Re: _idn2_punycode_decode undefined for static linkage

[Tim Rühsen]

On 22.01.22 01:43, Todd Richmond wrote:
> Using latest libidn 2.3.2 compiled from source with gcc 11 on Linux, it 
> looks like the 2.3.0 version changes that modified the 
> _/idn2_punycode/_decode symbol for shared libraries causes static 
> linkage to fail. I can link against the .so correctly, but linking 
> against the .a causes the following error

You are absolutely sure that your application code doesn't use
_idn2_punycode_decode() directly ?

Because I can't reproduce this problem on Debian with
$ gcc --version
gcc (Debian 11.2.0-14) 11.2.0

and

./configure --enable-static --disable-shared
make clean
make

see `ldd src/idn2` - libidn2.a has been statically linked into it.

> ld: error: symbol _idn2_punycode_decode has undefined version IDN2_0.0.0

The library offers two symbols (nm -a libidn2.a)
0000000000000000 T _idn2_punycode_decode
0000000000000000 T _idn2_punycode_decode@IDN2_0.0.0

The code to generate this is in lib/puny_decode.c:

/* Create a compatibility symbol if supported.  Hidden references make
   the target symbol hidden, hence the alias.  */
#ifdef HAVE_SYMVER_ALIAS_SUPPORT
__typeof__ (_idn2_punycode_decode_internal) _idn2_punycode_decode
  __attribute__((visibility ("default"),
                 alias ("_idn2_punycode_decode_internal")));
__asm__ (".symver _idn2_punycode_decode, _idn2_punycode_decode@IDN2_0.0.0");


> Any possible workaround or compile change I need to make?

Possible solutions / work-arounds:

a) if you use _idn2_punycode_decode(): replace that with the appropriate 
idn2_to_ascii function.

b) In `config.h`, comment out the line that defines 
HAVE_SYMVER_ALIAS_SUPPORT and `make clean && make` to build the library 
again (check with nm -a that _idn2_punycode_decode@IDN2_0.0.0 is gone).


See also
https://gitlab.com/libidn/libidn2/-/merge_requests/82
https://gitlab.com/libidn/libidn2/-/issues/74


Regards, Tim

> Thx…

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