Tamar Christina <[email protected]> writes:
>> -----Original Message-----
>> From: Kyrylo Tkachov <[email protected]>
>> Sent: Friday, January 17, 2025 1:22 PM
>> To: Tamar Christina <[email protected]>
>> Cc: GCC Patches <[email protected]>; nd <[email protected]>; Richard
>> Earnshaw <[email protected]>; [email protected]; Richard
>> Sandiford <[email protected]>
>> Subject: Re: [PATCH]AArch64: Drop ILP32 from default elf multilibs after
>> deprecation
>> 
>> 
>> 
>> > On 17 Jan 2025, at 14:06, Tamar Christina <[email protected]> wrote:
>> >
>> >> -----Original Message-----
>> >> From: Kyrylo Tkachov <[email protected]>
>> >> Sent: Friday, January 17, 2025 1:04 PM
>> >> To: Tamar Christina <[email protected]>
>> >> Cc: GCC Patches <[email protected]>; nd <[email protected]>; Richard
>> >> Earnshaw <[email protected]>; [email protected]; Richard
>> >> Sandiford <[email protected]>
>> >> Subject: Re: [PATCH]AArch64: Drop ILP32 from default elf multilibs after
>> >> deprecation
>> >>
>> >>
>> >>
>> >>> On 17 Jan 2025, at 13:56, Tamar Christina <[email protected]> 
>> >>> wrote:
>> >>>
>> >>> Hi All,
>> >>>
>> >>> Following the deprecation of ILP32 *-elf builds fail now due to -Werror 
>> >>> on the
>> >>> deprecation warning.  This is because on embedded builds ILP32 is part 
>> >>> of the
>> >>> default multilib.
>> >>>
>> >>> This patch removed it from the default target as the build would fail 
>> >>> anyway.
>> >>>
>> >>> Cross compiled on aarch64-none-elf and build succeeds now.
>> >>>
>> >>> Ok for master?
>> >>
>> >> I was going to say that it’s more common to just announce deprecation in 
>> >> the
>> >> documentation/release notes for one release cycle, to give time for 
>> >> potential
>> users
>> >> to come forward.
>> >> If we remove the multilib build now we’d be helping the support bitrot 
>> >> much
>> >> faster, which would make it harder to restore if such a user does come 
>> >> forward.
>> >>
>> >
>> > The alternative approach would be to suppress the warning during build, the
>> downside
>> > is ofcourse that this warning does not have a unique identifier, so I 
>> > believe we'd
>> have to
>> > suppress all deprecation warnings:
>> >
>> > cc1: error: '-mabi=ilp32' is deprecated [-Werror=deprecated]
>> >
>> > But could work..
>> >
>> 
>> I think if the warning suppression only happened for the ILP32 multilib 
>> build that
>> would be okay.
>> Other deprecation warnings would be caught in the LP64 build
>
> I can make that work by conditionally changing MULTILIB_OPTIONS in
> gcc/config/aarch64/t-aarch64 when it's collecting the options for ILP32.
>
> What do others think?

To be honest, it seems like a waste of effort to me.  If anyone complains
about the removal of the multilib in GCC 15, we can always revert it for
later releases in the GCC 15 series.  A reversion like that would
presumably also mean reverting the deprecation, since it wouldn't be
worth reinstating the multilib for one release series only.

Thanks,
Richard

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