[FFmpeg-devel] duplicate symbol '_dec_init' in: fftools/ffmpeg_dec.o

[Rémi Denis-Courmont]

Le 17 mars 2024 14:13:18 GMT-07:00, Timo Rothenpieler <timo at rothenpieler.org> a écrit :
>On 17.03.2024 18:37, Rémi Denis-Courmont wrote:
>> 
>> 
>> Le 17 mars 2024 10:29:39 GMT-07:00, Andreas Rheinhardt <andreas.rheinhardt at outlook.com> a écrit :
>>> Rémi Denis-Courmont:
>>>> 
>>>> 
>>>> Le 16 mars 2024 13:58:23 GMT-07:00, James Almer <jamrial at gmail.com> a écrit :
>>>>>> Seems the conflict comes from
>>>>>> https://code.videolan.org/videolan/libbluray/-/blob/master/src/libbluray/disc/dec.c?ref_type=heads#L287
>>>>>>    and
>>>>>> https://github.com/FFmpeg/FFmpeg/commit/c4de5778bceab3c15f1239f1f16816749a7fd3b6
>>>>>> 
>>>>>> Perhaps you could also try asking libbluray if they could use an internal
>>>>>> prefix. Otherwise you might need to do a rename of that function on
>>>>>> ffmpeg's side.
>>>>> 
>>>>> libbluray 100% needs to either prefix it, or hid it so it's not exported. It's a library, so it should not be exporting such simple and short unprefix named symbols.
>>>> 
>>>> AFAICT, FFmpeg is just as guilty as Libbluray there. To support static linking, all non-static symbols should be name-spaced, and here both FFmpeg and libbluray are failing, and thus both should be fixed IMO.
>>>> 
>>> 
>>> You forgot that FFmpeg's dec_init is in fftools/the executable, whereas
>>> libbluray's is in the library.
>> 
>> Oh well then it's 100% a problem with FFmpeg, or with the build system used by OP (Possibly a problem with Apple's tools). A static library being imported is not supposed to be able to cause symbol conflicts.
>
>A static library, as opposed to a shared one, has no concept of private symbols.
>The symbol already is not exported by libbr, but in the case of static linking, there is no distinction between exported and hidden symbols.

Yes. But an symbol from an import library is not supposed to conflict with a symbol from the executable (or library) being linked. Hence this looks like a bug in the FFmpeg build system (or whatever OP did with it).

Of course libbr should not leak unprefixed symbols regardless, but that's *not* the root cause.