Linker error on Ubuntu 16.04 with conda-forge libraries (`-fno-plt`)

[pitrou]

On a Travis-CI Xenial VM, building Apache Arrow and linking it with some conda-forge libraries (here libprotobuf.a) produces a linker error at some point:

/usr/bin/ld: /home/travis/build/pitrou/arrow/cpp-toolchain/lib/libprotobuf.a(common.o): TLS transition from R_X86_64_TLSGD to R_X86_64_GOTTPOFF against `_ZSt15__once_callable' at 0x38e in section `.text' failed
/home/travis/build/pitrou/arrow/cpp-toolchain/lib/libprotobuf.a: error adding symbols: Bad value
collect2: error: ld returned 1 exit status

(full log at https://travis-ci.org/pitrou/arrow/jobs/480342375#L1220)

This is related to the conda-forge toolchain migration (previously things would work fine on the even older Trusty VMs).

The error may be due to a new GNU ld feature that is not recognized by Xenial's GNU ld version. According to one of the binutils maintainers, not using -fno-plt when building libraries would solve the issue:
https://sourceware.org/ml/binutils/2019-01/msg00115.html
https://sourceware.org/ml/binutils/2019-01/msg00131.html

[wesm]

Is this something that would have to be fixed in conda-forge's toolchain flags or somewhere else?

[pitrou]

AFAICT it's the ctng-compilers-feedstock recipe in this repository.

[jjhelmus]

-fno-plt is a security flag, this is not something that should be removed.

binutils and other toolchain related packages are created by the ctng-compilers-feedstock. The various compiler and linker flags are set in ctng-compilers-activation-feedstock.

[jjhelmus]

A similar issue was found when using system compilers to build python extensions, conda/conda#6030. The solution was to use the system compilers but link with newer version of ld that was included with the Python package. I suspect that a similar solution would be possible here, Apache Arrow can be compiled with system provided compilers but linking will need to be done with a compatible linker.

[pitrou]

It seems like using the conda-forge binutils package is working.