[PING*3][PATCH 4/6] gdb/progspace: Add reverse safe iterator and template for unwrapping iterator

[Aaron Merey <amerey@redhat.com>]

Ping

Thanks,
Aaron

On Mon, Jul 3, 2023 at 1:39 PM Aaron Merey <amerey@redhat.com> wrote:
>
> Ping
>
> Thanks,
> Aaron
>
> On Thu, Jun 15, 2023 at 9:44 AM Aaron Merey <amerey@redhat.com> wrote:
> >
> > Ping
> >
> > Thanks,
> > Aaron
> >
> > On Wed, May 31, 2023 at 9:44 PM Aaron Merey <amerey@redhat.com> wrote:
> > >
> > > To facilitate the deletion of objfiles, progspace objects use a safe
> > > iterator that holds a reference to the next objfile in the progspace's
> > > objfile_list.  This allows objfiles to be deleted in a loop without
> > > invalidating the loop's iterator.  progspace also uses an unwrapping
> > > iterator over std::unique_ptr<objfile> that automatically deferences
> > > the unique_ptr.
> > >
> > > This patch changes the objfile safe iterator to be a reverse safe
> > > iterator.  It changes the unwrapping iterator into a template.  It
> > > also modifies objfile_list insertion so that separate debug objfiles
> > > are placed into the list after the parent objfile, instead of before.
> > >
> > > These changes are intended to prepare gdb for on-demand debuginfo
> > > downloading and the downloading of .gdb_index sections.
> > >
> > > With on-demand downloading enabled, gdb might download a debuginfo
> > > file during symtab expansion.  In this case an objfile could be added
> > > to an objfiles_list during iteration over the list (for example, in
> > > iterate_over_symtabs).  We want these loops to also iterate over newly
> > > downloaded objfiles. So objfiles need to be inserted into objfiles_list
> > > after their parent since it is during the search of the parent
> > > objfile for some symbol or filename that the separate debug objfile
> > > might be downloaded.
> > >
> > > The unwrapping iterator is changed into a template in order to
> > > use it with objfile qf_require_partial_symbols, which is now also
> > > uses with a safe iterator.  This is because after a separate debug
> > > objfile is downloaded on-demand, we want to remove any .gdb_index
> > > quick_symbol_functions from the parent objfile during iteration over
> > > the parent's quick_symbol_functions.  The newly downloaded separate
> > > debug objfile contains the index and all of the related symbols
> > > so the .gdb_index should not be associated with the parent objfile
> > > any longer.
> > >
> > > Finally a safe reverse iterator is now used during progspace objfile
> > > deletion in order to prevent iterator invalidation during the loop
> > > in which objfiles are deleted.  This could happen during forward
> > > iteration over objfiles_list when a separate debug objfile immediately
> > > follows it's parent objfile in the list (which is now possible since
> > > objfiles are inserted into the list after their parent).  Deletion
> > > of the parent would cause deletion of the separate debug objfile,
> > > which would invalidate the safe forward iterator's reference to the
> > > next objfile in the list.  A safe reverse iterator deletes separate
> > > debug objfiles before their parent, so the iterator's reference to
> > > the next objfile always stays valid.
> > >
> > > A small change was also made to a testcase in py-objfile.exp to
> > > account for the new placement of separate debug objfiles in
> > > objfiles_list.
> > > ---
> > >  gdb/objfiles.h                          |  22 +++-
> > >  gdb/progspace.c                         |   8 +-
> > >  gdb/progspace.h                         | 159 +++++++++++++++++++-----
> > >  gdb/symfile-debug.c                     | 136 ++++++++++----------
> > >  gdb/testsuite/gdb.python/py-objfile.exp |   2 +-
> > >  5 files changed, 218 insertions(+), 109 deletions(-)
> > >
> > > diff --git a/gdb/objfiles.h b/gdb/objfiles.h
> > > index 189856f0a51..bb7b0a4579d 100644
> > > --- a/gdb/objfiles.h
> > > +++ b/gdb/objfiles.h
> > > @@ -613,6 +613,17 @@ struct objfile
> > >    /* See quick_symbol_functions.  */
> > >    void require_partial_symbols (bool verbose);
> > >
> > > +  /* Remove TARGET from this objfile's collection of quick_symbol_functions.  */
> > > +  void remove_partial_symbol (quick_symbol_functions *target)
> > > +  {
> > > +    for (quick_symbol_functions_up &qf_up : qf)
> > > +      if (qf_up.get () == target)
> > > +       {
> > > +         qf.remove (qf_up);
> > > +         return;
> > > +       }
> > > +  }
> > > +
> > >    /* Return the relocation offset applied to SECTION.  */
> > >    CORE_ADDR section_offset (bfd_section *section) const
> > >    {
> > > @@ -699,13 +710,20 @@ struct objfile
> > >
> > >  private:
> > >
> > > +  using qf_list = std::forward_list<quick_symbol_functions_up>;
> > > +  using unwrapping_qf_range = iterator_range<unwrapping_iterator<qf_list::iterator>>;
> > > +  using qf_safe_range = basic_safe_range<unwrapping_qf_range>;
> > > +
> > >    /* Ensure that partial symbols have been read and return the "quick" (aka
> > >       partial) symbol functions for this symbol reader.  */
> > > -  const std::forward_list<quick_symbol_functions_up> &
> > > +  qf_safe_range
> > >    qf_require_partial_symbols ()
> > >    {
> > >      this->require_partial_symbols (true);
> > > -    return qf;
> > > +    return qf_safe_range
> > > +      (unwrapping_qf_range
> > > +       (unwrapping_iterator<qf_list::iterator> (qf.begin ()),
> > > +        unwrapping_iterator<qf_list::iterator> (qf.end ())));
> > >    }
> > >
> > >  public:
> > > diff --git a/gdb/progspace.c b/gdb/progspace.c
> > > index 32bdfebcf7c..1ed75eef2f9 100644
> > > --- a/gdb/progspace.c
> > > +++ b/gdb/progspace.c
> > > @@ -139,19 +139,19 @@ program_space::free_all_objfiles ()
> > >
> > >  void
> > >  program_space::add_objfile (std::unique_ptr<objfile> &&objfile,
> > > -                           struct objfile *before)
> > > +                           struct objfile *after)
> > >  {
> > > -  if (before == nullptr)
> > > +  if (after == nullptr)
> > >      objfiles_list.push_back (std::move (objfile));
> > >    else
> > >      {
> > >        auto iter = std::find_if (objfiles_list.begin (), objfiles_list.end (),
> > >                                 [=] (const std::unique_ptr<::objfile> &objf)
> > >                                 {
> > > -                                 return objf.get () == before;
> > > +                                 return objf.get () == after;
> > >                                 });
> > >        gdb_assert (iter != objfiles_list.end ());
> > > -      objfiles_list.insert (iter, std::move (objfile));
> > > +      objfiles_list.insert (++iter, std::move (objfile));
> > >      }
> > >  }
> > >
> > > diff --git a/gdb/progspace.h b/gdb/progspace.h
> > > index 85215f0e2f1..6e33e48c88e 100644
> > > --- a/gdb/progspace.h
> > > +++ b/gdb/progspace.h
> > > @@ -40,56 +40,141 @@ struct address_space;
> > >  struct program_space;
> > >  struct so_list;
> > >
> > > +/* An iterator that wraps an iterator over std::unique_ptr, and dereferences
> > > +   the returned object.  This is useful for iterating over a list of shared
> > > +   pointers and returning raw pointers -- which helped avoid touching a lot
> > > +   of code when changing how objfiles are managed.  */
> > > +
> > > +template<typename UniquePtrIter>
> > > +class unwrapping_iterator
> > > +{
> > > +public:
> > > +  typedef unwrapping_iterator self_type;
> > > +  typedef typename UniquePtrIter::value_type::pointer value_type;
> > > +  typedef typename UniquePtrIter::reference  reference;
> > > +  typedef typename UniquePtrIter::pointer pointer;
> > > +  typedef typename UniquePtrIter::iterator_category iterator_category;
> > > +  typedef typename UniquePtrIter::difference_type difference_type;
> > > +
> > > +  unwrapping_iterator (UniquePtrIter iter)
> > > +    : m_iter (std::move (iter))
> > > +  {
> > > +  }
> > > +
> > > +  value_type operator* () const
> > > +  {
> > > +    return m_iter->get ();
> > > +  }
> > > +
> > > +  unwrapping_iterator operator++ ()
> > > +  {
> > > +    ++m_iter;
> > > +    return *this;
> > > +  }
> > > +
> > > +  bool operator!= (const unwrapping_iterator &other) const
> > > +  {
> > > +    return m_iter != other.m_iter;
> > > +  }
> > > +
> > > +private:
> > > +  /* The underlying iterator.  */
> > > +  UniquePtrIter m_iter;
> > > +};
> > > +
> > >  typedef std::list<std::unique_ptr<objfile>> objfile_list;
> > >
> > > -/* An iterator that wraps an iterator over std::unique_ptr<objfile>,
> > > -   and dereferences the returned object.  This is useful for iterating
> > > -   over a list of shared pointers and returning raw pointers -- which
> > > -   helped avoid touching a lot of code when changing how objfiles are
> > > -   managed.  */
> > > +/* An reverse iterator that wraps an iterator over objfile_list, and
> > > +   dereferences the returned object.  This is useful for reverse iterating
> > > +   over a list of shared pointers and returning raw pointers -- which helped
> > > +   avoid touching a lot of code when changing how objfiles are managed.  */
> > >
> > > -class unwrapping_objfile_iterator
> > > +class unwrapping_reverse_objfile_iterator
> > >  {
> > >  public:
> > > -
> > > -  typedef unwrapping_objfile_iterator self_type;
> > > +  typedef unwrapping_reverse_objfile_iterator self_type;
> > >    typedef typename ::objfile *value_type;
> > >    typedef typename ::objfile &reference;
> > >    typedef typename ::objfile **pointer;
> > >    typedef typename objfile_list::iterator::iterator_category iterator_category;
> > >    typedef typename objfile_list::iterator::difference_type difference_type;
> > >
> > > -  unwrapping_objfile_iterator (objfile_list::iterator iter)
> > > -    : m_iter (std::move (iter))
> > > -  {
> > > -  }
> > > -
> > > -  objfile *operator* () const
> > > +  value_type operator* () const
> > >    {
> > >      return m_iter->get ();
> > >    }
> > >
> > > -  unwrapping_objfile_iterator operator++ ()
> > > +  unwrapping_reverse_objfile_iterator operator++ ()
> > >    {
> > > -    ++m_iter;
> > > +    if (m_iter != m_begin)
> > > +      --m_iter;
> > > +    else
> > > +      {
> > > +       /* We can't decrement M_ITER since it is the begin iterator of the
> > > +          objfile list.  Set M_ITER to the list's end iterator to indicate
> > > +          this is now one-past-the-end.  */
> > > +       m_iter = m_end;
> > > +
> > > +       /* Overwrite M_BEGIN to avoid possibly copying an invalid iterator.  */
> > > +       m_begin = m_end;
> > > +      }
> > > +
> > >      return *this;
> > >    }
> > >
> > > -  bool operator!= (const unwrapping_objfile_iterator &other) const
> > > +  bool operator!= (const unwrapping_reverse_objfile_iterator &other) const
> > >    {
> > >      return m_iter != other.m_iter;
> > >    }
> > >
> > > +  /* Return an unwrapping reverse iterator starting at the last element of
> > > +     OBJF_LIST.  */
> > > +  static unwrapping_reverse_objfile_iterator begin (objfile_list &objf_list)
> > > +  {
> > > +    auto begin = objf_list.begin ();
> > > +    auto end = objf_list.end ();
> > > +    auto rev_begin = objf_list.end ();
> > > +
> > > +    /* Start REV_BEGIN on the last objfile in OBJF_LIST.  */
> > > +    if (begin != end)
> > > +      --rev_begin;
> > > +
> > > +    return unwrapping_reverse_objfile_iterator (rev_begin, begin, end);
> > > +  }
> > > +
> > > +  /* Return a one-past-the-end unwrapping reverse iterator.  */
> > > +  static unwrapping_reverse_objfile_iterator end (objfile_list &objf_list)
> > > +  {
> > > +    return unwrapping_reverse_objfile_iterator (objf_list.end (),
> > > +                                               objf_list.end (),
> > > +                                               objf_list.end ());
> > > +  }
> > > +
> > >  private:
> > > +  /* begin and end methods should be used to create these objects.  */
> > > +  unwrapping_reverse_objfile_iterator (objfile_list::iterator iter,
> > > +                                      objfile_list::iterator begin,
> > > +                                      objfile_list::iterator end)
> > > +    : m_iter (std::move (iter)), m_begin (std::move (begin)),
> > > +      m_end (std::move (end))
> > > +  {
> > > +  }
> > >
> > > -  /* The underlying iterator.  */
> > > -  objfile_list::iterator m_iter;
> > > -};
> > > + /* The underlying iterator.  */
> > > + objfile_list::iterator m_iter;
> > >
> > > + /* The underlying iterator pointing to the first objfile in the sequence.  Used
> > > +    to track when to stop decrementing M_ITER.  */
> > > + objfile_list::iterator m_begin;
> > >
> > > -/* A range that returns unwrapping_objfile_iterators.  */
> > > +  /* The underlying iterator's one-past-the-end.  */
> > > + objfile_list::iterator m_end;
> > > +};
> > >
> > > -using unwrapping_objfile_range = iterator_range<unwrapping_objfile_iterator>;
> > > +/* A range that returns unwrapping_iterators.  */
> > > +
> > > +using unwrapping_objfile_range
> > > +  = iterator_range<unwrapping_iterator<objfile_list::iterator>>;
> > >
> > >  /* A program space represents a symbolic view of an address space.
> > >     Roughly speaking, it holds all the data associated with a
> > > @@ -209,11 +294,12 @@ struct program_space
> > >    objfiles_range objfiles ()
> > >    {
> > >      return objfiles_range
> > > -      (unwrapping_objfile_iterator (objfiles_list.begin ()),
> > > -       unwrapping_objfile_iterator (objfiles_list.end ()));
> > > +      (unwrapping_iterator<objfile_list::iterator> (objfiles_list.begin ()),
> > > +       unwrapping_iterator<objfile_list::iterator> (objfiles_list.end ()));
> > >    }
> > >
> > > -  using objfiles_safe_range = basic_safe_range<objfiles_range>;
> > > +  using objfiles_reverse_range = iterator_range<unwrapping_reverse_objfile_iterator>;
> > > +  using objfiles_safe_reverse_range = basic_safe_range<objfiles_reverse_range>;
> > >
> > >    /* An iterable object that can be used to iterate over all objfiles.
> > >       The basic use is in a foreach, like:
> > > @@ -221,20 +307,25 @@ struct program_space
> > >       for (objfile *objf : pspace->objfiles_safe ()) { ... }
> > >
> > >       This variant uses a basic_safe_iterator so that objfiles can be
> > > -     deleted during iteration.  */
> > > -  objfiles_safe_range objfiles_safe ()
> > > +     deleted during iteration.
> > > +
> > > +     The use of a reverse iterator helps ensure that separate debug
> > > +     objfiles are deleted before their parent objfile.  This prevents
> > > +     the invalidation of an iterator due to the deletion of a parent
> > > +     objfile.  */
> > > +  objfiles_safe_reverse_range objfiles_safe ()
> > >    {
> > > -    return objfiles_safe_range
> > > -      (objfiles_range
> > > -        (unwrapping_objfile_iterator (objfiles_list.begin ()),
> > > -         unwrapping_objfile_iterator (objfiles_list.end ())));
> > > +    return objfiles_safe_reverse_range
> > > +      (objfiles_reverse_range
> > > +       (unwrapping_reverse_objfile_iterator::begin (objfiles_list),
> > > +        unwrapping_reverse_objfile_iterator::end (objfiles_list)));
> > >    }
> > >
> > > -  /* Add OBJFILE to the list of objfiles, putting it just before
> > > -     BEFORE.  If BEFORE is nullptr, it will go at the end of the
> > > +  /* Add OBJFILE to the list of objfiles, putting it just after
> > > +     AFTER.  If AFTER is nullptr, it will go at the end of the
> > >       list.  */
> > >    void add_objfile (std::unique_ptr<objfile> &&objfile,
> > > -                   struct objfile *before);
> > > +                   struct objfile *after);
> > >
> > >    /* Remove OBJFILE from the list of objfiles.  */
> > >    void remove_objfile (struct objfile *objfile);
> > > diff --git a/gdb/symfile-debug.c b/gdb/symfile-debug.c
> > > index 9db5c47a8ce..784b81b5ca6 100644
> > > --- a/gdb/symfile-debug.c
> > > +++ b/gdb/symfile-debug.c
> > > @@ -109,9 +109,9 @@ objfile::has_unexpanded_symtabs ()
> > >                 objfile_debug_name (this));
> > >
> > >    bool result = false;
> > > -  for (const auto &iter : qf_require_partial_symbols ())
> > > +  for (quick_symbol_functions *qf : qf_require_partial_symbols ())
> > >      {
> > > -      if (iter->has_unexpanded_symtabs (this))
> > > +      if (qf->has_unexpanded_symtabs (this))
> > >         {
> > >           result = true;
> > >           break;
> > > @@ -134,9 +134,9 @@ objfile::find_last_source_symtab ()
> > >      gdb_printf (gdb_stdlog, "qf->find_last_source_symtab (%s)\n",
> > >                 objfile_debug_name (this));
> > >
> > > -  for (const auto &iter : qf_require_partial_symbols ())
> > > +  for (quick_symbol_functions *qf : qf_require_partial_symbols ())
> > >      {
> > > -      retval = iter->find_last_source_symtab (this);
> > > +      retval = qf->find_last_source_symtab (this);
> > >        if (retval != nullptr)
> > >         break;
> > >      }
> > > @@ -167,8 +167,8 @@ objfile::forget_cached_source_info ()
> > >         }
> > >      }
> > >
> > > -  for (const auto &iter : qf_require_partial_symbols ())
> > > -    iter->forget_cached_source_info (this);
> > > +  for (quick_symbol_functions *qf : qf_require_partial_symbols ())
> > > +    qf->forget_cached_source_info (this);
> > >  }
> > >
> > >  bool
> > > @@ -214,17 +214,17 @@ objfile::map_symtabs_matching_filename
> > >      return result;
> > >    };
> > >
> > > -  for (const auto &iter : qf_require_partial_symbols ())
> > > +  for (quick_symbol_functions *qf : qf_require_partial_symbols ())
> > >      {
> > > -      if (!iter->expand_symtabs_matching (this,
> > > -                                         match_one_filename,
> > > -                                         nullptr,
> > > -                                         nullptr,
> > > -                                         on_expansion,
> > > -                                         (SEARCH_GLOBAL_BLOCK
> > > -                                          | SEARCH_STATIC_BLOCK),
> > > -                                         UNDEF_DOMAIN,
> > > -                                         ALL_DOMAIN))
> > > +      if (!qf->expand_symtabs_matching (this,
> > > +                                       match_one_filename,
> > > +                                       nullptr,
> > > +                                       nullptr,
> > > +                                       on_expansion,
> > > +                                       (SEARCH_GLOBAL_BLOCK
> > > +                                        | SEARCH_STATIC_BLOCK),
> > > +                                       UNDEF_DOMAIN,
> > > +                                       ALL_DOMAIN))
> > >         {
> > >           retval = false;
> > >           break;
> > > @@ -283,18 +283,18 @@ objfile::lookup_symbol (block_enum kind, const char *name, domain_enum domain)
> > >      return true;
> > >    };
> > >
> > > -  for (const auto &iter : qf_require_partial_symbols ())
> > > +  for (quick_symbol_functions *qf : qf_require_partial_symbols ())
> > >      {
> > > -      if (!iter->expand_symtabs_matching (this,
> > > -                                         nullptr,
> > > -                                         &lookup_name,
> > > -                                         nullptr,
> > > -                                         search_one_symtab,
> > > -                                         kind == GLOBAL_BLOCK
> > > -                                         ? SEARCH_GLOBAL_BLOCK
> > > -                                         : SEARCH_STATIC_BLOCK,
> > > -                                         domain,
> > > -                                         ALL_DOMAIN))
> > > +      if (!qf->expand_symtabs_matching (this,
> > > +                                       nullptr,
> > > +                                       &lookup_name,
> > > +                                       nullptr,
> > > +                                       search_one_symtab,
> > > +                                       kind == GLOBAL_BLOCK
> > > +                                       ? SEARCH_GLOBAL_BLOCK
> > > +                                       : SEARCH_STATIC_BLOCK,
> > > +                                       domain,
> > > +                                       ALL_DOMAIN))
> > >         break;
> > >      }
> > >
> > > @@ -314,8 +314,8 @@ objfile::print_stats (bool print_bcache)
> > >      gdb_printf (gdb_stdlog, "qf->print_stats (%s, %d)\n",
> > >                 objfile_debug_name (this), print_bcache);
> > >
> > > -  for (const auto &iter : qf_require_partial_symbols ())
> > > -    iter->print_stats (this, print_bcache);
> > > +  for (quick_symbol_functions *qf : qf_require_partial_symbols ())
> > > +    qf->print_stats (this, print_bcache);
> > >  }
> > >
> > >  void
> > > @@ -340,16 +340,16 @@ objfile::expand_symtabs_for_function (const char *func_name)
> > >    lookup_name_info base_lookup (func_name, symbol_name_match_type::FULL);
> > >    lookup_name_info lookup_name = base_lookup.make_ignore_params ();
> > >
> > > -  for (const auto &iter : qf_require_partial_symbols ())
> > > -    iter->expand_symtabs_matching (this,
> > > -                                  nullptr,
> > > -                                  &lookup_name,
> > > -                                  nullptr,
> > > -                                  nullptr,
> > > -                                  (SEARCH_GLOBAL_BLOCK
> > > -                                   | SEARCH_STATIC_BLOCK),
> > > -                                  VAR_DOMAIN,
> > > -                                  ALL_DOMAIN);
> > > +  for (quick_symbol_functions *qf : qf_require_partial_symbols ())
> > > +    qf->expand_symtabs_matching (this,
> > > +                                nullptr,
> > > +                                &lookup_name,
> > > +                                nullptr,
> > > +                                nullptr,
> > > +                                (SEARCH_GLOBAL_BLOCK
> > > +                                 | SEARCH_STATIC_BLOCK),
> > > +                                VAR_DOMAIN,
> > > +                                ALL_DOMAIN);
> > >  }
> > >
> > >  void
> > > @@ -359,8 +359,8 @@ objfile::expand_all_symtabs ()
> > >      gdb_printf (gdb_stdlog, "qf->expand_all_symtabs (%s)\n",
> > >                 objfile_debug_name (this));
> > >
> > > -  for (const auto &iter : qf_require_partial_symbols ())
> > > -    iter->expand_all_symtabs (this);
> > > +  for (quick_symbol_functions *qf : qf_require_partial_symbols ())
> > > +    qf->expand_all_symtabs (this);
> > >  }
> > >
> > >  void
> > > @@ -377,16 +377,16 @@ objfile::expand_symtabs_with_fullname (const char *fullname)
> > >      return filename_cmp (basenames ? basename : fullname, filename) == 0;
> > >    };
> > >
> > > -  for (const auto &iter : qf_require_partial_symbols ())
> > > -    iter->expand_symtabs_matching (this,
> > > -                                  file_matcher,
> > > -                                  nullptr,
> > > -                                  nullptr,
> > > -                                  nullptr,
> > > -                                  (SEARCH_GLOBAL_BLOCK
> > > -                                   | SEARCH_STATIC_BLOCK),
> > > -                                  UNDEF_DOMAIN,
> > > -                                  ALL_DOMAIN);
> > > +  for (quick_symbol_functions *qf : qf_require_partial_symbols ())
> > > +    qf->expand_symtabs_matching (this,
> > > +                                file_matcher,
> > > +                                nullptr,
> > > +                                nullptr,
> > > +                                nullptr,
> > > +                                (SEARCH_GLOBAL_BLOCK
> > > +                                 | SEARCH_STATIC_BLOCK),
> > > +                                UNDEF_DOMAIN,
> > > +                                ALL_DOMAIN);
> > >  }
> > >
> > >  void
> > > @@ -402,9 +402,9 @@ objfile::expand_matching_symbols
> > >                 domain_name (domain), global,
> > >                 host_address_to_string (ordered_compare));
> > >
> > > -  for (const auto &iter : qf_require_partial_symbols ())
> > > -    iter->expand_matching_symbols (this, name, domain, global,
> > > -                                  ordered_compare);
> > > +  for (quick_symbol_functions *qf : qf_require_partial_symbols ())
> > > +    qf->expand_matching_symbols (this, name, domain, global,
> > > +                                ordered_compare);
> > >  }
> > >
> > >  bool
> > > @@ -429,10 +429,10 @@ objfile::expand_symtabs_matching
> > >                 host_address_to_string (&expansion_notify),
> > >                 search_domain_name (kind));
> > >
> > > -  for (const auto &iter : qf_require_partial_symbols ())
> > > -    if (!iter->expand_symtabs_matching (this, file_matcher, lookup_name,
> > > -                                       symbol_matcher, expansion_notify,
> > > -                                       search_flags, domain, kind))
> > > +  for (quick_symbol_functions *qf : qf_require_partial_symbols ())
> > > +    if (!qf->expand_symtabs_matching (this, file_matcher, lookup_name,
> > > +                                     symbol_matcher, expansion_notify,
> > > +                                     search_flags, domain, kind))
> > >        return false;
> > >    return true;
> > >  }
> > > @@ -454,10 +454,10 @@ objfile::find_pc_sect_compunit_symtab (struct bound_minimal_symbol msymbol,
> > >                 host_address_to_string (section),
> > >                 warn_if_readin);
> > >
> > > -  for (const auto &iter : qf_require_partial_symbols ())
> > > +  for (quick_symbol_functions *qf : qf_require_partial_symbols ())
> > >      {
> > > -      retval = iter->find_pc_sect_compunit_symtab (this, msymbol, pc, section,
> > > -                                                  warn_if_readin);
> > > +      retval = qf->find_pc_sect_compunit_symtab (this, msymbol, pc, section,
> > > +                                                warn_if_readin);
> > >        if (retval != nullptr)
> > >         break;
> > >      }
> > > @@ -482,8 +482,8 @@ objfile::map_symbol_filenames (gdb::function_view<symbol_filename_ftype> fun,
> > >                 objfile_debug_name (this),
> > >                 need_fullname);
> > >
> > > -  for (const auto &iter : qf_require_partial_symbols ())
> > > -    iter->map_symbol_filenames (this, fun, need_fullname);
> > > +  for (quick_symbol_functions *qf : qf_require_partial_symbols ())
> > > +    qf->map_symbol_filenames (this, fun, need_fullname);
> > >  }
> > >
> > >  struct compunit_symtab *
> > > @@ -496,9 +496,9 @@ objfile::find_compunit_symtab_by_address (CORE_ADDR address)
> > >                 hex_string (address));
> > >
> > >    struct compunit_symtab *result = NULL;
> > > -  for (const auto &iter : qf_require_partial_symbols ())
> > > +  for (quick_symbol_functions *qf : qf_require_partial_symbols ())
> > >      {
> > > -      result = iter->find_compunit_symtab_by_address (this, address);
> > > +      result = qf->find_compunit_symtab_by_address (this, address);
> > >        if (result != nullptr)
> > >         break;
> > >      }
> > > @@ -521,10 +521,10 @@ objfile::lookup_global_symbol_language (const char *name,
> > >    enum language result = language_unknown;
> > >    *symbol_found_p = false;
> > >
> > > -  for (const auto &iter : qf_require_partial_symbols ())
> > > +  for (quick_symbol_functions *qf : qf_require_partial_symbols ())
> > >      {
> > > -      result = iter->lookup_global_symbol_language (this, name, domain,
> > > -                                                   symbol_found_p);
> > > +      result = qf->lookup_global_symbol_language (this, name, domain,
> > > +                                                 symbol_found_p);
> > >        if (*symbol_found_p)
> > >         break;
> > >      }
> > > diff --git a/gdb/testsuite/gdb.python/py-objfile.exp b/gdb/testsuite/gdb.python/py-objfile.exp
> > > index 61b9942de79..0bf49976b73 100644
> > > --- a/gdb/testsuite/gdb.python/py-objfile.exp
> > > +++ b/gdb/testsuite/gdb.python/py-objfile.exp
> > > @@ -135,7 +135,7 @@ gdb_test "p main" "= {<text variable, no debug info>} $hex <main>" \
> > >  gdb_py_test_silent_cmd "python objfile.add_separate_debug_file(\"${binfile}\")" \
> > >      "Add separate debug file file" 1
> > >
> > > -gdb_py_test_silent_cmd "python sep_objfile = gdb.objfiles()\[0\]" \
> > > +gdb_py_test_silent_cmd "python sep_objfile = gdb.objfiles()\[1\]" \
> > >      "Get separate debug info objfile" 1
> > >
> > >  gdb_test "python print (sep_objfile.owner.filename)" "${testfile}2" \
> > > --
> > > 2.40.1
> > >