't used (every 
use would get flagged as error).  The point of poisoning them is to avoid 
future new uses to creep in (e.g. via mislead back- or forward-ports, 
which can for instance happen easily with backend macros when an 
out-of-tree port is eventually tried to be integrated).  Hence, generally 
the list of those identifiers is only extended, never reduced.  (There may 
be exceptions of course)


Ciao,
Michael.