Hi,
My apologies if this is a general Arch issue, but it seems to be specific to ARM.
This is output I get from cmake, building a custom app which works fine everywhere else:
(internet searching seems to suggest this should be using -lpthread, not -lpthreads, or disabling this feature if it isn't supported in the built in c++ compiler)
Linking CXX executable cmTC_1b1c7
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_1b1c7.dir/link.txt --verbose=1
/usr/bin/c++ -DCHECK_FUNCTION_EXISTS=pthread_create CMakeFiles/cmTC_1b1c7.dir/CheckFunctionExists.cxx.o -o cmTC_1b1c7 -lpthreads
/usr/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
# uname -a
Linux alarmpi 4.9.50-1-ARCH #1 SMP Thu Sep 14 01:28:48 UTC 2017 armv6l GNU/Linux
Thanks!