Re: [patchv2] Fix Sun compiler compat. for empty structs (PR build/14003)

[Mark Kettenis <mark.kettenis@xs4all.nl>]

> Date: Wed, 13 Jun 2012 08:50:59 +0200
> From: Jan Kratochvil <jan.kratochvil@redhat.com>
> 
> On Tue, 12 Jun 2012 23:51:16 +0200, Jan Kratochvil wrote:
> > On Tue, 12 Jun 2012 23:24:13 +0200, Joel Brobecker wrote:
> > >         A structure type describes a sequentially allocated nonempty
> > >         set of member objects [...]
> > 
> > oops, OK.
> 
> emptystruct.c:1:8: warning: struct has no members [-pedantic]
> 
> 
> > > Perhaps using #if 0 instead might make it looks like a little less unusual,
> > > not sure...
> > 
> > While #if 0 is IIRC forbidden in general it would at least permit ctags to
> > work.
> 
> 
> Jan
> 
> 
> 2012-06-13  Jan Kratochvil  <jan.kratochvil@redhat.com>
> 
> 	PR build/14003
> 	* inferior.h (struct inferior_suspend_state): Comment out.
> 	(struct inferior): Comment out the field suspend.
> 	* infrun.c (struct infcall_suspend_state): Comment out the field
> 	inferior_suspend.
> 	(save_infcall_suspend_state, restore_infcall_suspend_state): Comment
> 	out its assignment.
> 
> diff --git a/gdb/inferior.h b/gdb/inferior.h
> index dfcbda4..3945962 100644
> --- a/gdb/inferior.h
> +++ b/gdb/inferior.h
> @@ -397,9 +397,11 @@ struct inferior_control_state
>  
>     Inferior thread counterpart is `struct thread_suspend_state'.  */
>  
> +#if 0 /* Currently unused and empty structures are not valid C.  */
>  struct inferior_suspend_state
>  {
>  };
> +#endif

At the risk of turning this into a bikeshed:

Isn't it simpler to just put a dummy member inside that struct, and forget about the #if 0 stuff?

struct inferior_suspend_state
{
	/* Empty structures are not valid C.  */
	int unused;
};

>  /* GDB represents the state of each program execution with an object
>     called an inferior.  An inferior typically corresponds to a process
> @@ -431,7 +433,9 @@ struct inferior
>  
>    /* State of inferior process to restore after GDB is done with an inferior
>       call.  See `struct inferior_suspend_state'.  */
> +#if 0 /* Currently unused and empty structures are not valid C.  */
>    struct inferior_suspend_state suspend;
> +#endif
>  
>    /* True if this was an auto-created inferior, e.g. created from
>       following a fork; false, if this inferior was manually added by
> diff --git a/gdb/infrun.c b/gdb/infrun.c
> index b98e379..e6b7a5e 100644
> --- a/gdb/infrun.c
> +++ b/gdb/infrun.c
> @@ -6639,7 +6639,9 @@ siginfo_make_value (struct gdbarch *gdbarch, struct internalvar *var,
>  struct infcall_suspend_state
>  {
>    struct thread_suspend_state thread_suspend;
> +#if 0 /* Currently unused and empty structures are not valid C.  */
>    struct inferior_suspend_state inferior_suspend;
> +#endif
>  
>    /* Other fields:  */
>    CORE_ADDR stop_pc;
> @@ -6693,7 +6695,9 @@ save_infcall_suspend_state (void)
>      }
>  
>    inf_state->thread_suspend = tp->suspend;
> +#if 0 /* Currently unused and empty structures are not valid C.  */
>    inf_state->inferior_suspend = inf->suspend;
> +#endif
>  
>    /* run_inferior_call will not use the signal due to its `proceed' call with
>       GDB_SIGNAL_0 anyway.  */
> @@ -6717,7 +6721,9 @@ restore_infcall_suspend_state (struct infcall_suspend_state *inf_state)
>    struct gdbarch *gdbarch = get_regcache_arch (regcache);
>  
>    tp->suspend = inf_state->thread_suspend;
> +#if 0 /* Currently unused and empty structures are not valid C.  */
>    inf->suspend = inf_state->inferior_suspend;
> +#endif
>  
>    stop_pc = inf_state->stop_pc;
>  
>