[PATCH 2/3] gas/ELF: warn upon non-default visibility of local symbols

[Jan Beulich]

On 23.06.2026 03:10, H.J. Lu wrote:
> On Fri, May 8, 2026 at 2:54 PM Jan Beulich <jbeulich@suse.com> wrote:
>>
>> On 10.04.2026 16:17, Jan Beulich wrote:
>>> On 10.04.2026 15:35, Richard Earnshaw (foss) wrote:
>>>> On 10/04/2026 14:31, Jan Beulich wrote:
>>>>> The spec explicitly precludes STB_LOCAL together with STV_PROTECTED (and,
>>>>> implicity, STV_HIDDEN or STV_INTERNAL), so we better wouldn't entirely
>>>>> silently write out symbols violating this.
>>>>>
>>>>> LoongArch's tc_symbol_new_hook() simply needs dropping. If FAKE_LABEL_NAME
>>>>> symbols can end up global, marking them hidden would need doing elsewhere.
>>>>> There not being a need to make any testsuite adjustments suggests though
>>>>> that this won't normally (ever?) happen.
>>>>>
>>>>> A couple of testcases then also need adjustment.
>>>>> ---
>>>>> It would be nice to re-use an existing loop, yet the one in
>>>>> elf_frob_file_before_adjust() comes too early, as does elf_frob_symbol().
>>>>>
>>>>> An alternative may be to imply .global from .hidden etc also for defined
>>>>> symbols (as looks to have been implied by some of the testcases being
>>>>> adjusted). This would then require to reject .local when a visibility was
>>>>> already set.
>>>
>>> As you can see from this, ...
>>>
>>>>> I wonder what purpose STV_* serve with e.g. STT_SECTION. Yet I also wonder
>>>>> what purpose STB_* other than STB_LOCAL serve with STT_SECTION (seeing how
>>>>> bfd/elf.c:swap_out_syms() explicitly uses STB_GLOBAL).
>>>>>
>>>>> The TI C6x testcase adjustments suggest that PLT relocations are
>>>>> needlessly emitted by gas for non-default visibility globals.
>>>>
>>>>
>>>> Do we know that this won't cause issues for real code out in the wild?  Might it not be better to just treat .hidden as making the symbol global, but hidden?
>>>
>>> ... I'm wondering the same. I meant to be conservative (as to exposing new
>>> globals) for v1. If collectively we think changing the behavior that way
>>> makes sense, I'll be happy to try that out for v2.
>>
>> Having thought about this more, implying global from hidden (etc) feels more
>> risky than keeping things as they are in v1: People suddenly may face
>> duplicate symbol linker errors that way. Short of any other comments /
>> opinions, I'll get the series in as is.
> 
> This warning isn't very useful and annoying:
> 
> https://sourceware.org/bugzilla/show_bug.cgi?id=34312

Your judgement feels pretty subjective to me. As said in the bug - people really
should decide: Do they want a local symbol or a hidden one?

Jan