-pedantic -Werror in cmakelist causes error when compiling on ubuntu18.04

[fjonasALICE]

I am building on Ubuntu 18.04.4 LTS with gcc Version 10.3.0. The following warning

2021-07-09@12:00:17:DEBUG:O2-full-system-test:DataDistribution:0: /software/flo/alice/sw/SOURCES/DataDistribution/heads-v1.0.0/0/src/common/base/DataDistLogger.h:377:11: warning: ignoring return value of 'int nice(int)' declared with attribute 'warn_unused_result' [-Wunused-result]
2021-07-09@12:00:17:DEBUG:O2-full-system-test:DataDistribution:0:   377 |       nice(+10);
2021-07-09@12:00:17:DEBUG:O2-full-system-test:DataDistribution:0:       |       ~~~~^~~~~

causes a crash on my system and I can only build succesfully when removing

if(NOT APPLE)
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pedantic -Werror")
endif()

from the cmakelist. Since I do not fully understand what was the original purpose using these specific compiler flags for none apple systems, I just open this issue and leave it up to the maintainers.

In addition the build failed on my system due to:

Undefined reference to 'dlsym'

which I could fix by adding

-Wl,--no-as-needed -ldl

to the cxx flags. However this might be an unrelated issue with my system, just wanted to leave this info here for future reference