Re: [PATCH] [gdb] Use using instead of typedef

[Tom de Vries <tdevries@suse.de>]

On 6/12/26 1:00 PM, Lancelot SIX wrote:
> On Thu, Jun 11, 2026 at 08:57:48AM +0200, Tom de Vries wrote:
>> On 6/10/26 5:50 PM, Andrew Burgess wrote:
>>> Tom Tromey <tom@tromey.com> writes:
>>>
>>>>>>>>> "Tom" == Tom de Vries <tdevries@suse.de> writes:
>>>>
>>>> Tom> After commit 1eed06ae51d ("[gdbsupport] Use using instead of typedef in
>>>> Tom> next_iterator") I wondered if I could do something similar using sed.
>>>>
>>>> First of all, thanks for doing this.
>>>>
>>>> I don't know how anyone else feels but I normally find 'using' simpler
>>>> to understand, I suppose because I don't need to try to decode the right
>>>> hand side to find the name being defined -- it's right there before the
>>>> '='.
>>>>
>>>> So, I am in favor of this patch.  I'm going to approve it but I think
>>>> you should wait for a bit before checking it in, in case someone wants
>>>> to object.
>>>
>>> I also think this is a good idea.
>>>
>>> +1
>>>
>>
>> Thanks all for the upvotes.  I've pushed this.
>>
>> Thanks,
>> - Toma
> 
> Hi Tom, FYI when building with clang on ubuntu (clang 18.1.3), I see the
> following failure:
> 
>      ../../gdb/nat/amd64-linux-siginfo.c:610:16: error: static assertion failed due to requirement 'sizeof(compat_x32_siginfo_t) == 128'
>        610 | static_assert (sizeof (compat_x32_siginfo_t) == GDB_SI_SIZE);
>            |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>      ../../gdb/nat/amd64-linux-siginfo.c:610:46: note: expression evaluates to '136 == 128'
>        610 | static_assert (sizeof (compat_x32_siginfo_t) == GDB_SI_SIZE);
>            |                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
> 
> I traced this back to this part of your patch:
> 
>      --- a/gdb/nat/amd64-linux-siginfo.c
>      +++ b/gdb/nat/amd64-linux-siginfo.c
>      @@ -203,7 +203,7 @@ struct compat_siginfo_t
>       };
>       
>       /* For x32, clock_t in _sigchld is 64bit aligned at 4 bytes.  */
>      -typedef long __attribute__ ((__aligned__ (4))) compat_x32_clock_t;
>      +using compat_x32_clock_t = long __attribute__ ((__aligned__ (4)));
>       
>       struct __attribute__ ((__aligned__ (8))) compat_x32_siginfo_t
>       {
> 
> I do not think this part is wrong, it seems that clang miss-behaves and
> drops the attribute.
> 
> Should we keep typedef just for this case just to keep compatibility
> with other compilers?
> 

Hi Lancelot,

I've just pushed a patch, please let me know if the problem is not fixed 
for you.

Thanks,
- Tom

> Best,
> Lancelot.
> 
>>
>>
>>> Thanks,
>>> Andrew
>>>
>>