Re: [PATCH v2] fbsd-nat: Pacify gcc with no functional changes

[John Baldwin <jhb@FreeBSD.org>]

On 9/11/23 3:40 PM, Enze Li wrote:
> I see these errors on FreeBSD/aarch64 when using gcc 12 without passing
> --disable-werror.
> 
> =====================================================================
>    CXX    fbsd-nat.o
> fbsd-nat.c: In member function 'void fbsd_nat_target::resume_one_process(ptid_t, int, gdb_signal)':
> fbsd-nat.c:1208:11: error: unused variable 'request' [-Werror=unused-variable]
>   1208 |       int request;
>        |           ^~~~~~~
> fbsd-nat.c: In member function 'virtual ptid_t fbsd_nat_target::wait(ptid_t, target_waitstatus*, target_wait_flags)':
> fbsd-nat.c:1726:22: error: declaration of 'inf' shadows a previous local [-Werror=shadow=compatible-local]
>   1726 |       for (inferior *inf : all_non_exited_inferiors (this))
>        |                      ^~~
> fbsd-nat.c:1697:17: note: shadowed declaration is here
>   1697 |       inferior *inf = find_inferior_ptid (this, wptid);
>        |                 ^~~
> fbsd-nat.c: In member function 'virtual void fbsd_nat_target::detach(inferior*, int)':
> fbsd-nat.c:2044:18: error: variable 'wptid' set but not used [-Werror=unused-but-set-variable]
>   2044 |           ptid_t wptid = wait_1 (ptid, &ws, 0);
>        |                  ^~~~~
> cc1plus: all warnings being treated as errors
> =====================================================================
> 
> This patch includes the following non-functional changes,
> 
> 1. Remove unused variable "request".
> 2. Rename inf to inf_p to avoid shadowed declaration warnings.
> 3. Set wptid to null_ptid when USE_SIGTRAP_SIGINFO is defined.

Ah, I had misread the code at first and yes, the variable is unused
when this is defined.

> Tested on FreeBSD/aarch64 by rebuilding.
> ---
>   gdb/fbsd-nat.c | 11 ++++++-----
>   1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/gdb/fbsd-nat.c b/gdb/fbsd-nat.c
> index 0ee3bccb5ef..81a77b3a60f 100644
> --- a/gdb/fbsd-nat.c
> +++ b/gdb/fbsd-nat.c
> @@ -1205,8 +1205,6 @@ fbsd_nat_target::resume_one_process (ptid_t ptid, int step,
>   
>     for (thread_info *tp : inf->non_exited_threads ())
>       {
> -      int request;
> -
>         /* If ptid is a specific LWP, suspend all other LWPs in the
>   	 process, otherwise resume all LWPs in the process..  */
>         if (!ptid.lwp_p() || tp->ptid.lwp () == ptid.lwp ())
> @@ -1694,9 +1692,9 @@ fbsd_nat_target::wait (ptid_t ptid, struct target_waitstatus *ourstatus,
>   	  || ourstatus->kind () == TARGET_WAITKIND_NO_RESUMED)
>   	break;
>   
> -      inferior *inf = find_inferior_ptid (this, wptid);
> -      gdb_assert (inf != nullptr);
> -      fbsd_inferior *fbsd_inf = get_fbsd_inferior (inf);
> +      inferior *winf = find_inferior_ptid (this, wptid);
> +      gdb_assert (winf != nullptr);
> +      fbsd_inferior *fbsd_inf = get_fbsd_inferior (winf);
>         gdb_assert (fbsd_inf != nullptr);
>         gdb_assert (fbsd_inf->resumed_lwps != null_ptid);
>         gdb_assert (fbsd_inf->running_lwps > 0);
> @@ -2094,6 +2092,9 @@ fbsd_nat_target::detach (inferior *inf, int from_tty)
>   			  }
>   		      }
>   		  }
> +#else
> +		  /* pacify gcc  */
> +		  wptid = (void) null_ptid;
>   #endif

Hmm, what I meant was:

	(void) wptid;

This is a way to tell the compiler that the variable should be considered
"used".  I was able to reproduce the warnings on FreeBSD/amd64 as well using
GCC 12 and verified that your patch (with the above fix) fixes the warnings
for me as well, thanks.  I've pushed it.

-- 
John Baldwin