[PATCH 4/8] BFD: Add BFD pointer member to `struct carsym'

[Maciej W. Rozycki]

On Fri, 17 Oct 2025, Jan Beulich wrote:

> > Replace the file offset with a union of one and a BFD pointer in `struct 
> > carsym', as a preparation to handle symbol maps built on the fly rather 
> > than fetched from a file.  No functional change.
> > 
> > NB there's a note on `struct carsym' being a type pun on `struct symdef' 
> > as in include/aout/ranlib.h (or `struct ranlib'; no idea where it comes 
> > from).  With this code update in place it is possibly not true anymore, 
> > depending on the underlying type of `file_ptr'.  This is not a problem 
> > however, because we always process `struct carsym' data by hand and only 
> > use it internally rather than reading/writing from/to a file.  Therefore 
> > only remove the note, as no longer applicable.
> 
> It wasn't quite true already before, as file_ptr != unsigned long (in the
> general case).

 Yeah, also depending on the pointer size, owing to the `s.name' member of 
`struct symdef'.  I guess I'll reword this as follows:

"
NB there's a note on `struct carsym' being a type pun on `struct symdef' 
as in include/aout/ranlib.h (or `struct ranlib'; no idea where it comes 
from).  It is possibly not true anymore, even more so with this code 
update in place, depending on the underlying type of `file_ptr'.  This 
is not a problem however, because we always process `struct carsym' data 
by hand and only use it internally rather than reading/writing from/to a 
file.  Therefore remove the note, as no longer applicable.
"

> > --- binutils-gdb.orig/bfd/archive.c
> > +++ binutils-gdb/bfd/archive.c
> > @@ -149,12 +149,19 @@ extern int errno;
> >  
> >  /*
> >  EXTERNAL
> > +.{* Holds a file position or bfd* depending on context.  *}
> > +.typedef union file_ptr_or_bfd
> > +.{
> > +.  file_ptr file_offset;
> > +.  bfd *abfd;
> > +.}
> > +.file_ptr_or_bfd;
> 
> The comment is too little for my taste, I'm afraid. How would one know which
> of the two it is, merely seeing an instance of this type?

 It's up to the user of this data structure to decide, just as the comment 
says.  Can you please elaborate what kind of description you'd like to see 
here?

 FWIW an equivalent member of `struct orl' gone with 3/8 had yet a terser 
description to the same effect and similarly there was no indication as to 
which union member was to be used when.

  Maciej