Re: [PATCH] [gdb/build] Workaround gcc PR113599

[Sam James <sam@gentoo.org>]

Tom de Vries <tdevries@suse.de> writes:

> Since gcc commit d3f48f68227 ("c++: non-dependent .* operand folding
> [PR112427]"), with gdb we run into PR gcc/113599 [1], a wrong-code bug, as
> reported in PR build/31281.
>
> Work around this by flipping inherit order:
> ...
> -class thread_info : public refcounted_object,
> -		    public intrusive_list_node<thread_info>
> +class thread_info : public intrusive_list_node<thread_info>,
> +		    public refcounted_object
> ...
>
> An argument could be made that this isn't necessary, because this occurred in
> an unreleased gcc version.
>
> However, I think it could be useful when bisecting gcc for other problems in
> building gdb.  Having this workaround means the bisect won't reintroduce the
> problem.  Furthermore, the workaround is harmless.
>
> Tested on Fedora rawhide x86_64.
>
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31281
>
> [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113599
> ---
>  gdb/gdbthread.h | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/gdb/gdbthread.h b/gdb/gdbthread.h
> index e7035d40ad4..1d9730fd1fa 100644
> --- a/gdb/gdbthread.h
> +++ b/gdb/gdbthread.h
> @@ -244,10 +244,11 @@ using private_thread_info_up = std::unique_ptr<private_thread_info>;
>     strong reference, and is thus not accounted for in the thread's
>     refcount.
>  
> -   The intrusive_list_node base links threads in a per-inferior list.  */
> +   The intrusive_list_node base links threads in a per-inferior list.
> +   We place it first in the inherit orer to work around PR gcc/113599.  */

order

>  
> -class thread_info : public refcounted_object,
> -		    public intrusive_list_node<thread_info>
> +class thread_info : public intrusive_list_node<thread_info>,
> +		    public refcounted_object
>  {
>  public:
>    explicit thread_info (inferior *inf, ptid_t ptid);
>
> base-commit: 726f209eb1b05842d816eac8b0b8f9c7f6cd9fbc