[vlc-devel] [RFC] fix multiple definition of `inet_pton' when including microdns.h on WIN32

[Roland Bewick]

On Mon, 22 Jul 2019 at 12:17 PM, Steve Lhomme <robux4 at ycbcr.xyz> wrote:

> On 2019-07-20 4:53, Roland Bewick wrote:
> >
> > On 19/07/2019 5:50 PM, Steve Lhomme wrote:
> >> On 2019-07-19 12:37, Roland Bewick wrote:
> >>>
> >>> On 19/07/2019 5:12 PM, Steve Lhomme wrote:
> >>>> On 2019-07-19 12:07, Roland Bewick wrote:
> >>>>> Hi Steve, thanks for your reply.
> >>>>>
> >>>>> On 19/07/2019 2:53 PM, Steve Lhomme wrote:
> >>>>>> Hi,
> >>>>>>
> >>>>>> On 2019-07-19 6:04, Roland Bewick wrote:
> >>>>>>>
> >>>>>>> Hi, I'm looking to use the inet_pton function within
> >>>>>>> modules\services_discovery\microdns.c
> >>>>>>>
> >>>>>>> Unfortunately it looks to be defined twice when I cross compile
> >>>>>>> for Windows:
> >>>>>>>
> >>>>>>> 1. in libmicrodns (compat/inet.c) - will only be declared if
> >>>>>>> defined (_WIN32) && !defined(HAVE_INET_NTOP)
> >>>>>>
> >>>>>> On my win32 cross compilation (clang + mingw32) HAVE_INET_NTOP is
> >>>>>> set to 1 so this code is never compiled.
> >>>>>>
> >>>>>>> 2. in libws2_32.a (I think from including winsock2.h?)
> >>>>>>>
> >>>>>>>
> /opt/gcc-x86_64-w64-mingw32/x86_64-w64-mingw32/lib/libws2_32.a(dywbs00169.o):(.text+0x0):
>
> >>>>>>> multiple definition of `inet_pton'
> >>>>>>>
> /win64/vlc/contrib/x86_64-w64-mingw32/lib/libmicrodns.a(inet.o):/win64/libmicrodns/build/../compat/inet.c:60:
>
> >>>>>>> first defined here
> >>>>>>
> >>>>>> When building VLC with the same configuration HAVE_INET_PTON is
> >>>>>> set and thus the compat function is never built either. The ws2_32
> >>>>>> one is used.
> >>>>>>
> >>>>>> So it seems rather an issue in your toolchain/build script. Are
> >>>>>> you using MSVC ? The 3.0 branch ?
> >>>>>
> >>>>>
> >>>>> I followed this docker guide:
> >>>>>
> >>>>> https://gitlab.com/garfvl/daalenv/blob/master/doc/vlc.md for win64
> >>>>> with prebuilt contribs (tip #2 in the readme).
> >>>>>
> >>>>> I’m not using MSVC.
> >>>>>
> >>>>> I’m on the master branch.
> >>>>>
> >>>>> Since I'm using the prebuilt libs and standard? build script for
> >>>>> win64, I'm worried other people might encounter this as well.
> >>>>
> >>>> Maybe the docker uses an outdated version on mingw32 ? It seems very
> >>>> odd that `inet_pton` is defined in ws2_32 but not found in the
> headers.
> >>>>
> >>>> Can you check your config.log to see what it says when checking for
> >>>> it ?
> >>>
> >>> It looks like it's failing so HAVE_INET_PTON is not being set as
> >>> expected.
> >>>
> >>>  From line 13814:
> >>>
> >>> configure:25828: checking for library containing inet_pton
> >>> configure:25859: x86_64-w64-mingw32-gcc -o conftest.exe -g -O2
> >>> -I/win64/vlc/contrib/x86_64-w64-mingw32/include -mms-bitfields
> >>> -I/win64/vlc/contrib/x86_64-w64-mingw32/include
> >>> -D__USE_MINGW_ANSI_STDIO=1  -Wl,--nxcompat -Wl,--no-seh
> >>> -Wl,--dynamicbase -Wl,--high-entropy-va -Wl,--image-base,0x140000000
> >>> -L/win64/vlc/contrib/x86_64-w64-mingw32/lib conftest.c >&5
> >>> /tmp/ccT0CMSB.o: In function `main':
> >>> /win64/vlc/win64/conftest.c:89: undefined reference to `inet_pton'
> >>> /win64/vlc/win64/conftest.c:89:(.text.startup+0xa): relocation
> >>> truncated to fit: R_X86_64_PC32 against undefined symbol `inet_pton'
> >>> collect2: error: ld returned 1 exit status
> >>> configure:25859: $? = 1
> >>> configure: failed program was:
> >>>
> >>> ...
> >>>
> >>> If needed, you can see the full config file below (1MB)
> >>>
> >>> https://www.dropbox.com/s/m2rklvzyl1lkst6/config.log?dl=0
> >>
> >> Yes, there are many different checks but in the end it is found.
> >> You can see HAVE_INET_PTON is set to 1 afterwards up to the end of the
> >> script. So it should be set to that value in config.h as well.
> >
> > Yes, it's set to 1.
> >
> > But libmicrodns wasn't built by my system because I'm using the prebuilt
> > contribs. So does that mean in the nightly build HAVE_INET_PTON was set
> > to 0?
>
> Possibly yes. It's not recommended to use prebuilt contribs in general
> in case you know you have the same toolchain as the build bot. I would
> assume it is the case with the docker but it seems wrong. So you should
> build the contribs locally. It will take longer but at least it's
> guaranteed to work.


Ok, thanks :-)

Roland


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