[Bug libstdc++/93602] Missing reference to libiconv in 9.x libstdc++

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93602

--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Liviu Ionescu from comment #0)
> GCC 7.x and 8.x are fine, with the same build procedure the libstdc++ shared
> library has no undefined references to libiconv.

Have you checked that recently? Could libiconv have been installed since your
last successful build?

> To be noted that on a newer system (a Manjaro) where 9.2 is installed,
> something similar happens:
> 
> $ readelf -s /usr/lib/libstdc++.so | grep iconv
>     24: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND
> iconv_open@GLIBC_2.17 (44)
>    125: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND
> iconv_close@GLIBC_2.17 (44)
>    174: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND iconv@GLIBC_2.17
> (44)
>   9033: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND
> iconv_open@@GLIBC_2.17
>  12636: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND
> iconv_close@@GLIBC_2.17
>  14045: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND iconv@@GLIBC_2.17
> 
> $ ldd /usr/lib/libstdc++.so
> 	linux-vdso.so.1 (0x0000007fbf4da000)
> 	libm.so.6 => /usr/lib/libm.so.6 (0x0000007fbf1d6000)
> 	libc.so.6 => /usr/lib/libc.so.6 (0x0000007fbf069000)
> 	/usr/lib/ld-linux-aarch64.so.1 (0x0000007fbf4ac000)
> 	libgcc_s.so.1 => /usr/lib/libgcc_s.so.1 (0x0000007fbf045000)

No, that's not similar at all. This is the expected behaviour, where the iconv
functions from glibc are used and so no additional library is needed. 

> It seems that in 9.x the build procedure expects the libiconv functionality
> to be provided by one of the other system libraries.

Again, I don't think anything changed in GCC 9.

You might be able to use one of these options to control which iconv lib gets
used:

  --with-libiconv-prefix[=DIR]  search for libiconv in DIR/include and DIR/lib
  --without-libiconv-prefix     don't search for libiconv in includedir and
libdir
  --with-libiconv-type=TYPE     type of library to search for
(auto/static/shared)